A

MANUAL OF ANALYTICAL METHODS

FOR USE IN

THE CONTROL LABORATORIES

OF RAW SUGAR FACTORIES

Gardens Point A23205806B A manual of analytical methods for use in the control laboratories of raw sugar factories.

The Jamaican Association of Sugar Technologists 1987

Disclaimer: In some cases, the Million Book Project has been unable to trace the copyright owner. Items have been reproduced in good faith. We would be pleased to hear from the copyright owners. Queensland University of Technology. Brisbane, Australia

Lithographed in Jamaica by University School of Printing

PREFACE TO SECOND EDITION

The Committee of Comparative Factory Returns of the Jamaican Association of Sugar Technologists published the first edition of this Manual in an effort to standardise all analyses used for factory control purposes in the sugar factories, of Jamaica so that factory chemical reports might be rendered as comparable as possible. The large propor­tion of sugar cane now milled and bought on a recoverable pol % cane basis reinforces the necessity for the standardisation and accuracy of all sampling and analytical pro­cedures.

The Manual contains what the compilers consider to be the minimum of instructions and related information necessary to enable factory reports to be prepared in accordance with the form of presentation used in Jamaica. Only the actual operating instructions for performing the analyses are given; the theory of the respective analytical methods can be found in any of the standard published works on sugar analyses. The essential aim has been brevity, simplicity and accuracy, consistent with the practical requirements of factory control. First Aid precautions and a few miscellaneous analyses have been in­cluded for easy reference.

The Manual in its present form represents the combined efforts of the members of the Chemical Control Committee of the Jamaican Association of Sugar Technologists (Messrs. M.B. Floro, E.J. Mol, H.B. Springer, C.R.D. Shannon, P.D. Smith, K. White, J.R. Wotherspoon and H.M. Thompson) who wish to acknowledge their indebtedness to the other excellent Manuals of laboratory methods — Prinsen Geerlig's Chemical Control in Sugar Factories; Official Methods of the Hawaiian Sugar Technologists Association for Control of Sugar Cane Factories; System of Cane Sugar Factory Control of the Inter­national Society of Sugar Cane Technologists; Laboratory Manual for Queensland Sugar Mills; Recommended Methods of Chemical Control of the South African Sugar Techno­logists' Association; and the Cane Sugar Handbook by Spencer and Meade, which have acted as Works of reference in the preparation of this Manual. They are also indebted to Mr. R.E. Lawrence of Tate and Lyle Technical Services for his advice and criticisms and to Mr. J.G. Davies who was primarily responsible for the first Edition.

R.E. INNES on behalf of The Chemical Control Committee of The Jamaican Association of Sugar Technologists April, 1965

PREFACE TO THIRD EDITION

The Chemical Control Committee decided after careful study of the Second Edition (1965) that considerable change and up-dating were needed, due to ongoing development in the Industry.

The presentation and format have thus undergone extensive re-organization. Chapters on Boiler Water Treatment, Metrication and Apparatus have been added; New Methods of Analysis and the Special Analysis Chapter as well as Tables have been added.

As in the previous edition, the aim of this manual is brevity, simplicity and accuracy; only actual operating instructions for performing the analyses are given, theory is to be found elsewhere.

The preparation of this manual has been the work of L.O.O. Brown, W.O. Bailey, D.Y. Byfield and M.McA. D. Dilworth, assisted by Dr. H.C. Bourzutschky, L.R. Johnson, W.O. Ricketts and J. Jaddoo.

References used in the preparation of this manual include Prinsen Geerly's Chemical Control in Sugar Factories; Official Methods of the Hawaiian Sugar Technologists As­sociation for Control of Cane Factories; System of Cane Sugar Factory Control of Inter­national Society of Sugar Cane Technologists; Laboratory Manual for Queensland Sugar Mills; Recommended Methods of Chemical Control of the South African Sugar Techno­logists Association; Manufacture and Refinery of Raw Cane Sugar by Baikow; Cane Sugar Handbook by Meade and Chen.

M.McA.D. DILWORTH on behalf of The Chemical Control Committee of The Jamaican Association of Sugar Technologists April, 1987

TABLE OF CONTENTS

Chapter I Definitions 1

Chapter II Determination of Quantities 6

Chapter III Apparatus 8

Chapter IV Sampling 28

Chapter V Methods of Analyses .. 37

Chapter VI Special Analyses .. 71

Chapter VII Boiler Water Treatment .. 85

Chapter VIII Standard Solutions and Reagents 97

Chapter IX Calculations and Formulae 106

Chapter X Time Accounting 116

Chapter XI Metrication 120

Chapter XII Lab Management and First Aid 125

APPENDIX/ TABLE INDEX 133

Appendices 134

Tables 139

CHAPTER I

DEFINITIONS

Ash

Inorganic residue remaining after incineration. In practice, the proportion of residue remaining as 'ash' is influenced by the conditions of combustion, so that ash, as actually determined is not an absolute quantity. This term will refer to 'sulphated' ash unless otherwise specified.

Bagacillo

Fine particles separated from bagasse for filter aid (or strained from mixed juice (cush-cush)).

Bagasse

The residue left immediately after expressing the juice from the cane.

°Brix

The concentration (in grams solute per 100 grams solution) of a solution of pure sucrose having the same density at the same temperature as the solution being tested. If the Brix is detennined by refractometer, it should be termed Refractometer Brix. The weight of Brix is synonymous with Gravity Solids.

Cane

The raw material delivered to the mill, from which sugar is recovered, including clean cane, trash and other extraneous matter. In factories at which a cane cleaning plant operates, this should be specified as Gross Cane, which, after cleaning becomes Net Cane.

Cush-Cush

A mixture of water, juice and bagacillo collected as droppings during milling and straining.

Condensate

Water which has been condensed from steam or vapour liberated from boiling juices.

Crystal Content

The quantity of crystalline sugar present in Massecuites, or magma expressed as a percentage of brix or total weight.

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I.

Dilution Indicator

The fraction moisture to dry non-pol (sucrose) expressed as a percentage, i.e.

This factor is used to predict the keeping quality of new sugar. Below 40% - keeping quality is good. Above 50% - keeping quality is poor as the probability of deterioration is high. Between 40-50% - keeping quality is doubtful.

Dilution Water

The portion of the imbibition or maceration water in the mixed juice.

Extraction

(a) (Pol). Pol or Sucrose extracted in the milling plant per 100 Pol or Sucrose in the milled cane. The term extraction will refer to Pol extraction unless otherwise specified.

(b) (Reduced Pol). An expression of Pol Extraction in terms of a standard fibre of 12.5% on cane (mainly for comparative purposes).

Extraneous Matter

That portion of the material received as cane, which by arbitrary standards, is considered not to form part of clean cane. It consists of loose and adhering trash, tops, roots, dirt, suckers etc.

Fibre

The dry, water insoluble matter in cane.

Filter Cake (mud)

The residue removed from process by filtration.

Imbibition

The process in which water or juice is put on bagasse to mix with and dilute the juice present in the bagasse. The water so used is termed "Imbibition Water".

Java Ratio

The ratio of the percentage of Pol in milled cane to Pol in first Expressed Juice, i.e.

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Juices

(a) Absolute: All the solids in solution together with all the water in cane. Absolute Juice = (Cane — Fibre).

(b) Clarified: The juice obtained as a result of the clarification process. It is synonymous with Evaporator Supply Juice when the Filtered Juice is return­ed to Mixed Juice tank.

(c) Filtered: The combined filtrates from the filters.

(d) First Expressed: Synonymous with Crusher Juice. The juice expressed from cane by the first two rollers of the milling tandem.

(e) Last Expressed: The juice expressed by the last two rollers of the milling tandem.

(f) Residual: The juice left in the bagasse after milling, i.e. (Bagasse - Fibre).

(g) Mixed: The juice sent from the milling plant for further processing.

Losses

(a) Boiling House: Difference between Pol in mixed juice and Pol Recovered, i.e. (Pol in filter cake + Pol in final molasses + Pol in undetermined).

(b) Total: Difference between Pol in cane and Pol Recovered, i.e. (Pol in bagasse + B.H. losses).

Massecuite The mixture of crystals and mother liquor discharged from the vacuum pan.

Massecuites are classified according to stages of boiling (or descending purity) as A, B and C. Magma

A mixture of crystals and sugar liquor produced by mechanical means.

Milling Loss

The Pol to Fibre ratio of bagasse expressed as a percentage.

Moisture

Loss in weight due to drying under specified conditions expressed as a percentage of the total weight of the product being examined.

Molasses

The mother liquor separated from a massecuite. It is distinguished by the same terms as the massecuite from which it was separated, i.e. A, B or C.

Molasses — Final

The molasses from low grade boilings from which no further sugar is to be removed.

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Normal Weight

The weight of sample equal to that weight of pure cane sugar which, dissolved in water to a total volume of 100 millilitres at 20°C, gives a solution which, when read on a saccharimeter in a tube 200 mm long at 20°C, shows a reading of 100 degrees of the scale.

For saccharimeters equipped with the Ventzke scale, calibrated according to the Herzfeld-Schonrock value of the 100 point, this weight equals 26.026 g. weighed in air with brass weights, and for those with the International Scale 26.000 g. weighed in air with brass weights.

Non-Sugars (Pol)

The difference between Brix and Pol.

Pol (Apparent Sucrose)

The value determined by direct or single polarization of the normal weight solu­tion in a saccharimeter. The term is used in calculations as if it were a real substance.

Purity

(a) Apparent = Pol x 100

Brix

(b) Gravity = Sucrose x 100

Brix

(c) True = Sucrose x 100

Dry Substance The apparent and gravity purities of a sugar are the fractions (a) and (b) above, in which (100 - % Moisture) is substituted for Brix.

Remelt

A solution of low grade sugar in either clarified juice or water.

Safety Factor

A ratio indicating the probable keeping quality of raw sugar:

= % Moisture in Sugar

100 - % Sucrose (or Pol) in the Sugar

A factor exceeding 0.25 is considered dangerous.

Seed

Small grain sugar crystals used as nuclei (footing) in the crystalization process.

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Sucrose

The pure chemical compound commonly known as cane sugar. As used in these methods the term sucrose shall mean the result obtained analytically by the Lane & Eynon Method.

Sugar

(a) Commercial: (i.e. Raw Sugar) Sugar in the condition in which it exists at the completion of the factory process.

(b) Invert: The equimolecular mixture of glucose (dextrose) and fructose (laevulose) which results from the hydrolysis or inversion of sucrose.

(c) 96°: A value used for reporting chemical sugar on a common or uniform basis; calculated from an empirical formula (usually the S.J.M. formula using the purity of the final molasses produced by the factory).

(d) Reducing: (Reducing Substances). The reducing substances in cane and its products calculated as invert sugar.

(e) Total: The combined percentages of sucrose and reducing sugars in a sample.

Suspended Solids

The solids in juice or other liquid recoverable by decantation or mechanical means (this refers to mixed juice unless otherwise specified).

Syrup

The concentrated clarified cane juice before crystallization, i.e. the solution leaving evaporators.

Vapour

Steam obtained from boiling sugar liquor.

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CHAPTER II

DETERMINATION OF QUANTITIES

Methods of Weighing and Measuring

Cane

The weight as recorded at the weigh-bridge, i.e. weight of transporting vehicle with canes, less tare weight of vehicle, less weight of any chains, slings etc.

(All weights and weighing machines should be kept clean and checked at frequent intervals with official standard weights at the range of weights being recorded. The scales should be zero tested several times a day and at start of each shift. The aprons at either end of the scales should be level).

The weights so arrived at will be GROSS CANE, the weight of NET CANE shall be arrived at by correcting the weight Gross Cane for the weight of trash and any other extraneous matter.

NOTE

I. The accuracy of the Net Cane, i.e. the weight of cane, is no better than the accuracy of the TARE of the TRANSPORT VEHICLES. STRICT attention should therefore be paid to this.

II. Cane normally loses weight during storage due to evaporation. In addition there may be a significant gain in weight if rain falls on the stored canes, i.e. the effect in both cases is to cause an unknown difference in weight between cane as weighed and cane as milled and analysed. The problem is of course compounded by Factories with washing plants.

Imbibition Water

By weight or by an approved form of metering

Mixed Juice

By weight or by mass flowmeter. It is normal to put all additives, i.e. filtrates, lime etc., after the weight has been determined. If any of these must be added before the weighing, the weight of added material must be determined and allowed for.

Net Mixed Juice

This is arrived at by analysing the mixed juice above for % suspended solids and making deductions from Mixed Juice above, i.e. Net Mixed Juice = (100- % suspended solids) X Tons Mixed Juice.

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Bagasse

By calculation. i.e. Weight bagasse = Weight Cane + Weight Imbibition Water - Weight of Mixed Juice

NOTE

Successful methods of weighing bagasse have been developed, and where installed these should be used. One of the most convenient devices is the continuous belt type of weigher, using beam balance or load cell detection of the weight. Because of the relatively low weight of bagasse to that of the conveyor belt great attention must be paid to the tare weight.

Final Molasses

By weighing using a scale, water column or air pressure, preferably the first.

Filter Cake

By weighing in trucks as discharged. Where this cannot be done, by taking frequently the weight of a representative sample of known areas from the filter.

Sugar

By weighing using continuous belt type of weigher or other automatic scales. Where this is not possible all bulk sugar trucks must be weighed and the Net Weight of sugar obtained. Where bagging is still practised, the counterpoise should be set at a point corresponding to the standard sugar weight plus the average weight of the bag obtained by weighing 50 or 100 at a time, once per day. Alternatively, every 10th bag should be check-weighed.

(All sugar scales should be checked regularly with standard weights at the range of weights being recorded).

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CHAPTER III

APPARATUS

The apparatus described in this chapter are to be found in the routine sugar laboratory and are by no means exhaustive. It gives a guide as to the requirements of the control laboratory. Manufacturers' Trade names are used only for purposes of illustra­tion.

Standardisation

Bagasse Disintegrators: These shall be built to the specifications laid down in the Queens­land Sugar Manual, except that the blades shall rotate at 2800 rpm.

Brix Hydrometers : Hydrometers shall be standardised at 27.5°C.

Hydrometer Jars : Jars or cylinders must allow not less than ½ inch clearance between their walls and the bulb of the hydrometer.

Pipettes : To discharge pipettes use the following procedure, specified by the U.S. Bureau of Standards.

"After filling remove the excess liquid adhering to the tip. In emptying hold in a vertical position, with the outflow un­restricted until the surface of the liquid reaches the upper end of the tube below the bulb; then touch the tip to the side of the receiving vessel; keep in contact until the liquid has ceased to run freely and immediately withdraw."

Refractometers : The scale should be tested by the use of freshly distilled water free from air. When testing with water it is essential to correct readings to the standard temperature.

Saccharimeters : All saccharimeters should be standardised at 20°C, and should use the International Sugar Scale (S) which is defined: 100°S is the polarization of the normal solution — 26.00 g of pure sucrose weighed in air with brass weights, dissolved in distilled water and made up to 100 ml at 20°C and used in a tube of 200 mm length at 20°C upon a saccharimeter calibrated at 20°C. Each laboratory should be equipped with two quartz control plates calibrated as follows: One between 94°S and 96°S and In standardising saccharimeters, the quartz control plates must be allowed to come to the temperature of the polariscope room

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Volumetric Glassware: All volumetric glassware shall be calibrated at 27.5°C.

Bagasse Disintegrator: Use Pol determination in bagasse.

Fig. 3.1 - Wet Disintegrator

and the reading must be corrected to 20°C by the use of the tables provided in this manual. (See Appendix).

Sugar Flasks : (for control laboratory purpose) Standard flasks shall be of Grade A, BS615 and BS675 and shall be calibrated at 27.5°C.

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Equipment : The machine should be that of Australian design. (See fig. 3.1). It should be built to the following specifications: Blades - should be 6" in length, rotated at 6,000 rpm and must be sharp. The bottom blade must not be more than ¾" from the bottom of the container. (See fig. 3.2).

Fig. 3.2. • Blade Section of the Wet Disintegrator

Preparation must be made for the can to be water cooled if excessive heating occurs during the disintegration. An alternative disintegrator is the Waring Commercial Blender Model CB4, but this machine is of lower capacity. Since the mixing capacity of the Waring device is 1 gallon (3785 ml), a sample as large as 300 gm can be used with the 10:1 ratio required. Disintegration time of 20 minutes is sufficient. Parallel tests with the other method will readily establish the time required for complete disintegration.

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Cleaning : The blades and the container should be thoroughly cleaned after use.

Balances

1. Analytical balances, preferably modern rapid-weighing digital-reading type, for ash, moisture, reducing sugar determination and for general analytical work.

(a) Single Pan type - Mettler analytical balances or equivalent capacity 200 g.

(b) Double Pan type - Analytical, Rider type; capacity 200 g.

2. Heavy duty balances for dilutions, bagasse moisture and multi-purpose weighing. (See fig. 3.3.). Double Pan sliding weight type - Capacity 2 kgm.

Fig. 3.3. Double Pan Sliding Weight Balance

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Care and Use

The analytical balance is designed for high precision measurements and its various essential parts are delicately constructed. Hence, extreme care must be used in its opera­tion and maintenance.

Assembly

Detailed instructions for assembly are supplied with each balance and should be rigidly followed in setting up a new balance.

Location

The balance should be mounted on an antivibration bench. It should be free of dust, moisture, draught and extensive changes in temperature.

Cleaning

The balance should be cleaned periodically. A soft hair brush is recommended for removing dust from the pans and other surfaces. Extreme care must be used to prevent damage when cleaning the knife edges. The balance should be covered when not in use.

Operation

Single Pan Balances

The balance should be arrested before loading or unloading if a pan arrest is provided. The balance should be levelled and the pointer reading zero (or the desired tare). All readings on closed case balances should be made with the case closed. Readings on open balances should be made under conditions in which the pan is protected from draughts. The balance should be arrested and the scale light off when the balance is not in use. A suitable type is shown in fig. 3.4.

Fig. 3.4. - Mettler Single Pan Analytical Balance

Double Pan Balances

The balance should be arrested when loading or unloading the pans and when not in use. Before making a series of weighings, the balance should be levelled and adjusted so that the pointer swings an equal distance on either side of the zero point when the beam is set in motion with no load on the pan. Fig. 3.5 shows such a balance.

12

Final adjustments with the rider, chain-matic vernier and observations of the pointer swing should be made with the balance case closed. Always close the case when leaving the balance. The balance should never be overloaded.

Fig. 3.5. - Double Pan Analytical Balance

Balance Weights

Double Pan Balances — A separate set of weights should be provided for each balance and should be kept in a clean place. Weights should never be touched with the fingers. Forceps should be used to handle analytical weights.

Baths, Water

Rectangular shape made of copper or stainless steel and electrically heated.

Beakers

1. Glass — Pyrex brand. With or without spout. With or without graduation of capacity ranging from 200—1000 ml.

2. Metal - Made of copper or stainless steel for dilution of massecuites and molasses. The 1000 ml size is recommended.

3. Plastic — Made of polyethylene.

Bottles

1. Reagent

(a) Narrow mouth, amber or clear glass with plastic screw cap. These are used for most reagents and solutions.

(b) Plastic polyethylene with polyethylene screw caps. These are suitable for all solutions and reagents.

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2. Dropping

(a) Flint glass with mushroom shaped grooved stopper having projected lug, to deliver contents drop by drop.

(b) Pyrex glass with standard taper ground glass, pipette, graduated to deliver 0.5 ml or ungraduated for general use. The pipette assemblies are inter­changeable among similar bottles.

3. Washing

Plastic polyethylene. A squeeze delivering a drop or steam.

Buckets

Made of polyethylene plastic. Equipped with carrying handle and pouring spout.

Burettes

1. Pyrex glass with Teflon instead of glass stop cock. Teflon requires no lubricant and provides precision control of flow, 50 ml capacity.

2. Automatic - Pyrex glass, available in many varieties and capacities and are con­venient for many routine control titrations.

Use

The burette should be in vertical position in the burette stand and should not be held with the hand. After the outflow ceases, touch the side of the receiving vessel to the tip to remove suspended drop. The reading should be made at the lowest part of the meniscus, with the high level with the surface, except when reading dark coloured liquids when the reading is made on the surface.

Crystal Volume (Apparent)

The device used for this determination hydraulically presses from the massecuite the volume of mother liquor in excess of that required to fill the pores of the apparent volume of the crystals. The apparent crystal volume is read from the scale. See fig. 3.6.

It allows the apparent crystal volume in a massecuite to be determined quickly and easily at any stage of the low grade processing from pan to centrifugal.

Cylinders

Graduate. Made of heavy glass, pyrex or polyethylene plastic. 50, 100, 500 and 1000 ml sizes.

Desiccators

Pyrex glass, with taper-stopper sleeve. Inside diameter 200 mm with perforated plate.

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Use

Desiccants (drying agents) should always be changed when they have lost their drying power. A desiccator should never be left open any longer than is necessary to load or unload. A lubricant such as Vaseline should be used on the ground glass joints.

Fig. 3.6. - Apparent Crystal Volume Apparatus

Dishes

1. Evaporating

Translucent fused silica can be used in many applications including ash determina­tion as an inexpensive and completely satisfactory substitute for platinum dishes. For long service life, the practical maximum temperature of prolonged heading is about 1000°C (1832°F). Capacity: 100-125 ml.

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2. Moisture

(a) Bagasse moisture — Shallow metal tray about 13 x 23 x 5 cm deep made of thin copper or aluminium.

(b) Filter cake moisture — Aluminium moisture dishes with cover 90 mm in diameter by 50 mm deep.

(c) Sugar moisture - Aluminium moisture dishes with cover 50 mm diameter by 22 mm deep.

Filter Paper

Whatman No. 1 or equivalent, 18.5 cm diameter. This is a medium weight paper (white) and rapid filtering.

Flasks

1. (a) Bates Sugar — Volumetric, of Pyrex glass, for sugar Pol determination.

(b) Kohlraush — Volumetric, of Pyrex glass, for molasses, sugar and filter cake. (Fig. 3.7). Pol determination 50-55 ml, 100-110 ml.

2. Erlenmeyer - Pyrex glass, narrow mouth with graduation. For general, Pol and reducing sugars determination 250, 300 and 1000 ml sizes. (Fig. 3.8).

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3. Filtering — Pyrex glass, heavy wall with side tubulation. Neck is finished to provide fit for a buckner funnel. (See fig. 3.9.).

4. Volumetric - Pyrex glass with glass stopper, for determining sucrose, reducing sugars and for the preparation of reagents. 100 ml, 200 ml, 500-2000 ml. (fig. 3.10).

Funnels

1. Glass - Short stem, long stem and stemless. O.D. 11 cm. Use 18.5 diam. filter paper.

2. Plastic — Made of polyethylene. Short stem, long stem and stemless.

3. Porcelain - (a) Buchner, for vacuum filtration with fixed perforated plate, glazed inside and outside.

(b) Buchner, table type, with side outlet for vacuum filtration. May be used with or without a filtering flask.

Furnace

For ash determination. Chamber dimensions inside: Width 10.2 cm, height 9.5 cm, depth 22.9 cm. Operating temperature up to 1000ºC, equipped with built in temperature controller and indicating pyrometer.

Gas Analysis Apparatus

Use - To determine the constituents of flue-gas.

Equipment

A convenient apparatus for this analysis is that of Orsat. Fig. 3.11 illustrates a form of this apparatus having a four-way stopcock. The apparatus consists of a water-jacketed burette, for the measurement of the gases and three absorption U-tubes with suitable connections and stopcocks. The absorption branches of the U-tubes are filled with pieces of small-bore glass tubing to increase the surface exposed to the gas.

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The absorption tubes are connected with the burette by barometer tubing of very small bore. The branches of the U-tubes at the rear are usually connected with a soft rubber bulb (not shown in the fig.) to prevent exposing the solutions to the air and thus weakening them. The water jacket on the burette is for maintaining a fairly constant temperature during the test.

Glass Beads

Solid glass, approximately 3 mm in diameter, used in reducing substances determina­tion to prevent spattering of boiling solution.

Hot Plates

Used for evaporation, boiling and general laboratory work. Thermostat control would be an advantage.

Hydrometers

Range 40 to 50 brix in 0.1° subdivisions. Calibrated at 27.5°C, for determination of the brix of final molasses.

Jars

For storage of juice, syrup, molasses and sugar samples. Should be made of glass, wide mouth of approximately 3 litre capacity.

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Massecuite Filter This allows a sample of mother liquor to be extracted from a massecuite (cyclone

sample). This can be effected by a laboratory basket type centrifugal and a pressure filter.

Laboratory basket type centrifugal

This is not recommended as it is not able to efficiently handle low grade massecuites and has the added disadvantage that a significant proportion of water is evaporated from the molasses in the process, this however does not influence the purity of the molasses but does alter the sucrose and total solids concentrations.

Pressure Filter

This consists of a water-jacketed pressure vessel with removable top and bottom covers. The bottom plate is provided with drainage channels leading to a central hole, and supports a screen 9100 and 8 mesh) on which the actual filtration is achieved. See fig. 3.12.

Fig. 3.12. - Massecuite Filter

The massecuite is placed in the sealed vessel and air pressure applied at the top; the massecuite is forced out through the screen. A moisture trap may be used in the air supply line to prevent dilution of the massecuite.

Massecuite Mixer

Use - In preparing massecuites and molasses samples for analysis. Fig. 3.13 shows a typical stirrer.

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Fig. 3.13. — Massecuite Mixer

Microscope

In sugar factory operations the most important use of the microscope is for the examination of proof samples withdrawn from the vacuum pans and for the determina­tion of the uniformity and sizes of crystals in sugar, massecuite, magma, granulation (seed) etc.

The microscope required for the above is essentially of low magnification. However, a fairly high degree of magnification is required for other casual uses and a versatile instrument of good quality is required for laboratory use.

Description

Microscopes are generally classified as simple or compound type.

(a) Simple microscope - This includes hand lens and tripod magnifier which is used by sugar boilers, it produces an image in the observers eye, exactly like the original object but larger. The magnification is usually not greater than ten diameters.

(b) Compound Microscope - The compound microscope differs from the simple ones in that they have lenses called objectives producing an image of the object which is observed through another lens called the ocular (eye piece). The monocular type fulfils most of the needs of the sugar factory laboratory. The distinct parts are: the base, the arm, the body which carries the optical system and the stage upon which the sample under examination rests. A suitable type is shown in Fig. 3.14.

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Care

The eyepieces and objectives must be kept clean by removing dust particles with a soft hair brush. Dirty lenses can be cleaned with lens tissue moistened with water or alcohol.

Fig. 3.14 - Compound Microscope

Moisture Teller

Dietert, thermostatically controlled hot-air dryer for determination of bagasse mois­ture. The sample is weighed into the sample pan and dried for a predetermined time at a specific temperature.

Ovens

Double walled type with blower fan. Suitable for moisture determination and other miscellaneous uses in the laboratory. Oven chamber size — 50 cm wide x 50 cm long x 50 high.

pH Meters

0 - 14 pH direct reading type with temperature compensation. Fig. 3.15 shows a suitable type.

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PH Meter

Use and Care Instrument must be kept clean and dry at all times. The glass electrode should be kept

immersed in distilled water when not in use. It is not advisable to leave calomel electrodes soaking in water for extended periods of time due to the danger of diluting the KCL solution inside the electrode. The electrode may be left immersed in saturated KC1 solutions for long periods or stored dry by replacing the rubber cap on the bottom and the stopper in the side hold to prevent loss of KC1 solution.

Fig. 3.15 - pH Meter

Glass electrodes should be cleaned by immersing in approximately 0.1 N HC1. New electrodes should be allowed to stand for 12 hours in the acid before use.

Electrodes should not be allowed to rub against sides or rest on the bottom of beakers as they are easily broken.

The calomel electrode should be refilled with saturated KC1 as is needed to keep it nearly full and KC1 crystals added if necessary to maintain saturation.

Pipettes

Measuring pipettes with graduated scale and straight tube above taper. Capacities: l - 5 0 ml in l/10 ml subdivisions.

Use — To maintain accurate measurements, the following procedure should be followed:

1. After filling, remove excess liquid from the tip and dry outside the delivery tube before adjusting the volume to the mark.

2. To empty, hold the tube in the vertical position, with the outlet unrestricted, until the surface of the liquid reaches the upper end of the delivery tube. Then touch the tip to the side of the receiving vessel and keep in contact with it until the emptying is complete.

3. Never blow out the liquid remaining in the tip.

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Refractometer

The refractometer is quite satisfactory for determining the total solids present in a solution and has the advantage of speed, ease of manipulation and the small amount of sample required.

The instrument commonly used is the Abbe refractometer, shown in Fig. 3.16.

Fig. 3.16 - Abbe Refractometer

For measuring the brix, the illuminating prism is swung open, a drop of the liquid to be tested is applied to the horizontal surface of the measuring prism, and the prism is swung back.

The border line, as a separating edge between the dark and light field, is superimposed on the scale image in the field of view gives the brix of the sample. In some instruments a pinion knot sets the border line and have a second scale above the brix scale which gives the refractive index. A sodium vapour lamp which gives monochromatic light is used as the source of illumination. The measuring prism used is made of hard crown glass.

The Hand Refractometer, of which one type is illustrated in Fig. 3.17. is useful for the approximate checking of brix, particularly in maturity testing in the fields.

Fig. 3.17 - Hand Refractometer

Care

Every effort should be made to prolong the life of this expensive piece of equipment.

1. The instrument should be kept clean and dry as possible at all times.

2. Put a drop of light oil each day on the prism hinge.

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3. The sodium vapour lamp light should be kept continuously when the instrument is being used frequently.

4. After each determination the prisms should be cleaned with wet filter paper and wiped dry with a piece of soft cloth.

Operation

1. Circulate the cooling water and turn on the sodium vapour lamp, which requires approximately 5 minutes to come to full glow.

2. Check the zero point with distilled water and adjust if necessary.

3. Rinse the prism two or three times with the solution to be analysed by alternately filling the space between them and opening and closing the prims box. Fill the space between the prism with the solution and allow approximately a half minute for it to come to prism temperature.

4. Record the scale reading and temperature. Three readings of the scale should be taken and the average of these recorded as the scale reading.

5. Dark areas in the field could be due to the solution being turbid. The sharpness of the dividing line can often be improved by varying the position of the sodium vapour lamp.

Saccharimeter (Polariscope)

A saccharimeter is a polarimeter designed specifically for use with sucrose solutions. The whole area of study of polarimetry and saccharimetry is that branch which refers specifically to sucrose solution. Hence, the saccharimeter is a polarimetric instru­ment which enables the sugar analyst to determine quantitatively and rapidly the amount of sugar in the solution. It is however normally referred to by laboratory personnel simply as polariscope and it is this term that will be used as synonymous with saccharimeter.

The polariscope operates off the principle of polarized light. Ordinary light vibrates in all directions, but light which vibrates in only one plane is called polarized light.

Many substances, including solutions of sucrose and other sugars have the power to rotate polarized lights. The angle or amount by which the plane of polarized light is rotated is measured by the polariscope and it is by this means the quantity of sucrose present in the solution is determined. In other words the analysis of sucrose by the polar­iscope employs the measurement of the degree of rotation of plane polarized light.

Since sucrose rotates the plane of polarized light to the right it is termed a right-hand or dextrorotary sugar. Fructose rotates the plane of polarized light to the left and is a left-hand or levorotatory sugar. In the construction of the polariscope the polarisation of the ordinary light (white light) is accomplished by passing it through a Nicol prism, made from iceland spar crystal. The section of the instrument is called the polarizer.

After leaving the polarizer, the plane polarized light is rotated by the sugar solution contained in a tube (polariscope tube). The light then enters the analyser which is another Nicol prism equipped with a scale which allows the degree of rotation to be

24

measured and hence the quantity of sucrose in the solution. (Fig. 3.18).

Fig. 3.18 - Schmidt and Haensch Polariscope

Care

1. The instrument must be kept clean and in a well ventilated room which is free of vibration.

2. It should not be kept in a hot place nor leave illuminating light on when not in use. The deterioration of the prism cement is accelerated by high temperatures.

Calibration

The instrument should be checked and adjusted if necessary at the commencement of each shift with quartz plates which are calibrated as follows: one between 94°S and 96°S and the other between 50°S and 60°S.

Operation

1. Check the zero point and adjust if necessary.

2. Determine the zero point correction with the observation tubes filled with distilled water. The end cover glasses can be adjusted, eliminate the optical nature of the tube.

3. The observation tube should be rinsed at least three times with the solution to be read, placed in the trough midway between the two ends and read.

4. The temperature of the solution should be approximately that of the instrument.

5. The reading should be taken after setting the instrument for equal intensity of both halves of the field.

6. At least three readings of the same sample should be taken and the average result recorded as Pol reading.

25

The microscope for reading the scale and the telescope for the observation of the field of view are focused by turning the knobs of the eye-piece. When observing the two photometric fields, the slightest turning of the knob will cause a change in the luminous intensity of the photometric fields. It is now the point to find that position in which there is no difference in the luminous intensity of the two fields i.e. the two halves of the images are matched. See diagram below. The scale reading is taken at this point.

Two halves of the field (image) to be matched

Fields are matched

Reading the Scale

The 100 degree point of the international saccharimeter scale is determined by polarizing a solution containing 26 gm of sucrose (weighed in air with brass weights) in 100 ml at 20°C in a 200 mm tube. The scale shown in Fig. 3.19 is marked by the following: R - side of reading for dextro-rotatory solutions

L - side of reading for levo-rotatory solutions

The point at which the value is read is marked by the line extending across the scale. If the large figures appear on the side marked R, the small figures of the right-hand side relate to the further readings. If the large figures appear on the side marked L, the small figures of the left-hand side relate to the further readings. See Fig. 3.19 below.

Fig. 3.19 - The scale employed in the Schmidt and Haensch instrument. Reading 66.3°S

26

The line extending across the scale in the diagram above bears the figure 60 on the side marked R.

Reading: Dextro-rotatory solution +60°S The continuous line has passed figure 6 on the scale. Reading: +6°S The continuous line coincides with the third (3rd) division over a full degree. Reading +0.3°S

Value = +66.3°S

Automatic Saccharomats have been available for some time but their high-eost prohibited their use in sugar factory laboratories. A low cost instrument is now available from Optical Activity (fig. 3.19A).

Fig. 3.19A - Automatic Saccharomat

SUGAR DISSOLVER USE - for dissolving sugar

Fig. 3.20 sugar dissolver

27

CHAPTER IV

SAMPLING

Representative sampling is of the utmost importance. If a sample does not truly represent the average composition of the material, the most carefully conducted analysis will be of no value. In fact it could be misleading to the operating personnel.

Where the operation is continuous it is best to collect a continuous sample, always in proportion to the quantity of the material being sampled. Automatic sampling devices which fulfill these conditions should be used wherever practical. If continuous sampling is impossible, proportional samples should be taken at regular, frequent intervals.

All sampling devices must be kept clean and in perfect working order to prevent contamination of the sample or irregularities in sampling. Automatic sampling devices should be designed so that:

1. The sample taken is representative and proportional to the total quantity of material.

2. They are as self-cleaning as possible and can be easily cleaned.

3. They will not be subject to mechanical failure.

4. Evaporation or moisture absorption will not occur.

Manual intermittent sampling and composition are to be preferred to a continuous or automatic device which is subject to contamination or mechanical failure.

In the case of all weighed products, the sample should be taken at the point where the product is weighed and in the same condition.

Sample Devices and Containers

To ensure that the sampler itself does not become a source of infection, causing decomposition of the samples it must be kept thoroughly clean, with frequent steriliza­tion. Cleaning by means of steam jets is usually the most convenient and efficient method. This should be done several times per day.

Ideally, sample containers should be seamless, stainless steel, copper, enamel or plastic. Containers for different types of juices should be readily distinguishable.

Preservatives

A preservative must be added to the samples in compositing.

Brix and Ash Determination

Samples to be used for Brix and Ash determination may be preserved with mercuric chloride. 0.5ml of a saturated alcohol solution of the salt per litre of juice should be added. An alternative which is not as effective as mercuric chloride is formalin (40% for­maldehyde) 0.3 to 0.5ml per litre should be added to the sample.

Both formalin and mercuric chloride should not be used in samples taken for reducing sugar analysis because they are copper reducing.

28

Precaution

Mercuric chloride is poisonous. It should not get on the hands or mouth and excess of samples treatment with mercuric chloride should not be returned to process.

Pol determination

Samples for Pol determination are most effectively preserved by means of lead sub-acetate (Home's dry lead). 20 g per litre of juice is the amount which should be used. Lead subacetate has a small but sometimes Negligible effect on the refractometer solids reading.

Addition of Preservative

The amount of preservative added to the sample should be in proportion to the amount of sample to be composited. For example, if 100 ml is to be composited, 2 g of the dry lead salt should be shaken. A similar procedure should be used for mercuric chloride.

All the preservative required for the complete sample should never be added before compositing has started.

Freezing

Freezing may be used to preserve samples for an extended period of time, but mercuric chloride should be added to prevent deterioration.

Bagasse collecting All samples should be taken across the full width of the discharge chute and to the

full depth of the blanket. Bagasse loses water easily, especially with hot imbibition, and also deteriorates very rapidly due to the action of the enzymes and micro-organisms. Agitation causes mechanical segregation of the different particles. Provided moisture changes are recognised, a quick acting shutter in the bagasse elevator through which the whole of the bagasse conveyed by one lath is dropped through a closed chute into a cylindrical container can be used. The contents of the container can be mixed by a suitable manually or mechanically operating mixing gear.

If hand sampling is resorted to, this must be done systematically, at short distances across the entire blanket and down to the bottom of it, without any tendency towards selection, and, most important of all, at regular frequent intervals.

A convenient hand sampling method is to fashion two pieces of light 3 in. x 4 in. board into a 'V' shaped trough, which should be as long as the last mill is wide. Two people are necessary to operate this sampler effectively. Samples are taken by holding the trough in the bagasse discharge from the last mill and withdrawing it after it is filled (which is almost instantly) by an upward motion so that the trough is equally full along its whole length.

29

Preparation (Compositing/Analysis)

The sample container must be completely emptied out on to a clean dry surface. The sample is thoroughly mixed by hand, making sure that the hands are clean and dry and that the operation is conducted without loss or gain of moisture on the part of the sample. It is then heaped into a cone-shaped pile and divided vertically into quarters. Two opposite quarters are discarded and the process repeated until a suitable size of sub-sample is obtained.

The sub-sample is then tightly packed into a 16 oz. capacity dry clean sample container with a tight cover. It is then transferred to a closed container containing preservative. A suitable type container is shown in Figure 4.1.

Fig. 4.1. Bagasse sample container

When possible the timing of the sampling should be such as to permit the sample of bagasse to relate to the sample of the Last Expressed Juice.

The containers must be thoroughly cleaned and disinfected after each use. The time interval between sampling and analysis should not exceed three hours.

Preservative

Four (4) drops formalin or four (4) drops 10/l (vol/vol) ammonia (Sp. Gr. 0.380) and chloroform mixture in each 16 oz bottle full of prepared sample.

30

Frequency

Samples should be taken not less frequently than once every 30 minutes.

FILTER CAKE

Sample Collecting

Samples should be taken across the entire width of the rotary filter or if the mud is discharged into a container for removal, such as a trolley, a sample withdrawn by a tabular "trier" long enough to penetrate the full depth of the container, may be used. The triers should be withdrawn at least three times to each load and the samples stored in clean, glass screw-capped bottles.

Preparation (Compositing/Analysis)

The sample container must be completely emptied onto a clean dry surface. It is then reduced to small pieces either by using the dry hands or by means of a dry spatula or spoon. Precautions must be taken to avoid loss or gain of moisture. The sample is thoroughly mixed. It is heaped into a cone shaped pile and divided vertically into four quarters. The two opposite quarters are discarded and the process repeated, until a suitable size of sub-sample is obtained.

Preservative

Two (2) drops formalin or two (2) drops of 10/1 (vol/vol) ammonia (Sp. Gr. 0.880) and chloroform mixture in each 16 oz. bottle filled with the prepared sample.

Frequency

Preferably every half hour, hut, in any case, not less frequently than one every hour,

JUICES They should be collected in covered containers of a suitable size. All juice sampling

devices and containers should be kept absolutely clean and sterile. Seamless copper cylinders, 24 in. x 6 in. (diameter) fitted with a conical copper lid in which small holes have been drilled should be adequate. See Figure 4.2.

Fig. 4.2. illustrating container recommended for sampling juice

31

FIRST EXPRESSED JUICE

Sample Collection

Any device which samples the juice other than proportionately across the full width of the first roller is unsatisfactory. A collecting tray, fitted with a centrally located spout discharging over a collecting can closed by a perforated, conical lid will meet the require­ments of sampling.

Preparation (Compositing/Analysis)

At the end of each 30 minutes the full can is replaced by an empty one. The full can is conveyed immediately to the laboratory and the entire catch of juice is screened. The juice is screened to remove quantities of suspended solids through a 40 mesh screen. In the case of samples for refractometer brix, the juice is screened through an 80—100 mesh screen. After screening the sample must be thoroughly mixed by stirring.

After mixing is completed, the sample is ready for analysis or for compositing. The making up of composite samples is a process which requires extreme care and accuracy. It is essential that exactly the correct amount of sample should be placed in the composite bottle each time. The correct amount of sample to be added should be plainly marked on the label of the composite bottle so that no error can arise. The measurement of the volume of sample should be carried out with as much care as is used when making up to the mark in a volumetric flask.

Preservative

0.5 ml saturated alcoholic mercuric chloride per litre.

Frequency

Preferably every half hour.

MIXED JUICE

Collection of Sample

It is essential that the sample be proportional. This can be achieved by hanging a perforated, conical topped copper can under the juice discharged from the juice scale.

Preparation (Compositing/Analysis)

A full sampling collecting can is replaced by an empty one. The full can is then conveyed immediately to the laboratory and the entire catch is screened and mixed. The exact quantity of sample required for the composite is carefully measured out and added to the composite jar. The can is emptied, washed with hot water, placed over a steam jet (if available) and dried ready for use.

Preservative

0.5 ml. saturated alcoholic mercuric chloride per litre of sample.

32

Frequency

The container should be changed at least every 30 minutes. Shorter intervals are to be preferred.

LAST EXPRESSED JUICE

Collection of Sample

Samples are usually taken manually by means of a small copper can attached to the end of a stick long enough to reach across the width of the mill, and, as it is particularly difficult to do this in a large mill. The greatest flow of juice is usually at the ends of the roller because some of the juice extracted by the feed roller flows to the discharged side of the mill in the space between the ends of the trashplate and the top of the roller flanges, needless to say this juice should not be sampled, but only the lesser flows along the length of the roller which are extracted by the discharge roller.

Great care should be taken not to collect feed roll juice, some of which falls on the opposite side of the trashbar to the last roll juice a few inches away.

Sampling should be taken bearing in mind the timing of the sampling of the bagasse, so that both samples are related.

Preparation (Compositing/Analysis)

The sample is taken immediately to the laboratory and the juice is screened and mixed. The exact quantity required for the composite sample is carefully measured out and added to the composite jar.

Preservative

0.5 ml saturated alcoholic mercuric chloride per litre of sample should be added.

Frequency

Not less frequent than every 30 minutes,

CLARIFIED JUICE

Collection of Sample

The juice should be sampled continuously, e.g. by placing a pet cock or small pipe with a valve in the discharge side of the pump or in the pipeline conveying the juice.

Preparation (Compositing/Analysis)

The sample should be taken to the laboratory preferably every hour. The entire catch is mixed and a sample withdrawn for compositing.

Preservative

0.5 ml of saturated alcoholic mercuric chloride per litre of sample.

33

Frequency

The composite sample should be analysed every three hours.

MASSECUITES(A.B.C.)

Each grade of Massecuites should be sampled manually during discharge from the pan, at approximately 25, 50 and 75% of its volume. The first sample should be taken from the first flow. It is important to realise that the composition of massecuites varies from point to within the pan, due to imperfect circulation.

Preservative

Massecuite samples need no preservative.

Frequency

Every strike of each grade.

MOLASSES (A and B)

A representative sample may be taken from the tank. It should be taken from several places because the molasses does not mix readily.

MOLASSES (Final)

Final molasses may be sampled by taking a bleed-line from the discharge line of the final molasses pump, with an adjustable pet cock feeding a small trickle into a sample can which is replaced by another at the curing of each 'C' strike. The pet cock should be regularly cleared with a piece of wire to make sure its bore is not restricted.

Preservative

Molasses samples need no preservative.

Frequency

Every A, B and C strike. Where continuous crystallisation is practised the Final molasses samples are taken every two hours.

SYRUP

This should be sampled continuously by placing a pet cock or small pipe with a valve in the pipe line conveying the syrup. The sample should be taken to the laboratory every hour.

Preservative

Syrup samples need no preservative.

Frequency

The composite sample should be analysed every six hours.

34

SUGAR

(a) Bagged Sugar Sample Container

The container should preferably be constructed of metal and provided with a tight fitting lid. It should be seamless, preferably of stainless steel or copper. Before use, all containers should be thoroughly cleaned and dried.

Collection and Frequency of Sample

A small scoopful of sugar is taken from at least each fourth bag at weighing or a small trier inserted into each fourth bag after closing and the sugar withdrawn placed in the sample container.

Preservative

None is required.

(b) Bulk Sugar

Sample Container and Sampling

A small rotating paddle and a suitable container may be mounted to scoop a portion, off a conveyor belt or out of a stream of sugar dropping into the sugar bin. Sugar cascading off the end of a belt may be made to fall over an auger rotating in an upward turned, half pipe of diameter similar to that of the auger, or a small bucket elevator may be used to sample the sugar travelling in the main conveyor, and, the sample further subsampled by falling over the cone of a typical grain sampler.

When sugar is received into or discharged from trucks or other similar containers, a small volume of sugar obtained by inserting an open, cylindrical can into the falling sugar, at least once per truck, is adequate. The sampling can withdraws 135 gms of sugar per 10 ton truck. Sugar samples being withdrawn in exposed situations should be placed immediately into screw-capped jars or other containers.

Preservative

None is required for sugar, but sugar samples must be stored in airtight bottles. Screw-capped lids should have a sealing rubber gasket or be sealed by plastic adhesive tape. The bottles should be completely filled.

Procedure and Frequency

For the routine control of sugar factories, samples should represent between five and ten tons of sugar.

Sugar from each source entering a bulk sugar store will have a sample withdrawn from each truck load, and then samples composited in such a way that the composite sample represents the weekly deliveries from that source.

Outgoing sugar from bulk stores should be sampled in such a way that a composite sample represents no more than 500 tons.

35

36

CHAPTER V

METHODS OF ANALYSES

Bagacillo

Particle Size

Apparatus

Dilution Balance (accurate to 0.1 gms) Tyler sieves, 20, 28 and 35 mesh 8" diameter Lid and Bottom for the above sieves Procedure

1. Clean all sieves, then dry and weigh each individually. 2. Assemble in order 20, 28 and 35 with bottom. 3. Dry 50 gms of bagacillo as for moisture determination. 4. Weigh 25 gms of dried bagacillo and transfer to 20 mesh sieve. Place lid on sieves. 5. Shake entire assembly for 30 minutes. 6. Re-weigh sieves individually along with contents. 7. Subtract weight of sieve empty from sieve with bagacillo to arrive at weight of

bagacillo.

Express weight of bagacillo in each mesh as % of original weight i.e. 25 gms.

Note Set out below are the opening size in mm of the Tyler sieves and their equivalent in British Standard sieves.

Bagasse

(a) Pol Wet Disintegrator. The Australian designed machine must be built to the correct specifications; the blades should be 6" in length, rotate at 2,800 r.p.m. and must be kept sharp. The bottom blade must not be more than ¾" from the bottom of the container. Preparation must be made for the can to be water cooled if excess heating occurs during disintegration.

37

If replacement units are to be ordered the Jeffco Wet Disintegrator (Model 291) is recommended.

Apparatus

Bagasse disintegrator (Australian design) or Jeffco. Alternative disintegrators are Rietz Varigrator and Waring Blender Industrial Model CB4. (All the above machines are not of the same capacity). Saccharimeter tube 400 m.m.

Conical flask 250 ml. Graduated flask 1.0 litre Dilution balance accurate to 0.1 gms. Beaker flask 200 ml.

Reagents

Home's dry lead; Filter paper medium retention.

Procedure

1. Weigh out 1000 gms of bagasse, well mixed, and transfer to disintegrator pot. 2. Add 10 litres of water to disintegrator pot. 3. Secure pot to disintegrator and run for (40) forty minutes. 4. Pour off approximately 240 mls of extract through a fine wire mesh sieve into a

250 ml. conical flask 5. Cool sample in water bath to room temperature. 6. Clarify with a minimum quantity of dry lead and filter. Do not use more than is

necessary to achieve good clarification and filtration becauie excess lead causes errors in Pol reading.

7. Discard the first 20 mls of filtrate then rinse 400 mm tube three times with portions of filtrate, then fill and take Polariscope reading.

8. Take average of three readings.

The calculation and example

wt of bagasse sample 1,000.0 gms. wt of water added 10,000 gms. Normal weight 26.0 gms. Fibre in bagasse (Avg.) 50.0%

Polariscope reading 1.5

The pol in bagasse

38

Note If 400 mm tube is not available 200 mm tube can be used but reading must be multiplied by 2 (x 2) before applying to above formulae.

(b) Moisture Moisture can be determined by drying in a hot air oven, but it is much quicker and convenient to employ a hot air current, such as in the Dietert Moisture Teller ( or Other Patented machines). This however should be frequently checked against the Oven method.

Apparatus

Double Pan balance accurate to 0.1 gms 4" Moisture Teller pan. (i) Oven Method

1. Weigh out 100 gms of sample onto counterbalanced pan. 2. Place in drying oven at 125-130°C (257-266°F) for 3 hours. When more than

one sample is in the oven observe the following practice. Place the wet sample on the top shelf and move the drier samples to the lower shelves.

N.B. If charring of the sample occurs at (125-130°C) dry in oven at 105°C (221°F) for four (4) hours and there after at hourly intervals until constant weight is obtained.

3. Remove the tray from the oven and weigh quickly to minimise re-absorption of moisture.

Calculation Moisture is the loss of weight by sample. Weight of sample 100 gms. Weight of dried sample 49.8 gms. Loss of weight = 100-49.8 = 50.20 % moisture = 50.20 x 100 = 50.20%

100.0

(ii) Moisture Teller Method

1. Determine weight of sample pan 2. Weigh out 100 gms of sample (50 gm if small pan is used) and place in pan. 3. Place sample pan in moisture teller and run for thirty (30) mins. Moisture teller

must be set at 125°C (257°F). 4. Remove sample pan and weigh while still hot. 5. Heat again for five (5) minutes and re-weigh. The weight is accepted when the

last two are within 0.1 gm of each other (i.e. 0.2%).

Calculation

Moisture is the loss of weight by sample. Weight of sample pan 425.3 gm Weight of sample pan + sample 525.3 gm

39

Weight of dried sample + pan 475.1 gm Loss of weight (moisture) = (525.3 - 475.1)

= 50.2 % moisture is 50.2x100 = 50.2%

100.0

Filter Cake

(a) Fibre

Apparatus 100 Mesh Screen (moisture teller 4" pan) Dilution balance (accurate to 0.1 gm) Moisture Teller

Procedure

1. Weigh moisture teller (100 mesh) pan 2. Weigh 100 gms of filter cake into pan 3. Wash in a gentle stream of tap water until the fibre is completely free of mud

particles. Care must be taken that none of the sample washes over the side of the pan.

4. Drain off all excess water. 5. Dry in Moisture Teller for 30 mins. at 125°C (257°F). Alternatively the sample

can be dried in an oven at 125°C for about three hours. 6. Remove the pan and weigh immediately (to prevent absorption of moisture).

7. Dry for a further 5 mins. and re-weigh. Repeat until constant weight is obtained.

Calculation

Weight of pan = W1

Weight of pan + filter cake = W2

Weight of pan + dried sample = W3

Fibre % Filter Cake = W3-W1X100

W 2 - W 1

(b) Moisture

Apparatus Dilution balance (accurate to 0.1 gm) Moisture Teller Moisture Teller 4" pan Procedure 1. Weigh moisture teller pan 2. Weigh 100 gms of filter cake into pan 3. Dry in moisture teller for 30 mins. at 125°C (257°F). Alternatively may be dried

in a oven at 125°C for three hours. 4. Remove pan quickly and weigh immediately (to prevent absorption of moisture). 5. Dry for a further 5 mins. and re-weigh. Repeat until constant weight is obtained.

40

41

Calculation

Weight of pan - W1

Weight of pan + filter cake - W2

Weight of pan + dried filter cake - W3 Moisture % filter cake = W 3 - W 1 x 1 0 0

W 2 - W 1

(c) Pol Apparatus Mortar and Pestle Nickle dish 200 ml Kohlrausch flask 400 mm Polariscope tube Dilution balance (accurate to 0.1 gm) Reagent - Lead sub-acetate Procedure

1. Weigh 50 gm of prepared sample into a counterpoised nickle dish 2. Transfer to mortar 3. Add 10 mls of lead sub-acetate solution and rub to a smooth paste with pestle. 4. Wash paste into 200 ml Kohlrausch flask and make up to mark with distilled water. 5. Shake well and allow to stand for 5 mins. 6. Filter, discard the first 20 mls of filtrate. Rinse 400 mm Polariscope tube thorough­

ly with portions of filtrate, then fill tube and take polariscope reading.

Calculation % Pol = 1/2 Polarimeter reading The above is based on the assumption that the original sample weight of 50 gms consti­tutes two normal weights with an arbitrary adjustment to provide for error due to volume of the insoluble solids.

Alternative Procedure Using Waring or equivalent Commercial Blender.

1. Weigh 125 gms of filter cake into counterpoised nickle dish. 2. Transfer to Blender 3. Add 20 mls of lead acetate solution and 400 mls of distilled water, cover securely. 4. Run blender at LOW speed for exactly one minute. 5. Transfer contents to 500 ml flask, wash all mud particles from blender container

(care must be taken not to exceed 500 ml). Make up to 500 ml mark with distilled water.

6. Shake well and allow to stand for 5 minutes. 7. Filter, discarding first 20 mls of filtrate. 8. Rinse 400 ml Polariscope tube thoroughly with portions of filtrate, then fill tube

and fake polariscope reading.

Calculation (same as above) % Pol = 1/2 Polariscope reading

Juices

First Expressed, Mixed, Last Expressed, Clarified, Evap. Supply. A: °Brix — by hydrometer

Apparatus

Hydrometer cylinder Brix hydrometer

Procedure 1. Wash out the clean hydrometer cylinder with some of the juice sample. 2. Place the cylinder on a level bench so that the top of the cylinder is at eye-level. 3. Fill the cylinder to overflowing with juice, Allow to stand for 15 minutes until free

of all air bubbles. 4. Carefully lower the clean dry Brix hydrometer into the liquid in such a manner that

no air bubbles cling to the bulb or stem. The sample should overflow the cylinder during this operation so that all air bubbles collected on the surface, are removed. The stem of the hydrometer should only be wetted for a maximum of 2 cm above the point at which it comes to rest.

5. Take the Brix reading at the bottom of the meniscus. This reading is recorded as 'Uncorrected Brix.'

Solids by Drying

Total solids determinations are made when more accurate values are required than those given by refractometer or hydrometer. Comparable results may be obtained by evaporation under vacuum at low temperatures — 65°C or at 105°C in atmospheric oven. Apparatus Analytical balance Desiccator Oven Moisture dishes Sand Glass Rod

Procedure

1. Place approximately 30 gm of sand in a moisture dish. Place a glass rod approxi­mately 50 mm long in the dish. Dry in an oven at 105°C and cool in a desiccator.

2. Weigh the dish with cover. 3. Add enough sample to cover the sand in the dish. 4. Replace the cover and weigh. The increase in weight is the weight of the sample. 5. Remove the cover and mix the juice thoroughly with the sand, using the glass rod.

Do not remove the glass rod from the dish except when stirring. 6. Place the dish, with the cover removed, on the top of the oven and dry until the

the mixture is crumbly.

42

7. Stir with the glass rod three or four times during the preliminary drying so that the material is broken up and the maximum drying surface is exposed.

8. Race the dish and cover, with cover removed, in the oven and dry continuously for 10 hours.

9. Remove the dish from the oven to a desiccator. Replace the cover on the dish and allow to cool.

10. Weigh the dish immediately. 11. The loss in weight is equal to the moisture and the remaining materials equal the

total solids.

Calculation

Weight of dish + sand Weight of sand + sample Weight of sample

Weight of dish + sample after drying Weight of total dry solids Total dry solids

B: Pol Apparatus

Filter Funnel/Filter Paper Beaker and cover glass 200 mm polariscope tube

Reagents - Home's dry lead

Procedure

1. Place approximately 200 ml of juice and not more than 2 gms of Home's dry lead in a closed container and shake thoroughly. N.B. - Excess dry lead will cause an error in pol readings.

2. Pour entire contents on the filter paper. Cover with a cover glass. 3. Reject the first 20 ml of filtrate. Use it to wash out beakers and discard rinsings.

Ensure that filtrate is perfectly clear. 4. Rinse 200 mm polariscope tube with a small quantity of filtrate and discard the

washings. 5. Fill polariscope tube, and with a piece of folded filter paper dry off any liquid on

the end of the cover glasses. 6. Read the polariscope. Take the average of three readings and record. 7. Read % Pol from Table II using the observed reading of the polariscope and the

corrected refractometer Brix reading, e.g. Pol reading = 40.6 Brix = 12.5 Pol = 9.95 + 0.15 = 10.10

= 60.437 gm = 70.452 gm = 70.452 - 60.437 = 10.015 gm = 61.614gm. = 61.614 - 60.437 = 1.177 gm = 1.177 x 100 = 11.75%

10.015

43

C: pH

pH is determined on undiluted juice

Apparatus

pH meter Thermometer

Procedure

1. Check and adjust instrument each day with standard buffer solution. 2. Cool sample to room temperature. 3. Rinse the electrodes and container with a portion of the juice. 4. Fill the container to a depth which will cover the bulb of the glass electrode. 5. Observe the temperature of the solution and adjust if the model has a dial for

temperature correction. 6. Allow the system to come to equilibrium and read the pH. Temperature corrections

between 20°—30°C at pH values between 6—9 are less than 0.1 pH and may be disregarded for control purposes.

7. Wash the electrodes and container with distilled water and fill the container with distilled water.

Ash

Apparatus

Analytical balance Silica or platinum crucibles approximately 125 ml capacity. Desiccator Muffle Furnace Hot Plate Pipette Graduated cylinder Reagents — Sulphuric acid (conc.)

Paraffin or white rnineral oil

Procedure

1. Heat crucible to redness in furnace or over a hot plate. 2. Transfer to a desiccator and allow to cool. 3. Weigh on analytical balance. 4. Transfer about 50 ml sample to crucible and weigh. 5. Add 5 ml of 10% sulphuric acid 6. Evaporate to dryness then increase the temperature until the contents are com­

pletely charred. If sample begins to swell, add a few drops of paraffin oil. 7. Transfer to the muffle furnace and heat to 550°C for five hours. 8. Remove, cool and carefully add 3 ml of 10% sulphuric acid, wetting all the ash. 9. Heat on hot plate until all the sulphuric acid is volatized.

44

10. Transfer to furnace and heat at 550°C for a further two hours. 11. Remove, Cool in desiccator and weigh.

Calculations

Weight of dish + juice = 99.750 gm Weight of empty dish = 42.579 gm Weight of juice = 57.171 gm Weight of dish + ash = 42.986 Weight of ash = 0.407 gm % sulphated ash = 0.407 x 100 = 0.71%

57.171

D:

Sucrose (Borax Method - Tentative)

Apparatus Pipette Volumetric flask Polarimeter 200 mm polariscope tube Reagent - Lead sub-acetate

2.5% Borax solution

Procedure

1. Transfer 50 ml of sample in a 100 ml volumetric flask. 2. Add 20 ml of 2.5% Borax solution and make up to 100 ml with distilled water. 3. Clarify with sufficient dry lead sub-acetate. 4. Read polarisation in a 200 mm tube.

Calculation

% Sucrose = Pol reading

2

Determination of Sucrose in Juice

(Jackson & Gillis Modification No. IV Method)

Apparatus

Pipette 200 ml conical flask 100 Kohlrausch flask (ml) 200 mm water jacketed Pol tube Beaker, funnel; Thermometer; Hot Plate Reagents - Sodium Chloride (231.5 gm/litre)

Hydrochloric Acid (24.31° Brix) Lead sub-acetate (dry lead) powder

45

Procedure

Preparation of Sample 1. Clarify the undiluted juice with dry lead as for Pol determination and filter.

Collect about 200 ml of the filtrate. Determine the refractometer Brix of the undiluted juice.

2. Pipette two 50 ml portion of the filtrate into each of two 100 ml Kohlrausch flask labelled 'A' and 'B' respectively.

Direct Polarisation 3. To the flask labelled 'A' add 10 ml of the solution sodium chloride, make up to

mark, mix well and filter. Collect the filtrate. 4. Polarise the filtrate in the water-jacketed Pol tube at a constant temperature and

record the results.

Inversion (U.S. Custom Method)

5. To the flask labelled 'B' (which contains 50 ml of the original filtrate) add 10 ml of the hydrochloric acid to the cold solution heat to 60°C and hold at that tempera­ture for 10 mins. agitating for the first 3 mins.

6. Cool the contents of the flask quickly and make up the volume to mark with distilled water.

7. Polarise, using the 200 mm water-jacketed tube at the same temperature as before.

Calculations

The calculation does not give the Clerget sucrose immediately, but supplies a 'Polariscope reading' figure P, which is used with the Schmitz's Table (International Scale). P = (A - B) x 100

corrected Clerget Divisor Where: A = direct reading

B = invert reading

1. Determine an uncorrected Clerget Divisor by using the table which relates the

Brix of the juice to the Divisor (Table X). 2. Then deduct 0.07 from the Divisor due to the use of the U.S. Customs method of

inversion instead of the Walker method. 3. Determine the temperature correction to be applied to the Divisor by using the

table which relates the temperature to the temperature correction for the Clerget Divisor (Table XI). Subtract this correction factor from the uncorrected Clerget Division determined in (2) to arrive at the corrected Clerget Divisor.

4. Apply the formula stated above to arrive at a 'Polariscope reading' to be used in the Schmitz's Table.

5. Determine the % sucrose by using the table which relates Pol reading (calculated above) tp °Brix and to % sucrose (Table II).

46

47

E.G. °Brix = 18.1 A at 25.7°C = 60.2 B at 25.7°C = -18.3

A - B = 78.5

Clerget Divisor for 18°Brix = 132.31 (assume that this include the 0.07 correction).

Temperature correction = —3.02 Corrected Clerget Divisor = 129.29 Then,P= 78.5 x 100 = 60.71

129.29 In Schmidtz's Table (International Scale) Polariscope reading = 60.71 °Brix = 18 % Sucrose = 14.57 + 0.17=14.74

DETERMINATION OF SUCROSE AND TOTAL SUGARS

For the determination of sucrose the method relies on the difference between the reducing sugars before inversion and the total reducing sugars after inversion, and is such that:-

% sucrose = (% Total RS after inversion) - (% RS before) x 0.95 (inversion )

The % RS is determined as on Page 49.

The total Reducing sugars after inversion is determined as follows:

BY ACID INVERSION - Layne & Eynon Method

APPARATUS: - Analytical balance Hot plate Timer Water bath at 60° - 65°C Lead ring or clamp Burette (50 ml cap) Volumetric flasks (200 ml, 250 ml) Pipette (25 ml) Boiling flask - pyrex (approx. 400 ml cap) Boiling chips

REAGENTS :-Fehling'sI & II Methylene blue solution (1%) Sodium hydroxide solution (approx. 1M) Phenolphthalein solution Hydrochloric acid (approx. 0.5M) Neutral Lead acetate solution (23.7% Refractometer solids) White mineral oil

PROCEDURE

1. Weigh 10 gm ± 2 mg molasses in a clean tared dish. 2. Add about 15 ml of water and mix thoroughly. 3. Transfer to a 200 ml flask without loss. Add the rinsing from dish and rod to flask

contents. 4. Make up to 200 ml volume. This is a 5% molasses solution. 5. Pipette 25 ml of this solution into a 250 ml volumetric flask and add about 40 ml

of distilled water. 6. Add 20 ml of 0.5M HC1 from a burette, shaking the flask to avoid local high

concentration of acid in the solution. 7. Immerse the flask in the hot water bath and swirl for three minutes to raise the

temperature of the molasses solution as quickly as possible. 8. Clamp the flask in place so that the neck of the flask is in the hot water and allow

to remain further twelve minutes. 9. Remove the flask from the bath and cool under running water.

10. Dilute the solution to approximately 125 ml and add two drops of phenolphthalein. 11. Neutralise the inverted solution by adding 1M sodium hydroxide. During the

addition the flask should be swirled to avoid local high concentration of alkali. 12. Make up the solution to 250 ml. This is now a 0.5% molasses solution.

Titrate this inverted molasses soluiton against 25 ml of Fehling's solution using methylene blue as indicator. See Page 49.

NOTE: Instead of following steps 1-4 for making up the 5% molasses prepare a 1:1 wt:/wt molasses solution. Pipette 10(20) ml into a 100 (200) ml volumetric flask and make up to the mark with distilled water.

CALCULATION

The inverted molasses solution contain no sucrose, therefore the "sugar absent" column of the Layne & Eynon table is applied. Concentration of molasses solution = 0.50% Titration reading = 46.5 ml Invert factor (from tables) = 125.1 mg R.S. Total reducing sugars in 0.5g molasses in 100 ml solution = 100 x 125.1

46.5 = 269.0 mg = 0.2690x100

0.50 % Total Reducing Sugars i.e., Invert factor x 20 = 53.80%

Titration Reading

% Sucrose content of molasses -

Sucrose = 0.95 (% Total Reducing Sugars - (% Original ) ( Reducing ) ( Sugars )

48

Let original RS (i.e. % R.S. before inversion = 16.14%)

Then Rs derived from sucrose = 53.80% - 16.14% = 37.66%

Therefore Sucrose = 0.95 x 37.66 = 35.78%

E:

Determination of Reducing Sugars in Juice

Apparatus

100 mls Kohlrausch flask Conical flask Beaker

Funnel Burette, with stand and clamp Hot plate Tongs Pipette Reagents - 200 mm polariscope tube; Neutral lead (10% solution); Fehling's solution

(1:1 mixture of A and B solutions); Methylene blue indicator; lead sub-acetate; Potassium oxalate (10% solution); Boiling chips; Mineral oil.

Procedure

1. Determine the °Brix of the sample by refractometer 2. Determine the % Pol of the sample 3. To 100 mls of sample in a 100 ml Kohlrausch flask add 10 mls of the neutral lead

solution and filter. 4. Pipette 15 mls of filtrate in the 100 ml Kohlrausch flask, add 5 mls potassium

oxalate, make up to mark with distilled water, filter and fill the burette with the filtrate.

5. Place 10 mls of the mixed Fehling's solution in a conical flask and titrate against using methylene blue as indicator until the end point is reached.

Titration Approximate Titre

1. Place 10 ml of mixed Fehling's solution in the conical flask. 2. Add 15 ml of the prepared solution and heat the contents of the flask until boiling

occurs. 3. Boil for about 15 seconds. 4. Observe the colour of the contents of the flask and estimate how much more

prepared solution is to be added. Then add in increments of 10 mls, boiling for 15 seconds after each addition. Continue adding increments of 10 mls until it becomes unsafe to add a further large increment of solution.

5. Add 4 drops of methylene blue indicator then boil for 1-2 mins. The solution should have a distinct blue colouration.

6. Add the prepared solution 1 ml or less at a time until the methylene blue indicator is decolourized and a bright red colour appears.

49

F:

Suspended Solids

The factory control based on juice weights, the determination of suspended solids in mixed juice is essential because the routine analysis is carried out on the clear juice. Therefore for the calculation of brix and pol entering the boiling house, the gross quantity of mixed juice must be reduced by the suspended solids present leaving net mixed juice. The important points in determination of suspended solids are that a representative sample of the juice must be taken and the sample must be kept well mixed while obtaining the sub-sample for analysis

50

Precaution - Do not add the indicator until the neighbourhood of the end point is reached. During the titration, the boiling must not be interrupted or back oxidation will occur.

Final Titration

1. Add 10 ml of mixed Fehling's solution to the conical flask. 2. Run in prepared solution from the burette until all but 1 ml of the expected titre

has been added. 3. Add a few boiling chips and 3-4 drops solute mineral oil. 4. Heat the flask to boiling and continue boiling for 2 minutes. 5. Add 4 drops of methylene blue indicator to the boiling liquid and complete the

titration within the next minute while boiling is still maintained.

Calculation

Let the titre reading = 20 mls °Brix = 16.0 % Pol = 13.0

Determine the specific gravity by applying the °Brix (16.0) to table, Grams, prepared sample = specific gravity x volume, ml of sample per 100 ml = A

= 1.06508 x 100 = 106.508 Gm Pol per 100 ml of prepared sample = specific gravity x volume, ml of sample per

100 ml x% Pol = B = 106.508 x 13.0 13.846

100 Apply the titre reading and the gm. Pol per 100 ml (B) to table 3 and read off the milli­grams reducing sugar per 100 ml.

Apparatus

Desiccator Analytical balance Drying oven Source of vacuum Buchner funnel - approx. 9 cm diameter Filter flask Filter aid Reagents - 1. Alpha - naphthol 2. Conc. sulphuric acid

Procedure

1. Weigh an oven dried filter paper. (Several papers may be dried and kept in a desiccator ready for use).

2. Weigh 3 grams of oven dried filter aid. 3. Add the filter aid to 100 gms of juice in a beaker and stir thoroughly. 4. Place a Buchner funnel on a filter flask. 5. Fit the oven dried filter paper in the Buchner funnel. 6. Moisten with a few drops of water. 7. Start the vacuum and make paper fit snugly into place. 8. Transfer the mixture to the filter paper and wash any remaining material from the

beaker on to the filter with water. 9. Wash cake with water until a fresh portion of the filtrate fails to show sugar when

tested with a alpha-naphthol solution. (Use approx. 4 x 100 ml quantities of water). 10. Carefully remove the cake and dry in an oven for 3 hours at 105°C. 11. Cool in a desiccator and weigh to constant weight.

Calculation

Weight of dried cake (filter paper + filter aid + suspended solids) = 3.85 g Weight of filter paper = 0.25 g Weight of filter aid = 3.00 g Weight of suspended solids (3.85 - 3.25) = 0.60 g % Suspended solids (0.60 x 100) = 0.60%

100

METHODS OF ANALYSES

Total Dissolved Solids By Refractometer

Apparatus

1. Refractometer 2. Suitable light source 3. Dropper or Rubber Policeman 4. Thermometer

51

Procedure

1. Ensure that the instrument has been set up and checked with air free distilled water at the beginning of each shift.

2. Start the circulation of water several minutes before using the instrument. 3. Open the prism box and rinse the faces with distilled water. 4. Dry the faces of the prism with clean dry tissue paper. 5. Place a drop of juice on the fixed prism. 6. Close and take two readings. 7. Note the temperature. 8. Calculate the mean of the two readings and bring to the standard temperature of

27.5°C by reference to Table I Page 139 . 9. Wash off the prism well with distilled water and dry with clean dry paper tissue

paper.

NOTE: Sugar solutions are corrosive. They should not be allowed to remain in the instrument between readings of various samples. The prism hinges should be washed well with distilled water from a wash bottle, and the hinges and other metal working or exposed parts lightly oiled every few days to prevent corrosion and to ensure smooth operation.

No readings should be accepted as final without being sure that they are not changing with time, i.e. that the solutions have attained equilibrium with the temperature of the instrument.

Calculation

Refractometer Reading I = 14.50° Refractometer Reading II = 14.50° Mean Refractometer Reading = 14.50° Temperature measurement = 30.0°C Correction (Table) = +0.21 Corrected values = 14.71°

MOLASSES

Sucrose - (Jackson & Gills Method No. IV) This method involves determination of sucrose by polarisation before and after inversion with hydrochloric acid. % sucrose = (% invert after inversion - % invert sugar before inversion) x 19

20

Apparatus

1. Polarimeter and tube 200 mm 2. Balance analytical 3. Weighing dish 4. Timer 5. Thermometer

52

6. Water bath maintained at 60°C +1ºC 7. Filter funnel 8. Filtrate receivers 9. Beaker and cover glasses

10. Burette 10 ml 11. Volumetric flasks 100 ml and 500 ml

12. Pipettes 25 ml and 50 ml

Reagents

1. Dry basic lead acetate or Home's Dry Lead 2. Hydrochloric acid (0. 5N) 3. Sodium chloride solution (23.15%) Procedure

1. Weigh 65 g of molasses +2 mg into a clean weighed dish. 2. Add about 50 ml of water and stir thoroughly to produce a uniform solution.

Transfer the solution without loss to a 500 ml volumetric flask. Rinse the dish and add the washlings to the contents of the flask.

3. Add enough water to bring the volume to about 450 ml and mix by gently swirling. Make up to nearly 500 ml and again mix. Let the solution stand for a few minutes to equilibrate with the temperature of the room and then finally make up the

. volume to 500 ml. 4. Transfer the solution to a 600 ml beaker and add about 12-16 gms Home's Dry

Lead. A small quantity of Dry Lead should be added to the solution which is then thoroughly stirred followed by further additions. Additions of large amounts of lead acetate result in the adhesion of particles thus reducing the purification effect.

5. Filter the solution and reject the first 25 ml of filtrate. Precautions should be taken to avoid evaporation of the solution both from the funnel and filtrate receiver.

6. Cover the funnel with a cover glass. 7. Collect at least 200 ml of filtrate. 8. Pipette 75 ml portions into each of two 100 ml volumetric flasks labelled A and B.

Flask A is used for the direct polarisation and Flask B for the invert polarisation. 9. Direct Polarisation - Flask A

Add 10 ml of sodium chloride to the solution in flask A and make up to volume with water. If a precepitate occurs, filter.

10. Rinse the 200 mm polarisation tube with the solution and then take an average of five readings as a basis for calculating the direct polarisation.

11. Invert Polarisation — Flask B Add 10 ml of 0.5N Hydrochloric acid from the burette to the solution in flask B, swirling the contents during addition of the acid.

12. Immerse the flask up to the neck in the water bath maintained at 60°C and swirl the flask continuously for three minutes to uniformly and rapidly heat the solution. Allow the flask to stand stationary for a further 12 minutes ensuring that it is immersed up to the neck and the flask is not in direct contact with any part of the water bath.

13. Remove the flask and rapidly cool the contents by holding the flask under cold

53

running water. Finally make up to 100 ml with water. If precepitation occurs, filter.

14. Read the polarisation as in step 10. Ideally polarisation reading of both solutions A and B should be done at about the same time and under similar temperature conditions.

15. Determine Refractometer brix of original molasses.

Calculation

Weight of molasses per 100 ml solution = 75 x 65 = 9.75 500

Normal molasses contain 26 gm/100 ml Normality of molasses solution = 9.75 = 0.375

26.000

Sucrose % = (P-P1) x 2.667 x 100

132.56 + 0.0794 (M-13) - 0.53(t-20)

Where P = Polarisation as read after instrument correction (reading A) = 7.95 P1 = Invert polarisation as read after instrument correction (Reading B) = - 7.20

2.667 = Factor for conversion of polarisation to normality.

i-e. ( 1 ) ( normality of the molasses solution )

132.56 = Basic Clerget divisor - Table XIII Page 175 M = Gram solids/100 ml molasses solution as polarised

0.0794(M—13)= Factor to compensate for the influence of solids content of the solu­tion on degree of inversion.

t = Temperature (°C) of the solution as polarised. = 20° C M = 9.75 x 85.0 =8.29

100 Polarisations at 27.5°C (t) in 200 mm tubes Direct reading (A) = 7.95 (P) Invert reading (B) = 7.20 (P1)

Sucrose % = (7.95 + 7.20) x 2.667 x 100 = 4040.5 132.56 + 0.0794 (8.29 - 13.00) 132.19 = 30.57%

NOTES 1. It is not possible to quote a fixed weight of lead acetate to be used for defecation.

The amount needed depends on the characteristics of the molasses under test. Generally for blackstrap (final) molasses 6 gm to 8 gm of lead acetate is added for each 26 gm of molasses in solution. On some occasions even more may be required if difficulty is experienced in obtaining the polarisation reading. In some instances the use of extra lead acetate has little effect on the solution colour with the result that a reading cannot be readily obtained using the 200 mm tube. In such instances

54

55

a 100 mm tube should be used and the polarisation multiplied by two before pro­ceeding with the calculation. High Test molasses requires the use of less lead acetate to secure adequate defecation, 3 gm to 4 gm lead acetate is usually sufficient for 26 gm molasses.

Often it becomes difficult to obtain a satisfactory polarimeter reading on the inverted solution (B) due to the intense colour of the solution. Some chemists overcome this obstacle by adding about 0.5 gm of zinc dust to the acid solution. The reaction with the evolution of hydrogen is allowed to proceed for about 10 minutes during which time the solution colour is greatly reduced. The temperature of the solution is adjusted before filling the tube with the supernatent solution. Decolouring carbons must not be used for the reduction of the solution colour.

2. Dilution of dense syrups which contain appreciable proportions of invert sugars may result in mutarotation. This feature applies especially to High Test Molasses which consists of invert sugar. Various means exist for accelerating the comparative­ly slow changes that occur in solution, e.g. by the addition of ammonia or sodium carbonate. The same effect is obtained by permitting the solution to stand for at least one hour from the time of dilution. The method given here depends on allow­ing a period of not less than one hour to elapse between the time of dilution and the time when the direct polarisation reading is taken.

Molasses/Massecuite Separation

It may be deemed necessary to analyse molasses purity at various stages of the crystallization process. The method set out below is suitable.

Apparatus

Massecuite Filter (described in Chapter III) 500 ml Beaker

Procedure

1. Fill apparatus with Massecuite to be checked, after ensuring that it was clean and screens in good condition.

2. Bolt down top securely, connect air line (drain moisture trap) and place beaker in position to catch molasses.

3. Turn on air pressure, increasing gradually up to 15 p.s.i.g. 4. Allow sample to filter until sufficient sample is obtained (less than one hour is

needed).

NOTE: a) Moisture trap must be attached to air line to ensure that molasses is not diluted.

b) Do not allow air to blow through screen as this will increase the molasses density.

Massecuite

Crystal Volume, Apparent

Apparatus

Shrinkage apparatus (discussed in Ch. III).

Procedure 1. Fill extraction cylinder with massecuite and place in position. 2. Take reading of pointer. Be careful to read pointer when arm just touches the

piston shaft without exerting any force. 3. Put weight in position and release. Allow to stand until all movement of the arm

stops (the time needed will vary depending on the type of massecuite being pro­cessed).

The shrinkage factor represents the excess mother liquor in the massecuite over and above the quantity required to fill voids. The apparent crystal volume is the difference between % shrinkage and 100.

Calculation

Initial reading (step 2) = 97 Final reading (step 4) = 71 Shrinkage factor (97-71) = 26 Apparent crystal volume (100—26) = 74%

Note A: - For low grade Massecuite the following is recommended.

1. For good Pan Boiling 40-60% A.C.V.

2. For Charging Crystallizers 60-70% A.C.V.

3. For Charging baskets 75-85% A.C.V.

B: - Apparent and True Crystal Content relationship

Molasses, Massecuite, Syrup

A. By Hydrometer

Apparatus

Dilution Balance (accurate to 0.1 gm)

56

57

Brix hydrometer 40°-50° range Hydrometer cylinder Beaker 2 x 600 ml Thermometer 0-100°C Procedure

1. Counter poise two beakers on the balance. 2. Fill one about 1/3 with molasses and add water to the other beaker until

they balance. 3. Mix the molasses thoroughly to ensure a uniform solution. 4. Pour the diluted molasses into the hydrometer cylinder taking care to prevent

any foam flowing from the beaker into the cylinder. Fill the cylinder to within about 20 mm of the top and allow to stand for 20 mins. Carefully remove any foam from the surface.

5. Ensure that the Brix spindle is clean and dry then pour a small quantity of diluted molasses remaining in the beaker, over the bulb portion of the hydrometer.

6. Insert the hydrometer slowly into the diluted molasses in the cylinder until it comes to rest and then push slowly to l°Brix beyond this point. Raise the hydrometer to release air bubbles trapped beneath the bulb and restore spindle to its original position.

7. Take the hydrometer reading after ensuring that it is free floating and not in contact with the sides of the cylinder.

8. Remove hydrometer, take the temperature reading and apply corrections. (Table I).

Calculation Hydrometer reading = 43.53 Brix Temperature = 32°C Temperature correction = + 0.37 Brix (a) 27.5°C = 43.90 Brix of molasses = 43.90 x 2 = 87.80

B. By Refractometer

Refractometer measurements are based on an effect which is almost entirely created by solids in solution. Suspended solids, dark coloured substances in molasses tend to reduce the sharpness of the boundary line.

Apparatus

Refractometer Light source Plastic rod or glass rod with a piece of rubber tubing on the end. Thermometer O-50°C range. Beaker

58

Procedure

1. Make a 1:1 dilation of the molasses sample. 2. Ensure that the instrument has been checked and reads zero with distilled

water. 3. Transfer a small amount of the 1:1 molasses from the container and apply a

drop to the fixed prism face by means of the rod. Extend the molasses along the face of the prism without touching the surface and avoiding the forma­tion of air bubbles. Close the prisms quickly. Take the refractometer reading.

C. Conductimetric Ash

Conductivity is usually determined on 28.0 Refractometer solids molasses.

Apparatus

Dilution Balance (heavy duty) Conductivity meter Refractometer

Procedure

1. Determine refractometer solids of sample. 2. Weigh 200 g of sample on heavy duty balance. 3. Calculate the amount of water needed to be added to dilute to 28.0 refracto­

meter solids.

Ref. sol, of sample = Factor Desired Ref. sol. of dil. sample Factor x 200 g = Total weight of diluted sample

E.g. Refractometer solids of original sample = 87.0 Factor = 87.0 = 3.11

28.0

Total weight of diluted sample = 3.11 x 200 = 622 g 4. Add distilled water to bring total weight to 622 g. Mix thoroughly. 5. Fill the cylinder of the conductivity cell about 3/4 full with molasses solution

and immerse the electrodes. Let stand for about 1/2 min. Pour out this solution and refill the cell with a fresh portion of molasses solution ensuring that the thermometer bulb is covered.

6. Note temperature of solution in cylinder and adjust the temperature com­pensator accordingly.

7. Insert resistance plug in resistance unit making sure that plug is tight to ensure contact — turn switch to Specific Conductance.

8. Read off and record value.

Calculation Reading = 1.75 Resistance Unit = 104

Specific Conductance = 1.75 x 104 micromhos

D. Determination of Reducing Sugars in Molasses

Apparatus

100 ml Kohlrausch flask Conical flask Beaker Funnel Burette, with stand and clamp Hot Plate Tongs Pipette Reagents - 200 mm polariscope tube; Neutral lead (10% solution); Fehling's

solution (1:1 mixture of A and B solution); Methylene blue indica­tor; Potassium oxalate (10% solution).

Procedure

1. Determine the % Pol of the sample 2. Make up a 1 - 1 dilution of sample. 3. Pipette 10 mls of the prepared sample in the 100 ml Kohlrausch flask, then

5 mls of the neutral lead solution make up to mark, filter and collect filtrate.

4. Pipette 20 mls of filtrate into a 100 ml Kohlrausch flask add 10 mls potas­sium oxalate solution, make up to mark, filter, collect second filtrate and transfer to the burette.

5. Add 10 mls of the mixed Fehling's solution in a conical flask and titrate against the second filtrate using methylene blue as indicator until the end point is reached.

Calculation Let the titre reading = 22.0 mis gm Pol per 100 ml in prepared sample = % Pol x (vol, ml of prepared sample

÷ 100 = A

Apply the titre reading and the gm Pol per 100 ml (A) to table and read off the milligram reducing sugar per 100 ml.

Table VI

59

60

Molasses, Massecuite and Syrup

Ash (Sulphated)

Apparatus

Platinum dish Analytical Balance Furnace (muffle) Desiccator Hot Plate 50 ml Graduated cylinder

Reagents

Sulphuric acid (concentrated)

Procedure

1. Heat platinum dish to redness in furnace (or over burner) 2. Transfer to a desiccator and allow to cool to room temperature. 3. Weigh dish with analytical balance and record. 4. Weigh 3 or 4 gms of sample into platinum dish and record. 5. Moisten sample with 0.5 ml concentrated sulphuric acid and heat gently over hot

plate until sample is carbonized. (Raise temperature of hot plate gradually to avoid spattering of sample).

6. Transfer to furnace at 550°C (1022°F) (dull read heat) for five hours. 7. Remove dish from furnace and cool, then moisten with a few drops of concentrated

sulphuric acid. 8. Reheat in furnace at 800°C for 10-15 minutes. 9. Cool dish, first in air, then in desiccator to room temperature. 10. Weigh dish with ash content and record.

Calculation

Weight of dish and sample = 44.8369 gm Weight of dish = 41.7443 gm Weight of sample = 3.0926 gm Weight of dish + ash (after incineration) = 42.1433 gm Weight of ash (42.1433 - 41.7443) = 0.3990 gm

Pol (Normal weight method)

The water purity method is adequate for Pol determination of Syrup, Massecuite and Molasses. This method should not be used for FINAL MOLASSES, instead the NORMAL WEIGHT METHOD must be used.

NOTE: A preliminary test should be made at the commencement of the crop to determine the normality of the solution which can be read in a 100 mm polar-iscope tube. In most cases, twice the normal weight of a.l:l dilution will be found satisfactory.

61

Apparatus

Analytical Balance Dilution Balance 600 ml Beakers x 2 200 ml Kohlrausch flask 200 mm polariscope tube 50 - 55 ml volumetric flask Filter paper and funnel

Reagent

Blue litmus paper 20% acetic acid solution Horne's Dry Lead

Procedure

1. Prepare a 1:1 dilution mixture of molasses by using dilution balance and 600 ml counterpoise beakers.

2. Weigh out 52.00 gm of this solution on Analytical Balance in nickel dish. 3. Transfer to 200 ml kohlrausch flask, take care to wash all molasses into flask with

the minimum quantity of distilled water. 4. Make up to 100 mls with distilled water and dissolve all molasses by gently swirling

flask in hand. 5. Add water slowly to mark, take care too that it becomes incorporated in the

solution before finally adjusting to volume. 6. Add 14 gm of Horne's dry lead (6-8 gm per normal weight), mix thoroughly and

filter. Use first 10 mls of filtrate to rinse beaker and discard. 7. Rinse 50-55 ml volumetric flask with approximately 5 mls of filtrate, then transfer

50 mls using pipette. 8. Acidify solution to litmus using 20% acetic acid, shaken vigorously then made up

to 55 ml mark before filtering. 9. Fill 200 mm polariscope tube and read. Take average of three readings.

Calculation

If Pol reading = 9.2 %PoI = 9.2x2.2

= 20.24

NOTE: If 100 mm tube is used % Pol = (Pol reading x 4.4)

Periodic side titrations to determine the quantity of acetic acid required are necessary.

The addition of acetic acid is associated with the relatively high proportion of fructose in final molasses. Lead in solution combines with fructose to give a soluble compound of low optical rotation, which is split by acetic acid and thus restoring the optical rotation of the fructose.

62

Syrup, Molasses and Massecuite for stock purpose are analysed in the same manner. For syrup, one normal weight in 100 ml will be satisfactory, using 0.75 — 1.0 gm Home's dry lead per normal weight and polarizing in a 200 mm tube. For molasses and Massecuite the required normality must be determined in the analyses of all products under this sub-heading, its essential that once the conditions have been fixed they must be adhered to. The reason for this is that over leading must be avoided.

E. Determination of Water Purity of Molasses. Massecuite and Syrup

Procedure

1. Dissolve the sample in distilled water and dilute the solution to any conven­ient brix between 10° and 15°.

2. Mix thoroughly, allow to stand until all air is removed and determine the brix by hydrometer or alternatively by refractometer.

3. Take a portion of the solution prepared in (1) and add:

(a) Sufficient Horne's dry lead sub-acetate to clarify. (b) a spoonful of dry kieselguhr

then filter and collect the Filtrate. 4. Determine the mean saccharimeter reading using a 200 ml polariscope tube.

Calculation

The % Pol is read off table 11 using the mean saccharimeter reading and tempera­ture corrected °Brix by refractometer or the uncorrected °Brix reading by hydrometer.

% Pol x 100 = Purity

°Brix

Sugar

A. Ash

Incineration method (Gravimetric)

Apparatus

Analytical balance Desiccator Platinum (or Quartz) dish 100 - Muffle Furnace 125 ml capacity Hot Plate

Reagents - Sulphuric acid (conc.)

Procedure

1. Heat Platinum dish to redness in furnace or over burner. 2. Place in desiccator and allow to cool. 3. Weigh the dish on analytical balance. 4. Weigh 5.0 gm of sample into Platinum dish.

5. Moisten sample with 0.5 ml of concentrated sulphuric acid. 6. Heat gently over hot plate until sample is carbonized. 7. Place in Muffle furnace pre-heated to 550°C (1022°F), dull red heat, and

incinerate until all carbon is burnt off. (This may require as much as 5 hours). 8. Remove from furnace, cool, and carefully add a few more drops of the con­

centrated sulphuric acid. 9. Reheat in Muffle furnace at 800°C (1472°F) for 15 minutes. 10. Remove from furnace and cool in desiccator to room temperature. 11. Weigh Platinum dish with sulphated ash. Calculation and E.g. Weight of dish (empty) = 48.3762 gms Weight of dish + sugar = 53.6230 gms Weight of sugar = 5.2468 gms Weight of dish + ash = 48.4056 gms Weight of ash = 48.4056 - 48.3762 = 0.0294 gms

%Ash = 0.0294 x 100 = 0.56% 5.2468

B. AFFEMATION PROCEDURE Apparatus Reagents Mixer Anhydrous Methanol Centrifugal Machine 64.0° Brix Syrup

Procedure 1. Place 1000gm. of well-mixed raw sugar in the mixer. Turn the mixer on to

low speed. 2. Gradually add 380 ml. of 64.0° Brix granulated sugar syrup at room tempera­

ture. (A 64.0 °Brix syrup made from high quality sugar may be substituted for a syrup made from granulated sugar.) The syrup is added slowly from a dispensing burette and must be added at a uniform rate for approximately 4 1/2 minutes.

3. The raw sugar and syrup continue to mix for an additional one minute. The total mixing period is 5 1/2 minutes.

4. Transfer the entire magma at once from the mixer to the Laboratory Centri­fugal Machine.

5. Bring the Centrifuge up to 3000 rpm in 15 seconds and spin at 3000 rpm for exactly two minutes.

6. Remove the sugar from the basket and spread it on a clean surface in a thin layer not to exceed 1/4 inch thick.

7. Immediately after spreading take representative portions totalling approxi­mately 100 gm. from all areas in the spread layer and immerse in 75 ml. of anhydrous methanol contained in a 250 ml. extraction flask. This portion of the sample is to be used for the grain size test.

8. The remaining portion of the spread which is to be used for colour is mixed periodically (by hand) during drying so that at the end of drying, the sample is well mixed.

9. If sample is not to be tested immediately, it should be stored in sealed jars.

63

C. Colour

Apparatus

Spectrophotometer (a 560 nm Pyrex sintered - glass filter (porosity F) for white sugar Source of vacuum Buchner type funnel Filter paper

Reagents - Dilute hydrochloric acid (0.1N); Dilute sodium hydroxide solution

(0.1N); Kieselguhr (analytical grade).

Procedure 1. Prepare a solution of the sugar to be tested using distilled water. Below are

the concentrations:-

(a) White sugar -- 50% solids (b) Raw Sugar - as high as practicable, consistent with reasonable filtra­

tion rates and cell depth. 2. Filter the solution under vacuum with analytical grade Kieselguhr (1% of

sugar weight) over filter paper. The first portion of the filtrate should be discarded if cloudy. (While sugar solution and light coloured liquors should filtered through Pyrex sintered glass porosity F without addition of fil­ter aid).

3. Adjust the pH of solution to 7.0 +0.2 with dilute Hydrochloric acid (HCl) ana/or caustic soda (NaOH). (Do not adjust the pH of white sugar solution).

4. Remove entrained air under vacuum. 5. Race the solution in absorption cell. Determine the attenuancy at 560 nm in

a spectrophotometer using distilled water as a zero colour reference standard (wavelength of 560 nm for White Sugar).

NOTE:- The length of the cell should be chosen so that the instrument reading will be between 10 and 90% transmittancy.

6 Calculate the attenuation index of the solution as follows:

Total Colour (Attenuation) at 560 nm = 1000 x optical density (concentration of solution gm/mm) x (cell size in cm)

If spectrophotometer is calibrated fn transmittancy units then:-Total Colour (Attenuation) at 560 nm

= 1000 ( - log T) (concentration of sol. gm/ml) x (cell size in cm)

NOTE:- It is important that in neutralizing the solution no more than 10 drops of acid and/or base are used. Total colour is in ICUMSA units.

64

D. Grain Size Apparatus Extraction Flask Vacuum Flask Sieve Shaker Tyler # 14, 20 and 28 Mesh Sieves

Reagents Ethyl Ether Anhydrous Methanol

Procedure

1. The flask containing the sample previously collected for grain size test is swirled vigorously for two minutes so that the sugar is well mixed with the solvent.

2. Drain the solvent from the flask. After the solvent has drained, break vacuum, shake the extraction flask and place back over the vacuum flask. Repeat two or three times.

3. After draining, return flask to an upright position, add 50 ml. of anhydrous methanol and repeat swirling and draining procedure.

4. Repeat swirling and draining procedure twice, using a 50 ml. portion of ethyl ether time. (Caution: Do not use near open flame.)

5. Place drained sugar on absorbent filter paper and allow to air dry. No lumping or caking should occur on drying. Soft conglomerates if any, should be broken by gentle hand pressure. If lumping is observed after drying, discard the sample. Begin again, starting with the affination procedure.

6. Weigh (to ± 0.1 gm.) the entire amount of affined raw sugar which has been washed with solvent and dried.

7. Assemble the screens with a 14 mesh tyler as the top screen, followed by the tyler 20 and tyler 28 mesh screens. A pan, and additional screens if neces­sary, are added to make up a set of screens that will fit on a mechanical shaker.

8. Place the weighed amount of the 14 mesh tyler screen. 9. Place the set of screens on a mechanical shaker and run for five minutes. 10. The grain size, is reported as the percentage of sample passing through the 28

mesh tyler screen, determined as follows:

weight through 28 mesh screen x 100 = % grain size starting weight

65

E. Moisture

It is important for this routine determination that the drying agent in the desiccator be changed regularly and always kept in a highly active state. Oven Method Apparatus Analytical balance Desiccator Oven

Alurninium dishes (with close fitting cover)

N.B. - Dishes should be dried at least one hour at 100°C (212°F) prior to use.

Procedure

1. Transfer the moisture dish and cover to the desiccator and cool. 2. Weigh dish with cover. 3. Weigh 5 gm of well mixed sample and transfer to dish and replace cover. 4. Immediately place in oven pre-heated to 105°C (221°F) for three hours

(cover must be in oven but not covering sugar). 5. Remove dish from oven, replace cover, and transfer to desiccator at once. 6. Cool to room temperature and weigh.

Calculation

Weight of dish - = 14.3689 gm Weight of dish + sugar = 19.4387 gm Weight of sugar = 5.0698 gm Weight of dish + dried sugar = 19.4245 gm Loss of weight (19.4387 - 19.4245) = 0.0142 gm % moisture = 0.0142 x 100 = 0.28%

5.0698

•

66

F.Pol Apparatus

Analytical balance 100 ml Kohlrausch flask (calibrated at 27.5°C) Polariscope 200 mm tube Whatman No. 1 18.5 cm or equivalent filter paper

Reagent - Home's dry lead

Procedure

1. Weigh 26.00 gm of sugar into nickel dish (to the nearest 10 mg). 2. Wash into 100 ml Kohlrausch flask, being careful to wash all sugar from

nickel dish and neck of flask. Use just enough water to half fill the flask. (i.e. 45-50 ml).

3. Dissolve sugar completely by gently swirling flask either by hand or suitable machine.

4. Make up volume to 90 ml with distilled water, and rotate flask gently to mix contents completely.

5. Fill to mark with distilled water. Carefully remove any drops of water in the neck of the flask by absorption on filter paper.

6. Clarify by using the minimum quantity of Home's dry lead (not to exceed 1.0 gm).

7. Shake flask thoroughly end over end, allow to stand for 5 mins, shake again and pour entire contents into filter paper and funnel of suitable size. Cover filter paper with watch glass.

8. When 25-30 mls of filtrate has collected, use to rinse inside of filtrate beaker and discard. Note: Filtrate can only be returned to the funnel if it is cloudy and if funnel is covered with a watch glass during the filtering operation.

9. After rinsing filtrate jar, collect sufficient filtrate to carry out three washings of 200 mm Polariscope tube before filling.

10. Fill 200 mm Polariscope tube and take average of five readings.

Prior to use, the polariscope tube must be tested as follows:-Fill with distilled water and place in Polariscope trough. Reading must be the same as when tube is empty. This precaution is necessary after cleaning, changing or tightening the cover glasses.

In order to avoid changes in temperature of solution, during the reading the tube (filled with solution) must be left in the trough of polariscope for 10 mins. During this period the tubulure of the tube is covered with a small watch glass.

67

G. Dextran

Apparatus

Oven or water-bath maintained at 55°C. 100 cm3 stoppered measuring cylinders. Membrane filtration apparatus and 0.45 micron Millipore membranes and pre-filters. 25 cm3 volumetric flasks. Spectrophotometer capable of operating at 720 nm wavelength, with matched pairs of 40 mm and 10 mm cells.

Reagents

—Amylase enzyme Ion exchange resins Equal weights of Amberlite resins IR-45 (OH form) and IR-120 (H form) are mixed. Both resins should be dry, 14—52 mesh size and of Analytical grade. The mixture is washed with at least twice its weight of distilled water and drained dry. It is then treated with acetone for no longer than 2 minutes by just covering the resin twice and gently sucking dry. Finally it is dried a+ 30°C. Trichloracetic Acid, 10 g/100 cm3. Denatured anhydrous alcohol.

Test Procedure

1. 23.5 grams of whole raw sugar are weighed and dissolved in 35 cm3 of dis­tilled water in a suitable beaker or flask.

2. 0.05 g of —amylase starch-removing enzyme is added to the solution which is incubated at 55°C. for 1 hour in an oven or water bath with agitation every 15 minutes.

3. 10 g of the mixture of ion-exchange resins are added and stirred for 30 minutes. At the end of this period the resin is removed by passing the mixture through a coarse filter, filterate and washings being collected in a 100 cm measuring cylinder.

4. The volume in the cylinder is made up to 100 cm3 with distilled water, and then 10 cm3 of trichloroacetic acid added (to remove protein). The cylinder is stoppered and shaken.

5. The contents of the cylinder are filtered through a 0.45 μm Millipore mem­brane with a pre-filter pad, using the first runnings to rinse the funnel and flask. At least 30 cm3 of filtrate are collected.

6. 12.5 cm3 of filtered solution are pipetted into each of two 25 cm3 volume­tric flasks, a "sample" flask (designated A) and a "control" flask (designated B).

68

7. To the sample flask A is added anhydrous alcohol dropwise from a burette while swirling the flask until the 25 cm3 mark is reached. The stoppered flask is inverted gently several times and allowed to stand at room tempera­ture for 60 ± 2 minutes while the haze develops.

8. To the control flask B distilled water is added with swirling to the 25 cm3

mark.The stoppered flask is shaken. 9. One of the matched pair of 40 mm cells is filled with distilled water and the

other with the control solution. After zeroing the spectrophotometer at 720 nm with the cell containing distilled water, the absorbance of the control solution is measured (B). The cell is then emptied and cleaned.

10. At the expiration of the 60 minute period, the cell is filled with the sample solution and its absorbance measured (A) after zeroing the spectrophoto­meter against the distilled water cell.

11. If the absorbance of the sample exceeds 0.7 in value, both the sample and control solutions should be re-read in 10 mm cells without delay, after zeroing the instrument with a 10 mm cell.

5. Calculation The results are expressed as absorbance due to dextran haze in a 50 mm light path. Thus if 40 mm cells are employed

Dextran = (A-B) x 1.25 x 1000 milli-Absorbency Units (M.A.U.)

With 10 mm cell

Dextran = (A-B) x 5 1000 M.A.U. H. INSOLUBLE MATTER

Apparatus

Funnel with 120 mesh screen Centrifuge Centrifuge tubes - 2 x 100 ml graduated Glass rod

Procedure

1. Dissolve 25 gms of a well mixed sample in about 60 ml of cold distilled water. 2. Filter through the 120 mesh screen into a 100 ml graduated centrifuge tube. 3. Wash the material retained by the screen into the other centrifuge tube with

distilled water, and make up to 100 ml volume with the washings. 4. Centrifuge both tube for exactly 7½ minutes at 1000 r.p.m. 5. Level the surface of the sediment with the thin glass rod. 6. Repeat the centrifuging procedure. 7. Remove the tubes from the centrifuge and note the volume of sediment in each. 8. Refer to the following table to obtain C, the 'cush-cush' (retained by 120 mesh)

and M the 'mud' (particles passing 120 mesh). This gives insoluble matter in the sample, directly as mg/100 g.

Example of Calculation

Volume of C,'cush-cush' = 0.075

69

Volume of M, 'mud' = .25 Equivalent'cush-cush' = 14mg/100g. Equivalent'mud' = 158mg/100g Insoluble matter = 172mg/100g

Weight/Volume Relationship for Insoluble Matter in Raw Sugar

70

Equivalent weight of 'Cush-Cush'

'C (Mg./l00g Sugar)

_ 5 9

14 18 23 27 32 36 40 45 54 63 72 81 90

Volume of Centrifuges Sediment from

(Ml)

less than 0.025 .025 .05 .075 .10 .125 .15 .175 .20 .225 .25 .3 .35 .4 .45 .5

25g Equivalent weight

of 'Mud' 'M'

(Mg./100g Sugar)

_ 16 32 47 63 79 95

110 126 142 158 190 220 250 282 315

'C' = Volume (from 25g)x 180 'M' = Volume (from 25g) x 630

CHAPTER VI

SPECIAL ANALYSES

Cane: - Determine % Pol in Open Cells

Sampling and Sub-sampling

The difficulty of obtaining representative samples is the biggest hurdle to be overcome in direct cane analyses. EXTREME CARE AND DILIGENCE must be exercised in collecting and preparing samples, as, loss of juice and fibre particles is a common source of error and must be kept at a minimum.

The prepared cane taken from the carrier chute just before #1 mill is the most suitable sampling point. The sample should be from the entire width of the carrier in one motion.

Apparatus

Bagasse Disintegrator 3 gallon tumbler 400 mm Polariscope tube Conical flasks 250 ml Beakers 500 ml

Reagent

Home's dry lead

Procedure

1. Sample approximately 25 lbs prepared cane from chute to # 1 mill. 2. Chop any large pieces of cane present in sample cleanly with sharp blade into 2 in.

— 3 in. lengths and include in sample. 3. Cone and quarter sample carefully and divide into two (2) portions.

4. Treat each portion as follows:

Portion I

1. Weigh 1000 gms of prepared cane into container of wet disintegrator. 2. Add three (3) litres of water. 3. Disintegrate for 45 minutes. 4a. Pour off approximately 240 mls of extract through a fine wire mesh sieve into a

250 ml conical flask. 4b. Cool sample in water bath to room temperature. 5. Clarify with a minimum quantity of dry lead acetate and filter. 6. Discard the first 20 mls of filtrate, then rinse 400 mm tube three times with

portions of filtrate; then fill and take Polariscope reading. 7. Take average of three readings (A)

71

Portion II

1. Weigh 1000 gms of prepared cane and place in tumbler. 2. Add four (4) litres of water. 3. Roll for ten (10) minutes. 4. Pour off approximately 240 mls of extract through a fine wire mesh sieve into a

250 ml conical flask. 5. Clarify with a minimum quantity of dry lead acetate and filter. 6. Discard the first 20 mls of filtrate, then rinse 400 mm tube three times with

portions of filtrate; then fill and take Polariscope reading. 7. Take average of three readings. (B)

Calculations i) Derived ratio R = B

A ii) Determine % fibre in cane (F) on sample used for wet disintegration (i.e. Portion I

at stage (4)), unless otherwise known.

% Cell Breakage = 400 R

4- R - (1.25F/100)(1 - R )

Cane: - Determination of Stateness

Apparatus: 100 ml measuring cylinder 100 ml beaker Filter funnel Reagents - 96% alcohol

Procedure

1. Obtain a sample of mixed juice 2. Filter and place 50 ml in a 100 measuring cylinder. 3. Fill to the mark with 96% alcohol. 4. Shake vigorously and allow to settle for 30 minutes.

Results

This causes precipitation of gums and polysaccharides produced by staling of the cane. If the percentage sediment is less than - 10% — cane is fresh.

- 10 — 20% - cane is becoming stale. - Over 20% - cane is over 5 days old.

IT IS NECESSARY TO ADJUST THIS FORMULA TO YOUR LOCAL CONDITIONS.

72

Evaporator

Cleaning Solutions

For efficient running, Evaporators and Vacuum Pans have to be cleaned at regular intervals either chemically or mechanically. An important factor in good cleaning tech­niques is the monitoring of strengths of the solutions used; Regular checks have to be made to ensure that weakened solutions are brought back to strength. The following analyses are set out for this purpose.

A. ACID (Determination of Strength)

Commercial hydrochloric (muriatic) acid (1.16 sp.gr & HC1)

Apparatus

50 ml Burette 20 ml Pipette

Reagents

I. N Sodium Hydroxide solution Phenolphthalein indicator

Procedure

1. Pipette 20 mls of the acid solution into a 250 ml conical (Erlenmeyer) flask and add 100 ml of distilled water. NOTE: More than 20 mls of acid will be needed if less than 2% solution.

2. Add three drops of phenolpthalein and titrate with I.N. NaOH solution until pink colour just appears.

Calculation and Example

One (I) ml I.N. NaOH is equivalent to 0.03647 gm HC1.

Titration readings 10.6 mls.

20 mls of acid solution required 10.6 mls of I.N. NaOH 10.6 x 0.03647 = 0.3866 gm of HCl in 20 mls solution. i.e. 0.3866 x 100 = 1.93 gms HC1 per 100 mls solution

20

B. ALKALINE (determination of strength)

The approximate concentration of a freshly prepared solution may be determined from the density (or brix) by referring to Table IX, however, used solutions CANNOT be treated likewise due to accumulation of soluble materials from the scale.

The method set out below is designed to determine Total Alkalinity since a mixture of Caustic Soda (NaOH) and Soda Ash (Na2 CO3) is normally used.

73

Apparatus

5 ml Pipette Hot Plate 100 ml Graduated cylinder 50 ml Burette 500 ml Conical (Erlenmeyer) flasks

Reagents

I.N. Sulphuric Acid solution Barium Chloride Solution Methyl Orange Indicator Phenolphthalein Indicator

Procedure

1. Pipette 5 ml of cleaning solution into each of two 500 ml conical flasks and and approximately 200 ml of freshly boiled and cooled distilled water to each.

2. Add three drops of methyl orange and titrate rapidly against I.N. Sulphuric Acid solution until colour change occurs (green to orange). Take burette reading.

3. Using second flask add one ml of sulphuric acid less than required for step 2 (do not add indicator).

4. Cover flask and heat the contents on hot plate to boiling. Continue boiling gently for five minutes.

5. Cool to room temperature, add three drops of methyl orange and titrate to the exact end point, stirring well, add acid dropwise to achieve sharp colour change.

Calculation and Example

Total alkalinity is expressed in terms of Na20 one ml of I.N. Sulphuric acid is equivalent to 0.031 gm Na20.

Titration reading 41.6 ml. Total alkalinity = 41.6x0.031 = 1.290 gm in 5 ml sample.

C. Steam Side Cleaning

The solutions and method set out below is designed to clean the steam side of calandria during the out of crop. Keeping the steam side clean is as important as cleaning the juice side (though it is not done as often).

i) Factories using steam engines extensively can soak steam side of calandria with diesel oil for entire out of crop,

ii) For other factories, the following is recommended.

74

Reagents

Caustic Soda (NaOH) Potassium Permanganate (KMn O4) Muriatic Acid (1.16 sp. gr HC1) Ferrous Sulphate (Fe SO4) NOTE: All industrial grade reagents.

Procedure

1. Prepare solutions of 72 lbs NaOH and 72 lbs KMn O4 per 1000 gallons water and heat to 60°C (140°F).

2. Fill calandria to be cleaned and heat with steam to 100°C (212°F) for at least 24 hours.

3. Discard solution and rinse calandria thoroughly. 4. Mix with cold water and inject into calandria solution of six carbouys of

muriatic acid and 60 lbs of Ferrous Sulphate in 1000 gallons of water. 5. Heat (in calandria) with steam to 94°C (200°F) for 45 minutes. 6. Run out solution and rinse thoroughly with clean cold water.

This cleaning is recommended periodically, but a well regulated factory once per year is too often.

FLUE GAS ANALYSES

Excess Air

For the complete combustion of boiler fuels (crude oil and or bagasse) to carbon dioxide (CO2) and water (H2O), more air is required than theoretical considerations indicate. The quantity needed above the theoretical is called EXCESS AIR. All flue gases thus contain "excess air" but, this must be carefully controlled at the minimum which contains that quantity of oxygen (O2) required for complete combustion. This is important for efficient boiler operations as excess of air passing through the furnace absorbs heat which is lost in flue gasses. On the other hand insufficient "excess air" results in incomplete combustion with the appearance of carbon monoxide (CO) and very often smoke in the flue gas.

Theoretical air is the calculated quantity containing just sufficient oxygen to combine with the carbon, net hydrogen and sulphur of the fuel to form carbon dioxide, water vapour and sulphur dioxide (fuel oil).

The results of the analyses described below based on ORSAT or equivalent apparatus and their interpretation are based on the quantity of carbon dioxide (CO2) present in flue gas. More modern apparatus (e.g. Zirconium oxide cells) analyses oxygen (O2) present in flue gasses continuously and control damper settings automatically. NOTE: Such equipment analyses on a wet basis and is sensitive to water vapour in flue

gasses. Allowance must be made for this if the unit is used on bagasse fired boilers.

75

Apparatus

Orsat or Equivalent (See chapter III)

Reagents

Potassium hydroxide (KOH) 20% solution Alkali solution of pyrogallic acid Acid solution of cuprous chloride (See chapter VIII)

Procedure

1. Fill absorption pipette (to point "A") with freshly prepared reagents, after ensuring that all needle valves and rubber hoses and connections are free of leaks.

2. Fill the measuring burette with more than 100 units of flue gas by lowering the levelling bottle and placing the sample pipe suitable in flue duct.

3. Expell the excess flue gas through the three way petcock leaving exactly 100 units in measuring burette at atmospheric pressure, then close petcock.

4. Force the entire volume of air info the #1 (CO2) absorption pipette by (a) opening the needle valve and raising the levelling bottle, then allow to stand for half minute.

5. By lowering the levelling bottle allow the reagent in #1 absorption pipette to return to the original level (mark "A"). Hold levelling bottle so that water level is equal to that in measuring pipette. Take reading. The quantity of CO2 absorbed, is the difference between the original volume (i.e. 100 units) and the reading at the end of step 5.

6. Repeat steps 4 and 5 until a constant reading is obtained. 7. The flue gas sample remaining is now forced into #2 absorption pipette (O2) as

in step 4 and step 5.

8. Repeat step 7 until a constant reading is obtained. The reading on the measuring burette is now the sum of the percentage of CO2 and the percentage of O2 in original flue gas. The O2 percentage is found by subtraction.

9. The remainder of the flue gas sample is now forced into #3 absorption pipette

(CO) as in step 4 and 5 and the quantity of CO in original flue determined.

The remaining flue gas after all determination is assumed to be nitrogen (N2). 10. To ensure that the analyses have been correctly done the flue gas is expelled and the

oxygen (O2) contained in a 100 unit volume of air is carried out. CARE MUST BE TAKEN TO KEEP SAMPLING PIPE AWAY FROM CARBON DIOXIDE (CO2) and or CARBON MONOXIDE (CO) sources. Result should be 21%. If this is off by more than ½%, check solutions and apparatus and repeat analyses. The results obtained are in % by volume on a dry basis. The flue gas sample is saturated with water vapour at all times, but the water jacket surrounding the measuring burette keeps the sample at a constant (room) temperature during the analyses. While there is always water vapour present, when the sample volume decreases the volume of water vapour also decreases to maintain the same partial pressure of water vapour. Thus the water vapour bas no effect on the analyses and the results are exactly as if dry gas analyses had been done.

76

Excess Air Calculations

If CO2 is the % carbon dioxide determined in flue gas by gas analyses the excess air is calculated by the formula.

Excess = 20.3 x 100 - 100

CO2 (determined)

Example: If analyses gives CO2 is 16% by volume

Excess air = (20.3 x 100 ) - 100 = 126.9 - 100

(16 )

= approx. 27%

% C02 to % Excess Air

Based on Flue gas at 500°F and 50% bagasse moisture.

%CO2

20.3 17 16 15 14 13 12 11 10

% Excess Air

0 19 27 35 44 56 68 84

102

77

Oxygen

Nitrogen

Composition of Air (dry)

% by Weight % by Volume

23.15

76.85

20.84

79.16

Heat Value per Pound of Bagasse, Flue gas at 500°F

% Bagasse

Moisture

45 46 47 48 49 50 51 52 53 54

Theoretical Air

required

3326

3241

3160

3077

2993

2910

2829

2744

2664

2582

50%

3169

3087

3007

2928

2851

2767

2689

2607

2528

2450

Excess Air

100%

3012

2933

2856

2779

2700

2624

2548

2469

2393

2319

150%

2854

2778

2704

2631

2557

2481

2416

2332

2259

2188

200%

2692

2624

2553

2482

2409

2338

2275

2194

2124

2057

HYDRATED LIME - DETERMINATION OF AVAILABLE CaO

The quality of lime supplied to factories is an important but often neglected factor in the clarification process. Apart from the economic aspect, the use of substandard quality lime can introduce significant quantities of undesirable impurities into process.

Apparatus

Analytical balance Hot Plate

Conical flask 250 ml Filter paper. Whatman #1 or equivalent Pipette - 25 ml Burette - 50 ml

Reagents

Granulated sugar Phenol phthalein solution Sulphuric acid, 0.357N Procedure

1. Weight 5.0 g of the finely powdered lime sample. 2. Transfer to a 250 ml conical flask with 75—90 ml freshly boiled and cooled

distilled water. 3. Boil gently on a hot plate for three minutes, shaking with a rotary motion to break

up any lumps. 4. Cool the flask and contents to room temperature. 5. Dissolve 40 g of granulated white sugar in 40 ml of freshly boiled and cooled

distilled water. Add this to the flask with the lime. 6. Shake for 30 minutes with a rotary motion of the flask, keeping the lime in

suspension.

78

7. Complete to volume with freshly boiled and cooled distilled water and shake well. 8. Filter and discard the first 25-50 ml of filtrate. 9. Kpette 25 ml of the filtrate into a clean 250 ml conical flask. 10. Add 5 drops phenolphthalein solution and titrate with 0.375N sulphuric acid until

the pink colour just disappears.

Calculation

Available CaO% = ml of 0.375N sulphuric acid multiplied by 2.

Example

Titration reading = 31.6 ml Available CaO = 31.6 x 2 = 63.2%

79

MIXED JUICE - DETERMINATION OF SULPHATED ASH

Apparatus

Analytical balance Platinum dish (100-125 ml capacity) Hot Plate (or bunsen burner) Muffle furnace Desiccator Water bath Graduated cylinder (50 ml capacity)

Reagents

Concentrated sulphuric acid in a dropping bottle. Paraffin liquid.

Procedure

1. Heat dish to redness in oven or over a bunsen burner. 2. Cool in desiccator and weigh 3. Transfer 50 ml of filtrated juice to the dish and weigh. 4. Add 5 drops of concentrated sulphuric acid and mix by gently rocking the dish. 5. Heat on a water bath and evaporate to the consistency of final molasses. 6. Heat on a hot plate (bunsen burner) until completely charred. Start hot plate

on low heat and gradually increase heat to prevent spattering of the sample. If there is any tendency of the mixture to foam, add a few drops of liquid paraffin. This operation must be watched and cannot be hurried or the material will swell and overflow.

7. Transfer to the furnace and heat at 550° for 4 hours. 8. Cool first in air then in a desiccator and weigh to constant weight. Generally,

heating at 800°C for a further 30 minutes will be sufficient to arrive at a condition of constant weight.

Calculation

Weight of dish + juice = 99.527 g Weight of dish = 45.585 g Weight of juice = 53.942 g Weight of dish + ash = 45.994 g Weight of ash = .409 g %sulphatedash = 0.409 x 100

53.942

0.76%

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MIXED JUICE - DETERMINATION OF % EXTRANEOUS MATTER

Apparatus

1 litre measuring cylinder

Reagents

Procedure

1. Place a 1000 ml of mixed juice in a 1000 ml cylinder. 2. Allow to settle for 2 hours and read off the percentage of sediment in the bottom

of the cylinder. - 50 ml - 5% — good clarification. 6 0 - 150 ml 6 - 12% Fair More than 120 ml - 12% clarification problems

These results are for an average factory. The percentage sedimentation may be slightly different for your factory juice. Carry out the procedure on juice of known quality in your laboratory and use the results as your reference standards.

MIXED JUICE - DETERMINATION OF PHOSPHATE

Phosphate analyses are usually made to determine the clarification characteristics of juices.

Apparatus

Nessler tubes and Lovibond Comparator with a disc No. 3/51 covering the range 10-400 of phosphate. OR Colorimeter Volumetric (graduated) flasked - 50 ml, 100 ml. Pipettes - 10 ml, 5 ml graduated Timer Beaker Watch glass

Reagents

Ammonium molybdate reagent Ascorbic acid powder IN Sulphuric Acid Standard phosphate solution containing 25 ppm.

81

Procedure - Prepare 10 ppm phosphate solution as follows:-

1. Pipette 10 ml standard phosphate solution into a 100 ml graduated flask and make up to mark with distilled water - THIS SOLUTION NOW CONTAINS 10 ppm PHOSPHATE.

2. Pipette 25 ml of this solution into a beaker and add 15 ml distilled water and 4 ml Ammonium molybdate reagent and mix thoroughly.

3. Add 0.1 gm Ascorbic acid, cover the beaker with a watch glass and heat to boiling point for one minute. A BLUE COLOUR WILL NOW DEVELOP.

4. Cool the contents rapidly and transfer to a 50 ml volumetric flask. Wash beaker with distilled water and transfer washings to flask. Make up to 50 ml with distilled water and transfer washings to flask. Make up to 50 ml with distilled water.

5. Prepare a blank by Procedure 2-4 substituting water for phosphate solution in procedure 2. i.e. 40 mls water, 4 mls Ammonium molybdate etc.

6. Prepare Juice sample as follows: -A. Pipette 5 ml juice into a 200 ml flask. If sample is alkaline neutralise with IN

sulphuric acid. B. Dilute to 200 ml with distilled water. C. Proceed as in 2-4 above, substituting juice for phosphate solution in pro­

cedure 2. 7. A. Read 10 ppm phosphate standard and sample on instrument, (colorimeter,

640-740, set at zero with blank). OR

B. Compare standard and sample in Comparator/Nessler tubes.

Calculation

A. Reading of 10 ppm standard phosphate = 0.45 Reading of sample 0.36 .'. ppm phosphate in original juice sample = 0.36 x 10 x 200 = 320ppm.

0.45 5 = 320 ppm

B. Multiply ppm concentration obtained by 40.

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MIXED JUICE - DETERMINATION OF % MUD VOLUME OF LIMED AND HEATED JUICE

Apparatus

Hotwater bath Boiling Tube 10 ins x 1 in. Hot plate Centimetre (or inch) rule Alarm Clock (or Interval Timer)

Reagents

Procedure

1. Ensure that water in bath is at boiling point. Adjust with rheostat control if available.

2. Heat random sample of hot limed juice to boiling on a hot plate. 3. Fill boiling tube with sample of hot limed juice, and measure height of liquid in the

boiling tube = Hcm (ins). 4. Insert boiling tube in water bath, ensuring that level of water in bath is higher than

that of the hot limed juice. Set alarm clock to go off after one hour. 5. After one hour measure height of mud in the boiling tube = h cm (ins). 6. Calculate % mud volume of the limed and heated juice as follows:

Calculations

Height of liquid in boiling tube = H cms (ins). Height of mud in boiling tube = h cms (ins). % mud volume of limed and heated juice = h x 100

H

SUGAR - DETERMINATION IN EFFLUENTS

Appreciable amounts of sugar may be lost from a factory, carried away by entrain-ment and pass undetected in the large volume of water used in condensers etc., and which continually leave the plant. All such effluents e.g. condensates, condenser tail pipe water, should therefore be tested regularly and at short intervals.

Tests should be made on fresh or recently obtained samples only, as sugar content of samples several hours old will be greatly reduced due to bacterial decomposition.

A. Qualitative Test

Apparatus

Test tube - approx. 100 mm. Burette

Reagents

Alpha Naphthol solution Concentrated sulphuric acid.

83

Procedure

1. Make certain that all glassware and sample containers are free from any trace of sugar.

2. Cool a portion of the sample to room temperature. 3. Rinse a 100 mm test tube with a portion of the sample and half fill the tube

with the sample. 4. Add 5 drops of alpha - naphthol solution to the test tube and mix

thoroughly. 5. Hold the test tube in an inclined position with the tip of the burette contain­

ing concentrated sulphuric acid, touching the tube.

Allow about 2 ml of acid to run into the tube so that it flows to the bottom forming a distinct layer. Hold the tube upright - do not mix contents.

7. A lilac or purple ring at the interception of the two layers indicates sugar. If no purple or lilac ring appears after 15 seconds, the test is reported negative. The test is very sensitive and 100 ppm of sucrose gives a black ring due to a charing of the sugar by the acid.

8. A positive test for sugar should be checked by running a blank test with distilled water to ensure that the alpha naphthol has not been contaminated with sugar.

B. Quantitative Test

Apparatus

Pyrex Test tubes, approximately 150 x 20 mm, Comparator such as Lovibond or

similar

Reagents

Alpha naphthol — concentrated sulphuric acid — reagent.

Procedure 1. Pour 2.5 ml of sample * into a glass stoppered test tube. Pipette 5 ml of

sulphuric acid reagent down the side of the tube. 2. Stopper tube and mix gently by inverting two or three times, holding stopper

firmly in position. ** 3. Allow mixture to stand for exactly ten minutes with the stopper removed. 4. Replace the stopper and match with colour standards. 5. Read off amount of sugar in ppm in the indicator recess.

* Concentrations of more than 100 ppm may be determined by dilution. ** Considerable heat is evolved on addition of the acid solution and the stopper

should be removed each time the tube has been inverted.

Hold the tube away from the face when inverting the tube and always handle the acid with great caution.

84

CHAPTER VII

BOILER WATER TREATMENT

In order to ensure proper protection and efficiency of their boilers every factory should have some kind of boiler water treatment. Depending on the quality of the feed water, varying levels of sophistication in treatment methods will be required. Where an abundance of hot, clean condensate is available the minimum of treatment is required.

It must be noted however, that it is pointless going into any kind of treatment system without first ensuring that sugar contamination is eliminated. Further, without con­scientious and dedicated personnel, any treatment method is likely to be unsuccessful.

The main objective of boiler water treatment is to control the chemical condition of the boiler water so as to prevent the problems associated with scaling, corrosion and carryover. Possible problems include costly damage to boiler and auxiliary equipment, loss of efficiency and injury to personnel.

Scaling

Hard adherent scale is deposited in boiler tubes when water of varying degrees of hardness is fed to a boiler. This scale consists mainly of insoluble salts of calcium and magnesium. Other scale-forming compounds are sugar, silica, oil and undissolved solids.

To prevent scaling pure water should be fed to the boiler. Condensate which is readily available in a sugar factory approximates to this if it is kept free of sugar contamination. Any make-up water should be treated preferably in a lime (lime-soda can also be used) Softener and then brought to a maximum of about 5 ppm CaC03 hardness (preferably 3.0 ppm) in a zeolite or resin softener.

For further protection, phosphate treatment should be undertaken inside the boiler. This treatment is safe and adequate for the ordinary sugar factory. To ensure that all residual hardness is removed as phosphate sludge, boiler pH must be 10.5-11.5 or a minimum hydroxide alkalinity of 170-330 and residual phosphate 20-50 ppm. Adequate alkalinity is obtained by increasing the injection rate of caustic soda (rather than soda ash unless unavailable). Phosphate control is by injection of a solution of poly-phosphate solid sold under various trade names and containing various sludge con­ditioners.

The rate of feed of chemicals should be determined by analysing the boiler water alkalinity and phosphate level. Boiler water hardness analyses are unnecessary if feed hardness is properly monitored.

Corrosion

Corrosion takes place in the presence of acids (perhaps due to sugar), oxygen, carbon dioxide and other corrosive gases in solution. Acid attack is prevented if pH is kept within the range required for phosphate treatment or at least above 7. This means that sugar contamination should be avoided

85

Dissolved gases may be removed by heating the feed water as hot as possible and further heating in a deareator. Here steam is used to drive out gases from a spray of feed-water. To remove all traces of oxygen an oxygen scavenger, usually sodium sulphite (under various trade names) is fed into the feed line, after the deareator (see Fig. 7/1). Note also that piping, feed heaters and economizers should be protected.

In low pH water, high levels of chloride is dangerous. In most sugar factories chloride levels are less than the maximum (half the operational alkalinity).

For proper corrosion control the need to prevent sugar contamination cannot be overemphasized. Further control is achieved by feeding a solution of sodium sulphite and maintaining sulphite residuals in the range 30—60 ppm.

Carryover

Carryover is entrained boiler water carried in steam whether to superheaters or to process. Water carried over causes erratic conditions in superheaters and mechanical problems in turbines. But worse, solids carried over with entrained water can scale or block superheater tubes or destroy turbine blades. Carryover is caused by foaming or priming.

Priming is a surging of the boiler water into steam outlets and is due to some physical condition, such as load fluctuations. Foaming is the formation of stable bubbles through­out the boiler water.

Because of possible high alkalinity or high dissolved or suspended solids, or the presence of oil, strong, stable steam bubbles are formed. This causes expansion of the boiler drum contents which surge over into steam outlets.

Foaming is minimised by internal treatment with various sludge conditioners and anti-foaming agents. These may be mixed with treatment chemicals. However, carryover is best prevented by operating below a maximum alkalinity of about 350 ppm for 0—300 psi boilers and maximum dissolved solids of 3000 micromhos (2250 ppm). By blowing down intermittently there should be no build up of sludge to dangerous proportions. Continuous blowdown is controlled to give the required dissolved solids.

Pretreatment

The setting up of a pretreatment plant is a job for experts. There are different types of such plants depending upon the type of water to be treated and the purity of the water required. Fig. 7/2 shows a typical pretreatment plant for a sugar factory. The water source may be well or river. Where there is colour or odour due to organic matter, an activated carbon filter should be used, otherwise sand or anthracite may be employed.

The typical plant described by Fig. 7/2 is a cold lime softener followed by a cation softener unit. In the lime softener temporary hardness is removed as magnesium hydroxide and calcium carbonate by lime according to the following reactions.

MgSC-4 + Ca(OH)2 = Mg(OH)2 + CaS04

Mg(HC03)2 + 2Ca(OH)2 = Mg(OH)2 + 2CaC03 + 2H20

MgCI2 + Ca(OH)2 = Mg(OH)2 + CaCI2

Ca(HC03)2 + Ca(OH)2 = 2CaCC>3 + 2H20

86

Fig. 7/1. Sugar Factory Water Cycle

Natural and generated calcium chloride must then be removed by the cation exchange of softeners. If sodium carbonate is included with the lime (or lime-soda) softener, then calcium chloride is removed as follows:-

CaCl2 + Na2C03 = CaC03 + 2NaCl

Water leaving this unit will have hardness in the region of 40-120 ppm (CaC03) and alkalinity of 40-100 ppm (CaCC>3).

Alkalinity Test

1. Measure 100 ml of Filter Effluent in a dish. 2. Add 3 drops phenolphthalein (lime treatment should be enough to

colour, if not increase lime pumping). 3. Titrate M/25 Hydrochloric acid until pink colour just appears. 4. Record the burette reading. This is P. 5. Without disturbing the burette add 3—5 drops of Bromocresol Green -

indicator to the dish and continue the titration to the end point. 6. Record the reading. This is M.

The above measures all alkalinity i.e. carbonate, bicarbonate and hydroxide, ing relationships exist between P and M alkalinities as measured above.

Hydroxide (OH) Carbonate Bicarbonate P&M Alkalinity (C03) (HC03)

The liming rate is controlled by monitoring 2P — M and controlling in the 0.0 — 0.6 range.

Filter

The turbidity (cloudiness) of water leaving the lime softener should be kept at a minimum. This is done by using the proper amount of flocculant in this unit and not overfeeding the plant.

If this is maintained, cleaning of filter by backwashing may be done every other day. If not, they must be backwashed more frequently. In any case, they should not be allow­ed to stand in a dirty condition.

give a pink

Methyl red

89

Softeners

Softeners should be thoroughly backwashed with salt. Provision should be made that backwashing, regeneration and rinsing be done with partially softened water. Backwash water should be controlled at a maximum to prevent loss of resin, the level of which should be checked regularly. Loss in softener capacity occurs commonly due to:-

1. Too high hardness from lime softener (under or overtiming). 2. Poor regeneration. 3. Fouling by carryover from filter.

These units should be regenerated as soon as they indicate maximum hardness and should not be exposed to very hard water for a long time. They should not be allowed to stand in the. hard condition for long periods and the vessels should be kept full of water.

Internal Treatment

Boiler water is better dealt with by one of the many consulting firms in the field. These firms are able to supply treating chemicals mixed in the right proportions and with various sludge conditioners and anti-foaming agents. They also supply testing equipment and reagents. In deciding on the firm to employ, their experience is a major consideration.

Equipment

For phosphate and caustic pumping the following is required for each boiler:-1. 50 gal. tank of stainless steel or plastic. 2. Injection pump of about 2 gal/hr. 3. Mixer with stainless steel shaft.

If all boilers have the same feed source, then only one tank of approximately 200 gal. and a pump of about 4 gal/hr. is required for sulphite feed to all boilers.

A Simple Control Method

Phosphate, nitrates and caustic soda should be mixed in the same feeder using hot condensate for easy solution. Sulphite should be fed from a separate tank using cold water with the rninimum of mixing for solution. Feeding of all chemicals should be continuous and through a non-return valve. Giemicals should be introduced through a perforated pipe along the bottom of the boiler drum. It is better to employ a constant pumping rate and vary the concentration of chemicals. Set pumps to empty tank in 24 hours.

Concentration of chemicals required are determined simply on the basis of analyses of boiler water. After about six hours of operation, the analyses are repeated to determine the direction of change of chemical levels. Further additions or dilutions are then made to feeders. Small changes should be affected and within a short time control within the recommenced limits may be attained.

90

Recommended limits For Boiler Water Control

Sample Variable Control Range How Controlled

pH

Hardness Sugar B reading (OH - alkalinity) Phosphate Sulphite Conductivity Nitrate (if riveted boilers) Chloride

8.8-9.1

5 ppm(max) Nil 8.5 - 16.5 ml M/25 acid 20-40 ppm 30-60 ppm 3000 microho 5 x B reading

.5 x alkalinity

Pretreatment if make-up is used. Pretreatment Dump if present Caustic addition

Phosphate injection Sulphite injection Blowdown Nitrate injection

Increase alkalinity

Continuous blowdown has an effect upon all residual levels. Therefore this should be maintained at the minimum requirement for proper conductivity levels and chemicals should then be fed as required. Intermittent blowdown should not be more than twice per 8 hour shift to maintain proper desludging of the bioler.

Boiler Water Analysis

For basic boiler water treatment analyses of boiler and boiler feed water should be made at least once per day but preferably twice per day for good control. Tests should be made at, e.g. 7.00 a.m. and repeated at about 2.00 p.m.

Sampling

It is important that sampling be done properly. For hot boiler feed and all boiler waters, a water cooler should be used. This may consist of a stainless steel coil cooled in a bath of raw water. Boiler water samples should be collected from gauge glass or continuous blowdown line.

A clean plastic bottle, rinsed with sample should be filled and tightly stoppered. Sample should run for ten minutes before collecting.

In order to minimise oxygen contamination and so reduce'sulphite levels in sample, analysis for sulphite should be don-?, first and as soon as possible after collection.

METHODS OF ANALYSIS

Sulphite

Reagents - Starch Solution - 6 gm Potato Starch per litre + .5 gm NaHC03 Potassium Iodide - 0.18 M (30/gm/l). Potassium Iodate - .0026 M (0.5660 gm + 0.5 gm NaHC03/l) Hydrochloric Acid - 1 : 3 (250 ml cone. Acid + 750 ml H2O)

91

Feedwater

Boiler Water

Procedure 1. Into 250 ml flask measure 2 ml starch 2. Add 5 ml jHCl 3. Add 5 ml Potassium Iodide 4. Add 100 ml cool sample 5. Titrate Potassium Iodate with stirring to the first permanent blue colour,

ppm Sulphite = (ml Kl03 - 0.1) x 10

Alkalinity The B reading gives a measure of available hydroxide alkalinity required for corrosion

protection and phosphate sludging.

Reagents — Hydrochloric Acid — M/25 (3.3 ml of 12 M acid made up to one litre) Neutral Barium Chloride - 130 gm BaCl2 2H20 in one litre)

1. Measure 100 ml of sample into dish or flask. 2. Add 10 ml Barium Chloride solution and stir. 3. Add 3-4 drops phenolphthalein and stir. 4. Titrate until just colourless.

Alkalinity ppm CaC03 = Vol. acid x 20. B Reading = Vol. acid.

Hardness of Feedwater Reagents - EDTA 0.01 m (3.7224 gm/1)

Buffer solution pH 10 Erichrome black indicator

1. Measure 100 ml of clear sample 2. Add 5 drops of pH 10 buffer and stir. 3. Add 3 drops of fresh indicator solution or enough powder to give a dark red colour.

If sample has zero hardness a blue colour will immediately appear. 4. Titrate EDTA to blue end point

Hardness, ppm CaC03 = Volume EDTA x 10

Notes 1. For feedwater with suspended solids, 100 ml is acidified with 1 ml 2M HC1.

Then 5 ml pH 10 buffer is added. The titration is then carried out as above. 2. For hard water sample, (above 100 ppm) use 50 ml sample and two dropper-

Ms (2 riu) buffer. Hardness = Vol. EDTA x 20. 3. For boiler water, sample should be filtered before test.

Solids in Boiler Water

The dissolved solids content of a water sample is directly proportional to and may be measured by its electrical conductivity. This may be done using a conductivity meter sold by any water treatment firm. The instrument will have a range of about 0-10,000 micromhos equivalent to about 0—8500 ppm dissolved solids in raw water. The dissolved solids may be evaluated from the conductivity reading (see note 1.) but this is unnecessary since the value of conductivity may also be used for control.

92

The ratio of dissolved solids to suspended non-ionic matter is fiarly constant so that the value of conductivity may also be used to regulate blowdown rates. These rates are set to maintain the conductivity values of boiler water within a certain control range. Reagents - Phenolphthalein indicator

Gallic Acid powder

1. Plug in and switch on conductivity meter. 2. Rinse conductivity cell and cylinder with sample. 3. Pour 100 ml sample into cylinder. 4. Add 4 drops phenolphthalein. There should be a pink colour if boiler water is at

proper alkalinity. 5. If there is a pink colour add pinches of gallic acid and stir until colour disappears.

(Excess gallic acid is not harmful). 6. Move conductivity cell up and down in sample to remove air bubbles then take

reading at balance point. 7. After use rinse cell and store in distilled water.

Notes 1 1. Type of Water

Boiler Water

Raw, Softened & Cooling Water

Condensate

Conductivity Range Micromhos/cm

4000 - 10000 1000—4000 1000 1000 400 - 1000 400 0 - 5 0

(After Gas Correction)

To Convert to ppm Multiply by

0.82 0.75 0.68 0.85 0.80 0.75 0.65

2. A standard conductivity solution should be used to occasionally check conductivity meter.

Nitrates

The presence of excess nitrate in boiler water ensures a protective ferric oxide scale on boiler tube surfaces, protecting the boiler against caustic embrittlement. Such em-brittlement occurs where high concentrations of caustic soda may build up e.g. such as rivets, leaks, expanded ends or poor welds.

Usually however, where there are no riveted seams in the boilers, continuous nitrate protection is not practised. Nitrate levels are maintained by feeding sodium nitrate to the boiler to a residual level of about five times B reading i.e. 42 ppm - 82 ppm NO3 (68—132 ppm as CaC03). This should give the minimum nitrate here .4 x hydroxide alkalinity.

Nitrate tests are complicated and the only suitable routine analysis is a colorimetric method. A colour comparator may be obtained from a water treatment consulting firm.

93

Chlorides

High chlorides may cause pitting under rust deposits caused by oxygen. Chlorides are dangerous at low pH. Attack of sodium chloride can be prevented by maintaining the ratio of alkalinity to chloride of 2:1 (chloride concentration expressed as ppm CaCO3). Reagents - Silver Nitrate -0 .14 M (2.4 gm/1)

Potassium Chromate 10% (100 gm/1). Phenolphthalein indicator Sulphuric Acid M/4 (13.8 ml conc, acid in 1 litre) or 0.5 M Nitric Acid Hydrogen Peroxide 30% (containing max. 0.001% chloride) Distilled Water must be chloride-free.

1. Filter boiler water sample if turbid. 2. Measure size sample depending on estimated chloride level as follows:-

Estimated Chloride ppm CI Sample Size (ml) Multiplying Factor

0 - 125 100 5 125 - 250 50 10 250 - 500 25 20 500 - 1250 10 50 Above 1250 5 100

Samples less than 100 ml should be made up to 100 ml with chloride-free distilled water.

3. (a) If boiler water is highly coloured add 5 ml Hydrogen peroxide, cool before proceeding,

(b) If there is no colour but sulphite is present, add 1 ml Hydrogen peroxide. No boiling is necessary.

4. Add a few drops phenolphthalein and with stirring add sulphuric acid until pink colour just disappears.

5. Add 1 dropperful (1 ml) potassium chromate. 6. Titrate with silver nitrate solution until a drop produces a light orange colour which

persists after vigorous stirring. 7. Chloride concentration - ml titration x Factor.

The factor used depends on sample size. See table step 1.

Notes 1. To determine whether or not distilled water is chloride-free add 1 drop

sulphuric acid and a few drops of silver nitrate to 100 ml distilled water. Sample will become milky after a few minutes if chloride is present.

2. If sample is acid (which it should not be for boiler waler) it must be neutral­ized by obtaining a pink colour with phenolphthalein by adding sodium hydroxide dropwise. Then add just enough sulphuric acid to just discharge the pink colour.

94

Phosphates

Analysis for phosphate is a colorimetric determination. A simple colour comparator with prepared reagents may be obtained from a water treatment consulting firm. Other­wise the determination may be done using any brand of photo electric colorimeter. A red filter i.e. wavelength region of 640-700 millimicrons should be used. The method consists of first determining a standardization curve for phosphate using known solutions. The sample, corrected by a blank test is determined from the standard curve. Reagents - Ammonium Molybdate solution 1004M (See note 3)

Stannous Chloride (See chapter on Reagents) Trisodium Phosphate, 200 ppm (0.3453 gm/1 Na3P04).

1. Prepare 100 ml standard phosphate solutions by diluting quantities of 200 ppm phosphate solution as follows:-

ppmP04

mls of 200 ppm Sol

0

0

10

5

20

10

50

25

80

40

100

50

2. Pipette 5 ml of each in 50 ml flasks. 3. Add 10 ml of molybdate solution to each and shake well. 4. Add 5 ml Stannous Chloride and mix well by shaking. 5. Five minutes later measure the intensity of each solution with colourimeter set to

read zero absorbance with 0 ppm solution and using the red filter. 6. Plot calibration curve of intensity/ppm PO4. 7. To determine boiler water phosphate sample is filtered and 5 ml measured. 8. 5 ml of distilled water is also measured in a separate container for a blank

determination. 9. A colour is developed in the sample and the blank as for standards. 10. The instrument is zeroed and the blank and sample read. 11. The sample reading is corrected by the blank reading and determined from the

calibration curve.

Notes 1. For higher phosphate concentrations, the sample may be diluted and the

result multiplied by the dilution factor or a calibration curve of wider range of phosphate concentration employed.

2. Colour intensity increases with time so all readings should be done within 10 minutes of colour development.

3. Dissolve 5 gms of Ammonium molybdate (NH4) 6MO7O244H2O in 700 ml distilled water, add 40 ml cone. H2SO4. When cooled make up to 1 1.

Standby Protection Corrosion protection of a boiler in the standby condition is as important but more

difficult than in the operating condition. Much deterioration has occurred inadvertently during this period even in cases where good water treatment is practiced.

95

The two conditions to be considered are intermittent standby where the boiler should be ready to start at short notice, and a prolonged standby e.g. the out of crop period.

Intermittent Standby Sometime before the boiler is stopped the sulphite level should be raised to about

100 ppm and the alkalinity to about 250-400 ppm i.e. a B reading of about 12.5-20 ml. If this causes a carryover, some means must be found to charge the bioler after shut-down with hot feed into which caustic soda and sodium sulphite has been fed to give the above levels.

Periodic checks should be made on the water and any deterioration should be improv­ed by injecting these chemicals into the suction of a pump used to circulate the boiler water. Prolonged Standby

There are two methods.

1. The boiler is completely filled, superheaters included, and kept filled with good quality water as described above. A tank on top of the boiler drum kept full will ensure this even if there are leaks.

2. The boiler is kept completely dry. Here superheaters are drained, and where this is not possible warm air is blown through the superheater tubes initially. Then a series of electrical or gas heaters should be equally spaced in the furnace at the lower end of the superheater bank. To ensure that no moisture is formed on the surfaces, trays of desiccants such as quicklime or silica gel are placed inside the boiler drums. These must be checked periodically. Alternatively a series of hot bulbs may be used instead of the chemical and the boiler is: shut up so that all surfaces remain dry.

Sugar Contamination Sugar and reducing sugars entering the 'boiler in contaminated feedwater breakdown

to form corrosive acids. These rapidly reduce boiler alkalinity resulting in acid attack on boiler metal and loss of phosphate protection. To avoid or to reduce the probability of sugar contamination :-1. . Condensate should be used from Nos. 1 and 2 evaporators, No. 2 juice heater (if

heated by No. 1 vapor), vacuum pans and pre-evaporator heaters. 2. If the above stream includes other than exhaust steam condensate is used, the level

in N.o. 1 vessel should be controlled and closely watched. 3. Samples should be analysed for sugar hourly or monitored by an instrument such

as a conductivity meter. 4. Condensate streams should flow to a special tank before entering boiler feed

stream. This tank should be monitored and dumped when sugar is detected.

Action To be Taken in the Event of Sugar Contamination 1. Check alkalinity while increasing caustic pumping rate to boiler. 2. Slowdown rapidly and frequently to avoid too high alkalinity build-up and to

remove carbon and to change the' boiler water. 3. Phosphate will have to be increased also. 4. If it is possible to shut the boiler down, do so and completely flush.

96

CHAPTER VIII

STANDARD SOLUTIONS AND REAGENTS

Chemicals used for the preparation of reagents should be of the highest quality. They should be protected against contamination from dust, moisture, other foreign matter, should be kept in a cool, dry place and be properly labelled.

Acetic Acid

Use - Determination of final molasses purity. Glacial acetic acid, CH3COOH.

Alcohol

Use — Preparation of slurry, saturated mecurtc chloride solution and special analyses. Ethyl alcohol 95%, C2H5OH Methyl alcohol CH3OH Isopropyl alcohol, 100% CH3CHOHCH3

Alpha — Naphthol solution

Use — Test reagent for sugar in drain waters and condensates.

Preparation

(1) Dissolve 20 gm of analytical reagent grade Alpha - Naphthol in 95% alcohol and dilute to 100 ml.

(2) Store the solution in an amber-coloured bottle.

The dropping bottle used for the reagent should also be amber-coloured to prevent excessive exposure to light.

A fresh solution should be prepared about once per month. The compound looses sensitivity after being opened and exposed to the air.

Alumina Cream (Hydrate of Alumina)

Use — Clarification of juice for Pol determination.

97

Use b) — Colorimetric determination of silica in boiler water.

Preparation

(1) Dissolve 100 gm of ammonium molybdate in 700 ml of distilled water. (2) Add 250 ml of ION sulphuric acid solution slowly while stirring and cool. (3) Add one (1) drop of concentrated nitric acid, HNO3, make up to one (1)

litre with distilled water and store.

Asbestos Fiber

Use — To filter Fehling's solutions.

Preparation

(1) Digest a quantity of asbestos on a steam bath with 1:2 hydrochloric acid solution for 48 hours.

(2) Pour onto a Buchner funnel and wash it with four (4) portions of hot distilled water.

(3) Transfer the asbestos back to the beaker and digest with 5% sodium hydrox­ide solution for 48 hours.

(4) Pour onto the Buchner funnel and wash with four portions of distilled water. (5) Again, transfer the asbestos back to the beaker, add a quantity of 1:2 nitric

acid solution and 3 or 4 gm of potassium permanganate crystals, stir well and digest for 36 hours on the steam bath.

(6) Add enough sodium sulfite to reduce all the permanganate, indicated by a change from brown to colourless.

(7) Again transfer to a Buchner funnel and wash with 4 or 5 portions of hot distilled water to remove all soluble material. Continue until the asbestos is free from excess water and dry at 100°C. Store in a wide-mouthed jar.

Buffer Solutions A buffer solution of pH 7.0 should be used to check the pH meter. However, at times

it is necessary to check the meter over a wide range. Therefore instructions are given for the preparation of three different pH ranges.

pH4.65

(1) Weigh on an analytical balance 13.607 gm of sodium acetate (NaC2

H302.3H20). (2) Transfer to a 1000 ml volumetric flask. Add about 500 ml of distilled water

and mix until dissolved.

98

Ammonium Molybdate solution

Use - Colorimetric determination of phosphates in boiler water and juice.

Preparation

(3) Measure 5.7 ml of glacial acetic acid into the flask and complete to volume with distilled water.

(4) Mix thoroughly. Add 5 drops of chloroform as a preservative and store in a glass-stoppered or polyethylene bottle. The solution will keep indefinitely.

Alternatively Potassium Hydrogen Phthalate (0.05M) may be used.

(1) Weigh on an analytical balance 10.21 gm of dry Patassium Hydrogen Phtha­late (A.R.).

(2) Dissolve in approximately 500 ml of freshly distilled water.

(3) Make up to 1000 ml mark of volumetric flask with distilled water.

pH 7.0 (1) Weigh separately on an analytical balance 3.631 gm of mono-basic potassium

phosphate, KH2PO4, and 5.684 gm of anhydrous dibasic sodium phosphate, Na2HP04. l

(2) Transfer both salts to a 1000 ml volumetric flask, add 500 ml of distilled water and mix until dissolved.

(3) Make up to the 1000 ml mark, mix well and add 5 drops of chloroform as a preservative and store in a glass-stoppered or polyethylene bottle.

NOTE - This buffer is rated at pH 6.85 at 25°C.

Temperature °C

20 25 30 35 40 45

KH Phthalate (0.05 M)

4.00 4.01 4.01 4.02 4.03 4.04

KH2P04

(0.025M) Na2HP04

__(0.025M)

6.88 6.86 6.85 6.84 6.84 6.83

Borax

___O01M

9.22 9.18 9.14 9.10 9.07 9.04

Ca(OH)2

saturated at 25°C_

12.63 12.45 12.30 12.14 11.99 11.84

99

Cleaning Solutions

(a) Chromic - Sulphuric acid solution Use

Cleaning of laboratory glassware

Caustic Potash Solution

Use - Rue gas analyses. Tube B of Orsat Gas Apparatus.

Preparation

Make up a concentrated solution of caustic potash (KOH) of approximately 60° Brix.

Cuprous Chloride Solution

Use — Flue gas analyses. Tube D of Orsat Gas Apparatus

Preparation

(1) Weigh out 26 gms of cuprous chloride. (2) Dissolve in 200 ml of concentrated hydrochloric acid. (3) Add 120 mis of distilled water and store.

Copper turnings or foil must be added to the storage bottle. It is also impor­tant to add copper turnings to the absorption pipette of the Orsat Gas Appatatus.

Pyrogallic Acid/Caustic Potash Solution

Use — Flue gas analyses. Tube C of the Orsat Gas Apparatus.

Preparation

Make a solution of 5 parts of pyrogallic acid in 50 parts of hot water and 100 parts of caustic potash solution of approximately 50° Brix.

(1) Dissolve 80 gm of potassium dichromate in 300 ml of water heating until the crystals are dissolved.

(2) Cool and add slowly while stirring 460 ml of concentrated sulphuric acid.

CAUTION - Avoid contact of solution with skin or clothing.

(b) Phosphate - oleate solution

Preparation

(1) Add 60 gm of trisodium phosphate and 30 gm of sodium oleate to 500 ml of distilled water.

(2) Warm the solution to 70°C and allow the glass to soak in the solution for 15 minutes.

Erichrome Black T Indicator Solution

Use - Determination of hardness of water.

100

Preparation

(1) Add 1 ml of N sodium carbonate to 30 ml of distilled water in a 100 ml volumetric flask.

(2) Then add 1.0 gm of Erichrome Black T and mix. (3) Make to 100 ml with isopropyl alcohol, mix and store in an amber-coloured

bottle.

Fehling's Solution

Use — For the determination of reducing substances.

Preparation

A. (1) Weigh on an analytical balance 34.639 gm of copper sulphate (CuSO4.5H2O). (2) Transfer to a 500 ml volumetric flask and add distilled water, mix until

dissolved and make up to mark. (3) Allow the solution to stand for two days and filter if necessary through

prepared asbestos.

(1) Weigh on an analytical balance 173.00 gm of Rochelle salt (sodium potassium tartrate) and 50.00 gm of sodium hydroxide.

(2) Transfer to a 500 ml volumetric flask and add distilled water, mix until dissolved and make up to mark.

(3) The solution is allowed to stand for two days and filter through prepared asbestos.

The solutions are mixed in equal proportions by volume, immediately before use.

Formaldehyde solution

Use — Preparative for juice samples except those for reducing substances determina­tion.

Reagent grade, 36-38% formaldehyde HCHO.

Hardness Buffer Solution

Use — Determination of calcium and magnesium in water.

Preparation

Solution 1 Dissolve 40.0 gm of sodium tetraborate (Na2B4O7.10H20) in approximately 800 ml distilled water.

Solution 2 (1) Dissolve 10.0 gm of sodium hydroxide NaOH and 5.0 gm of sodium sulphide

(Na2S) in 100 ml of distilled water. (2) Cool, mix the two solutions in a 1000 ml volumetric flask and make to mark

with distilled water. Store in an amber-coloured bottle and keep well-stoppered when not in use.

101

Hardness Reagent

Preparation

(1) Dissolve 4.0 gm of disodium ethylene diamine tetra-acetate (Na2CjoHi4 OgN2.2H20) in about 800 ml distilled water.

(2) Add 0.86 gm of sodium hydroxide, NaOH, and make up to 1000 ml in a volumetric flask with distilled water.

Store in an amber-coloured bottle.

Hydrochloric Acid

Hydrochloric acid 36-38% HCl(conc). Specific, gravity 1.18-1.19.

Hydrochloric Acid for Inversion (Jackson & GiDis method) Chemically pure hydrochloric acid is diluted to a specific gravity of 1.1029 (24.85°

Brix).

Lead Acetate, Basic (Home's Dry Lead)

Use — For clarification of sugar products for analysis.

Preparation

This may be prepared by evaporating to dryness the concentrated solution of basic lead acetate, prepared as described below. The resulting mass is ground to a fine powder in a laboratory mortar.

It should contain 72.8% lead, so that the salt corresponds to a composition of 3Pb (C2H302) .2PbO.

Lead Acetate solution, Basic (Wet Lead)

Use — For clarification of raw sugar for Pol analysis.

Preparation 1

(1) Weigh out 4.30 gm of neutral lead acetate and 130 gm of litharge. (2) Transfer both chemicals to a litre of distilled water and boil the solution for

30 minutes. (3) Allow to cool and settle. (4) Dilute the supernatant liquid to a specific gravity of 1.25 (543° Brix) with

freshly boiled distilled water.

Preparation 2

(1) Weigh 360 gm of basic lead acetate, Home's dry lead into 1500 ml beaker. (2) Add 1000 ml of distilled water. Stir well and boil gently for 30 minutes. (3) Allow to cool and settle until clear. (4) Decant the clear liquid and dilute to an indicated 21.9% refractometer solids

with distilled water.

Lead Acetate solution, Neutral

Use - Clarifying sugar products for reducing substances analysis.

102

Preparation

100 gm lead acetate, Pb (C2H3O2)2, are dissolved in distilled water and made up to 1000 ml to give a 10% solution.

Mercuric Chloride

Use — Juice sample preservative

Preparation

A saturated solution of mercuric chloride in alcohol is prepared.

Methylene Blue, Solution

Use - Indicator for reducing substances analysis.

Preparation

(1) Weigh 1.0 gm of methylene blue and transfer to a 100 ml volumetric flask. (2) Fill the 100 ml volumetric flask to the half-way mark with distilled water and

dissolve. Make to volume with distilled water and mix well.

Potassium Iodide - Iodate solution, 0.0I25N

Use —Determiantion of sulphite in boiler water.

Preparation

(1) Weigh 0.45 gm of Potassium iodate (KIO3) on an analytical balance. (2) Transfer to a 1000 ml volumetric flask and add 100 ml of distilled water,

mix well until dissolved. (3) Add 4.35 gm of Potassium iodide (KI) and 0.31 gm of sodium bicarbonate

(NaHC03). Mix until dissolved.

Complete to volume with distilled water.

Potassium Oxalate, De-leading solution

100 gm of Potassium oxalate are dissolved and make to 1000 ml with distilled water to give a 10% solution.

Phenolphthalein

Use — pH indicator

Preparation

(1) Weigh 1.0 gm of phenolphthalein powder (2) Transfer to a 200 ml volumetric flask, add 100 ml of isopropyl alcohol

and dissolve. (3) Add cautiously, drop by drop, 0.1N NaOH until a faint pink colour appears

then add one (1) drop of 0.1N sulphuric acid, H2SO4. Complete to volume with distilled water.

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INDICATOR TABLE

Name pH Range Colour Change

Methyl Orange 3.1 - 4.4 Red to Orange Bromocresol Green 3.8 — 5.4 Yellow to Blue Methyl Red 4.2 - 6.2 Red to Yellow Bromothymol Blue 6.0 - 7.6 Yellow to Blue Phenolphthalein 8.2 - 10.0 Colourless to Red

N Sodium Carbonate

Use - To make up Erichome Black T Indicator Solution

Preparation

(1) Weigh 53 gm of solium carbonate, special anhydrous. (2) Transfer to a 1000 ml volumetric flask and fill about half with distilled

water and dissolve. (3) Complete to volume with distilled water and mix.

Sodium Hydroxide Solutions

1. 5% solution approximately.

Use - Preparation of asbestos fibre.

Preparation

(1) Counter-balance a 1500 ml beaker on the dilution balance. (2) Weigh 50 gm of sodium hydroxide, pellets, NaOH. (3) Add 950 gm of distilled water. (4) Stir until dissolved and cool to room temperature and store.

2. N Solution

Use — Determination of acidity in acid cleaning solutions

Preparation (1) Counter-balance a 100 ml beaker on the analytical balance. (2) Weigh 42.5 gm of sodium hydroxide, pellets, NaOH. (3) Transfer to a 1000 ml volumetric flask and fill to about half with distilled

water. Mix until dissolved. (4) Cool to room temperature and make to mark with distilled water. Mix

thoroughly and store.

3. O.1N Solution

Use — Titration of acids

Preparation

(1) Weigh 4.3 gm of sodium hydroxide pellets (2) Transfer to a 1000 ml volumetric flask and fill to about half with distilled

water.

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(3) Mix until dissolved, cool and make to volume with distilled water. Mix thoroughly and store.

Sulphuric Acid

Reagent - Sulphuric acid, 98% H2SO4 (concentrated), specific gravity 1.84; molecu­lar weight 98.08.

Sulphuric acid solutions

1. ION solution

Use — Preparation of ammonium molybdate solutions.

Preparation

(1) Fill a 1000 ml volumetric flask to about half with distilled water. Place in a bath of cold running water and slowly add 280 ml sulphuric acid while mixing with a rotary motion.

(2) Cool to room temperature, make to mark with distilled water and store.

2. N. Solution

Preparation

(1) Fill a volumetric flask to about half with distilled water and add from a burette 29 ml of sulphuric acid.

(2) Mix with a rotary motion and cool to room temperature. (3) Complete to volume with distilled water.

3. O.IN solution

Preparation

Prepare O.l N solution from the above N solution. Pipette 100 ml of N sulphuric acid solution into a 1000 ml volumetric flask and make up to 1000 ml with distilled water.

4. 0.357N solution

Use — Determination of available CaO in lime

Preparation

(1) Transfer 10.2 ml of sulphuric acid from a burette to a 1000 ml volumetric flask containing about 500 ml of distilled water.

(2) Mix and store.

5. 0.02 N solution (N/50)

Use — Determination of alkalinity in boiler water.

Preparation

Pipette 20 ml of N sulphuric acid solution into a 1000 ml volumetric flask con­taining 500 ml of distilled water. Make to mark with distilled water.

105

CHAPTER IX

CALCULATIONS AND FORMULAE

Introduction

The calculations contained in this chapter are included with a view to standardization of methods. The formulae do not, of course, include all the calculations which the chem­ist required to make in his capacity as statistician. Other calculations will be found elsewhere in this manual.

Control data are needed for routine factory control as well as the basis for cane payment. Factory control data is recorded on a daily, weekly, monthly and crop basis.

Control data are derived from quantities determined by weighing (sometimes by measurement) along with figures determined by direct analyses. Quantities to be deter­mined by weighing and by direct analyses are listed in this chapter.

Decimals

Rules for Recording and Rounding Off.

1. Measurements must be stated with one and only one uncertain digit, e.g. a dish weighs 24.2357 gms. The last digit representing tenths of a milligram is uncertain, but we are definite that the dish weighs between 24.2355 and 24.2357 gms.

2. When rounding off digits in any calculation, increase the last remaining (retained) digit by one (1) of the digits being dropped which is greater than five (5). When the number to be discarded is exactly five the last remaining digit shall remain unaltered if it is an even number, but„if it is an odd number one (1) shall be added.

3. In addition and subtraction retain only the number of digits beyond the decimal point as is present in the figure having the least number of decimal places.

106

4. In multiplication and division retain in each number and in the answer derived only that number of digits which will introduce no greater uncertainty than already exists in the number with fewest significant digits.

Formulae

Data to be directly determined:-

A: By weight

1. Weight of cane 2. Weight of Imbibition water 3. Weight of Mixed Juice (Net) 4. Weight of Filter cake 5. Weight of Final Molasses 6. Weight of Sugar

B: By analyses

7. Brix % Mixed Juice 8. Pol (or sucrose) % Mixed Juice 9. Moisture % Bagasse

10. Pol (or sucrose) % Bagasse 11. Brix % last Expressed Juice 12. Pol (or sucrose) % last Expressed Juice 13. Pol (or sucrose) % first Expressed Juice 14. Pol (or sucrose) % Sugar 15. Moisture % Sugar 16. Pol % Final Molasses 17. Brix % Final Molasses 18. Clarified juice pH 19. Brix % Clarified juice 20. Pol (or sucrose) % Clarified juice 21. Brix % Syrup 22. Pol (or sucrose) % Syrup 23. Syrup pH.

C: Brix and Fibre % Bagasse

1. Brix % Bagasse

Pol (or sucrose) % Bagasse x Brix % last Exp. Juice or (10)x(11) Pol (or sucrose) % last Exp. Juice (12)

2. Fibre % Bagasse 100 - Brix bagasse - Moisture % bagasse or 100 - L(9) + (25)

3.

107

108

I l l

112

113

Copps factor = 97(sugar purity - molasses purity) Sugar purity (97 — molasses purity)

= 97(97.69 - 32.00)

97.69 (97 - 32.00) = 1.04528

Mixed Juice Filter Juice B. Molasses A. Molasses

100.00 50.00 60.00 75.00

16.50 14.00 82.50 81.00

13.70 10.50 40.43 48.60

83.00 75.00 49.00 60.00

13.70 5.25

24.26 36.45

79.66

.9181

.8667

.5837

.7334

12.58 4.55

14.16 26.73_

58.02

CHAPTER X

TIME ACCOUNT

1- Gross available time for a run is the total time from the start to the end of the run 2. Net available time is the gross available time minus a maximum of 12 hours for

weekend cleaning. 3. All Stoppages must be classified into factory stoppage and non-factory stoppages. 4. Factory stoppages must be classified in the following: -

(a) Mechanical (b) Electrical (c) Knife Chokes (including cane carrier — see appendix). (d) Mill Chokes (e) Steam (f) Process Stops (g) Labour (h) Extraneous Matter (i) Excessive Cleaning Time

5. Non-factory stoppages must be classified in the following:-

(a) Public Holidays (b) Out of Cane supply, due to:-

(1) Labour (2) Weather (3) Transport (4) Farmers short deliveries (5) Estate short deliveries (6) Mechanical

APPENDIX

DEFINITION OF STOPS

1. All stoppages are to be recorded after a 3 minute time lapse from the time the cane stops entering the crusher or first mill to the time the cane starts entering the crusher or first mill.

2. Stoppages must be recorded in hours to the second decimal place also the percen­tage of the gross available time as per Appendix IV.

3. Run reports must be submitted on a weekly basis (168 hours gross) except the first week of crop which may be a part week.

116

Gross Available Time Gross available time in any week will be 168 hours or the actual time in any part of a week, e.g. Start or end of crop. Net Available Time The net available time is the gross available time (168 hours) minus standardized cleaning time (12 hours) or gross available time minus actual cleaning time if less than 12 hours. Weekend Cleaning This has been established at a maximum of 12 hours, any period below 12 hours will increase the net available time and reduce the time for weekend cleaning for the week in question.

However, any genuine cleaning stops over 12 hours, the excess must be charged as a Factory Stop under the heading "Excessive Cleaning". Definition of Factory Stoppages (a) Mechanical

Down time charged to this account should be for any mechanical breakdown that causes the mill to stop grinding. In addition, any time that the mill is not grinding cane after the standardized 12 hour stops for cleaning at weekends due to mechanical repairs being in process.

(b) Electrical Down time charged to this account should be for any electrical breakdown that causes the mill to stop grinding. In addition, any time that the mill is not grinding cane after the standardized 12 hour stops for cleaning at weekends due to electrical repairs being in process.

(c) Knife Chokes Down time charged to this account should be for any choke at the knives or cane carriers that causes the mill to stop grinding cane. If, however, the choke is caused by tramp iron, low steam, etc., the stop should be charged to that account (i.e. Extraneous matter).

(d) Mill Chokes Down time charged to this account should be for any choke at the mill that causes the mill to stop grinding cane. If, however, the choke is caused by tramp iron, low steam etc., the stop should be charged to that account (i.e. Extraneous matter).

(e) Steam Down time charged to this account should be for any time that the mill cannot grind cane due to insufficient boiler steam pressure. This should also include time lost due to raising steam after the allotted time for cleaning at weekends or other stops.

(f) Process Stops Lost time charged to this account should be for any time that the mill cannot grind cane due to a fault in the processing of the juice, syrups, molasses or

117

sugar, and there is no mechanical, electrical or steam fault. A good example would be Pan Floor congestion caused by slow curing massecuite due to false grain. On the other hand a Pan Floor congestion caused by a centrifu­gal being out for mechanical repairs will be charged to mechanical, or, lack of steam for boiling to low steam.

(g) Labour Down time charged to this account should for any time that themill cannot grind cane due to labour dispute in the factory and go-slows. Should the mill have to stop grinding due to a worker sleeping or absent from his station the lost time should also be charged to this account.

(h) Extraneous Matter Downtime charged to this account should be for any time that the mill can­not grind cane due to extraneous matter entering the Factory. This would also include cleaning sand from the boilers on shift, the charge would not be low steam. Also removing chains etc. from carries and mills.

(i) Excessive Cleaning Time This account should be used only when the standardized cleaning time allowed for cleaning boiler furnaces, heaters, evaporators and pans is exceeded.

Definition of Non-factory Stoppers (a) Public Holidays

Time charged to this account should be for any time that the mill cannot grind cane due to any recognised Public Holidays.

(b) Out of Cane Time charged to this account should be for any time that the factory cannot grind cane due to the following and should be broken down into the follow­ing categories:-(1) Labour

This would be due to any labour dispute and go-slows in the field. (2) Weather

Time charged to this account would be any time lost due to excessive rain and should also include time that is allowed for the fields to dry out after the Fain.

(3) Transport Any time that the factory cannot grind cane due to lack of transport to convey the cane to the factory, including breakdown of haulage tractors.

(4) Farmers deliveries Time lost in the factory due to insufficient cane supplied by the farmers.

(5) Estate Deliveries Time lost in the factory due to insufficient cane supplied by the Estate.

118

(6) Mechanical Time lost in the factory due to the breakdown of cane loaders or mechanical harvesters.

Items (4) and (5) would necessitate a firm quota system being in force for

the controlled ordering of cane supply by the Factories.

CHAPTER XI

METRICATION

The passing of the weights and measures Act (1976) makes the metric system legal in Jamaica. The metrication Board under the Ministry of Industry and Commerce is respon­sible for executing the changeover.

The change to the metric system is a worldwide trend which Jamaica must follow in order to continue trade even with countries which are traditional users of the Imperial System. The system used is a refinement of the original metric system and is called the International System of Units (SI).

This chapter will not deal with how the system will be introduced into the sugar or any other industry. This is the function of the Metrication Board working in coordination with a particular organization. However, the SI Unit as used in the sugar industry will be discussed together with some basic ideas governing the application of the system.

S.I. UNITS

The International System of Units is intended as a basis for worldwide standardiza­tion of measurement units. The system consists of base units, supplementary units and derived units. There are seven well-defined base units which by convention are dimension-ally independent. They are related to the variables of length, mass, time, temperature, electric current, luminous intensity and amount of substance. We shall be dealing here with the four former units.

120

Magnitude of Units

Different magnitudes of the S.I. Units are obtained by using decimal multiples or submultiples of base units. These are named by prefixes identifying the powers of ten to which the units are raised. Some of the more common ones are as follows:-

Thus, 12 millimeters - 12 mm The prefixes are used to avoid large numbers, and non-significant digits and powers of ten notation. For example,

15,600 mm = 15.6 m 18.5 x 103 gm = 18.5 kg 0.000 m = 6 m m

Some of the prefixes are not in very common use e.g. hecto, deka, deci and centi (except cm) and should be avoided.

APPLICATION

Rules for Writing

The writing of unit symbols and names is governed by international agreement and come under the following rules:-

1. Unit symbols should always be printed in Roman (upright) type; 2. Unit symbols are unaltered in the plural; 3. Unit symbols are not followed by a period except when used at the end of a

121

122

CONVERSION FACTORS

Conversion factors hesre are multiplying factors for converting measurements in one system to a corresponding measurement in the other system. In converting from one system to the next, accuracy should be preserved. Consequently, rules should be followed in applying them. However, the usual practice in the sugar industry is to do all multi­plications and divisions to at least three decimal places and then to round off to two places.

This is not accurate introducing apparently significant digits and greater accuracy than can be achieved and does not take into account the precision of the measuring devices. This is acceptable within the industry. But there are definite rules of conversion as set out by the Bureau of Standards, which should be universally applied.

The following rules of conversion should be practised within the industry:

1. Conversions should first be ma de and then rounding off is done.

Neither the measured quantity nor the conversion factor should be rounded;

e.g. 23.6 ft. converted to metres = 23.6 ft. x 0.3048 m = 7.193 28 m = 7.19 m (rounded)

2. When the first digit to be discarded in rounding is less than 5, the last digit in the final number should not be changed; e.g. 36.9348 rounded to 2 decimal places is 36.93 .

3. When the first digit to be discarded is greater than 5, or if it is a 5 followed by a number greater than 0, the last remaining digit should be increased by 1. Thus 496.3251 = 496.33 (correct to 2 decimal places)

4. When the first digit discarded is exactly five followed by a zero, the last digit retained should be increased by 1 if it is an odd number, but remain unadjusted if it is an even number.

e.g. 53.9350 = 53.94 (Correct to 2 decimal places)

53.9250 = 53.92 (Correct to 2 decimal plgces).

SUGAR FACTORY OPERATIONS

The cost of conversion to the metric system would vary with different factories. There are some equipment which may have to be replaced with ones made in metric dimensions. Scale heads may be replaced or recalibrated. In some cases measurements may have to be made in the British System and converted to the metric system. In any case metric units will be standard for all factories.

The following table lists the common variables in a sugar factory and field opera­tions with the usual British units, the conversion factors with the corresponding S.I. unit.

123

124

CHAPTER XII

LABORATORY MANAGEMENT AND FIRST AID

Care of Samplers & Containers

All sugar products are susceptible to rapid deterioration due to bacterial activity. All sample containers should therefore be thoroughly cleaned and frequently sterilised. Sample jars should be washed with hot water after use and thoroughly dried. Metal containers should also be washed and steamed frequently.

Care of Optical Instruments

Optical instruments (polarimeters, refractometers, microscopes) are delicate and expensive. If treated properly they will last for a very long time; if not, they will deterior­ate very rapidly giving erroneous results.

These instruments should be set up in a position free from dampness and corrosive fumes, jarring and vibration. Where it is not practicable to set up an instrument away from the mill vibration it should be mounted on a suitable anti-vibration table.

The instrument should be examined and cleaned regularly, especially troughs and splash glasses of polarimeters and prisms of refractometers. Never use a sharp instrument to place material on prisms and always wipe with soft material.

Balances should be kept clean and handled with care. Weights should never be held with the fingers. Objects should never be weighed hot; but allowed to cool preferably in a desiccator. Instruments should be kept under a cover when not in continuous use.

Use and Care of pH Metre and Electrodes

All glass electrodes should be immersed in distilled water for at least twenty-four hours prior to use. When not in use, it should be stored in distilled water of buffer solu­tion, as repeated wetting and drying impairs the action of the glass membrane.

Check the electrodes at least once a day with standard buffer solution. The instrument should be protected from splashes of sample or water and kept dry.

Safety and First Aid

Accidents are caused - they do not happen. Persons are always directly or indirectly responsible for accidents.

The chemical laboratory is potentially a hazardous place, but if the necessary safety precautions are followed it can be as safe as any other place. The three areas of greatest danger are from:

a) Chemicals b) Fires and Explosion c) Glassware

REMEMBER ACCIDENTS ARE PAINFUL, EXPENSIVE AND CAN BE LETHAL. AVOID THEM !!!

125

Spillage and Residuals

Mop up chemicals or water which may be spilled on the floor AT ONCE. A slip or stumble may be more serious in a chemical laboratory than elsewhere, as the person may not only be carrying a chemical but also a glass container. Use of Pipette

When using a pipette be careful that no liquid is drawn into the mouth. Do not use a pipette to withdraw corrosive or poisonous liquids. Use an aspirator bulb, a burette or for less accurate work — a measuring cylinder. Bottles and Other Containers

All containers should be clearly and correctly labelled. After consulting your supervi­sor, discard chemicals in containers which are unlabelled. This is a safety precaution: NEVER INSERT ANYTHING INTO A REAGENT STOCK BOTTLE, POUR MATERIAL BACK INTO A STOCK BOTTLE OR EXCHANGE STOPPERS ON BOTTLES, OTHER­WISE CONTAMINATION MAY RESULT.

Always use a funnel to pour liquids from a larger mouthed container into a smaller one. Always replace the stopper immediately after pouring to avoid mix up and possible contamination. When pouring always hold the bottle in such a way that the label is upwards. This prevents damage to the label by the dripping back of liquid. Solutions and Acids

Never add water to a concentrated acid, rather cautiously add acid to the water with constant stirring in small amounts at a time.

FIRST AID

First Aid is an immediate and temporary action given to a victim of an accident or sudden illness to prevent or reduce suffering and possible loss of life until proper medical aid is available. General Hints

1. Always know what to look for; what to do and how to do it. 2. Prevent and/or reduce bleeding or further injury. 3. Check and maintain breathing and apply artificial respiration if necessary. 4. Avoid panic. 5. Develop confidence. 6. Summon help.

Burns and Scalds

Burns are the result of dry heat. Scalds are produced by a hot liquid or steam. Action of chemicals is referred to as a 'Chemical burn'. Heat Burns and Scalds (Minor)

When the burn is confined to a part of the limb such as one hand, some lessening of pain may be achieved by immersing the injured area in cold water. Cover with dry sterile gauze or cloth.

126

(Serious) - If clothing is on fire, smother flames with a blanket or lab coat. Remove or cut away clothing over burned area, but do not attempt to pull away clothing which is stuck. Cover burned area with sterile or clean dressing and bandage or fasten securely.

In case of burns covering a large area of the body, it is sufficient to cover with a clean sheet or towel. If the patient is thirsty, he may be allowed to drink small amounts of clear fluid such as water. Seek medical aid promptly. Never treat large burns with tannic acid, oil or antiseptic ointment. These remedies greatly complicate the surgical treatment of the burned area and have only slight value in reducing pain.

Chemical Burns

Acid Burns — Wash copiously with quantities of tap water, then 1% sodium bicarbonate solution and again with water.

Alkali burns — Wash with copious quantities of tap water and then 1% acetic acid and

more tap water.

Chemical in the Eye

To save sight first aid is vital. Flush eyes with large quantities of water. Seek medical aid.

Foreign Bodies in the Eye NEVER rub the eye, blow the nose and tears will flow to help flush out particles. If

this fails use eye bath or tap water to flush out particles. Glass in the eye is very serious and no first aid beyond covering the eye with sterile lint and bandaging firmly to prevent movement should be done. Seek medical aid immediately.

Wounds

Minor cuts - Remove dirt or glass, and wash under tap. Apply clean sterile dressing.

Severe Bleeding is stopped in the following manner:

a) If on the arm, leg, hand or foot and blood is scarlet and flowing intermittently, a torniquet is applied 4 ins. below the armpit, or 4 ins below the groin.

b) If the blood is dark and purplish, the tomiquet is applied below the wound. A piece of rubber tubing will make a good tomiquet.

CAUTION: Under no circumstances should the torniquet be held tight for longer than 15 minutes at a time. It is loosened and the blood allowed to flow for a few seconds, then re-tightened. The tomiquet is loosened but not removed as soon as the blood clots.

If bleeding is copious and the wound is in a position where a torniquet cannot be used a pad of sterile gauze soaked in acriflavine is placed in the wound and a bandage applied.

If the cut is slight and bleeding is copious, all foreign matter is removed and the cut is cleaned with acriflavine solution (1 in 1,000) and a dressing of this material applied.

POISONING

(a) Strong Acids Mouth or lips may be stained. Vomiting is not induced. Magnesium oxide, milk of

magnesia or lime water is given immediately and is repeated at short intervals and the

127

mouth is washed with one of the above-mentioned materials. Carbonates are not to be given, but milk or white of egg. The patient is placed in a reclining position to combat collapse, and blankets etc. are applied.

(b) Alkalis Mouth or lips may be stained. Vomiting is NOT induced. A 5% solution of acetic

acid or vinegar is given until alkali appears to be neutralized. Milk or white of egg is given and the above efforts made to combat collapse.

(c) Copper Salts If a fairly large amount is swallowed, give an emetic and after vomiting give white

of egg or a suspension of charcoal in water. Avoid milk or oils.

(d) Lead Compounds Vomiting is induced by stirring one teaspoonful of powdered mustard in suf­

ficient water to make a creamy paste or warm salt water may be used, 4 gm. Sodium Thiosulphate in 450 ml water or 10% Magnesium Sulphate is administered. Combat collapse.

(e) Mercuric Chloride One teaspoonful Sodium Thiosulphate in 500 ml water is given by mouth or a

glass of milk with four tablespoonsful charcoal. Vomiting is induced and the treatment is repeated. Soothing drinks of milk and raw eggs are given. (0 Silver Nitrate

Two tablespoonsful of table salt (Sodium Chloride) in 50 mls of water is given. Vomiting is induced.

GAS POISONING

(a) Corrosive gases The patient is carried into fresh air, artificial respiration is applied, if necessary.

The patient, if conscious, is allowed to inhale an antidote (dilute acetic acid for ammonia, dilute ammonia for bromine, chlorine, hydrochloric acid or nitric acid fumes). Combat collapse.

(b) Carbon Monoxide, Hydrogen Sulphide and Nitrous fumes The patient is removed to the fresh air, artificial respiration is applied and oxygen

given. Combat collapse. After apparent recovery and restoration of breathing the patient is not allowed under any circumstances to walk or sit up until seen by a doctor.

SHOCK

Any injury may produce shock and may be serious enough to prove fatal. The symp­toms are paleness, moist skin and trembling. In case of minor injury, the patient must lie down and rest, a warm glucose drink may be given. Keep the patient lying down as long as possible. If vomiting develops keep the patient on his side and incline his head. Keep head lower than the rest of the body.

In cases of more serious injury, allow the patient to lie on his side. Try to get him cooler by loosening clothing.

128

If the patient is unconscious, do not give him fluids. As a general rule do not give the patient alcohol especially if abdominal injury is suspected. Electric Shock

Firstly, switch off the current if possible or remove patient from the electrical contact by using a hooked dry stick or insulated material, e.g. dry towel or rubber tire or other rubber article.

Artificial respiration should then be given. The patient is kept warm.

FAINTING

When a person feels faint get his head down quickly. If the patient is sitting, lower his head between his knees or lay him down with his head lower than the feet. If unconscious, place in the prone or semiprone position. Loosen clothing at neck, chest and waist. See that there is plenty of fresh air. On recovery, which is usually rapid, gradually raise the patient and give sips of water or other beverage. If unconsciousness continues for a longer time, suspect some cause more serious than fainting and summon medical help.

ARTIFICIAL RESPIRATION

It has been shown conclusively that this is the only really efficient method.

When a casualty has stopped breathing it is more important to get oxygen (air) into the lungs than to try to discover exactly why he has stopped breathing, although the cause is often obvious from the surroundings, etc. e.g. electrocution, coal-gas poisoning. One indication that breathing has stopped is discoloration of the lips, nails, ears and cheeks.

The air breathed out contains more than enough oxygen to supply the need of the casualty.

(1) If possible, lie casualty on back with head a little higher than feet.

(2) Tilt the casualty's head back and lift the jaw. This should move the tongue away from the back of the throat, the most common cause of respiratory obstruction.

129

One of three things may now happen:

(i) Normal breathing may begin at once and consciousness may quickly return. The casualty's colour becomes pink again. He should be watched carefully in case he stops breathing again.

(ii) Normal breathing may begin but consciousness not return. Place in the coma position and keep the airway clear (see Aftercare, page 69). The victim may have bumped his head.

(iii) Breathing may return but be noisy which means that the airway is not fully clear. All noisy breathing is obstructed breathing (but there is no noise when the airway is completely blocked). Try to clear the airway fully; there may be some fluid in the throat.

(3) If breathing does not restart clean the mouth and throat of any obvious block­age by fluid, vomit, weed or other obstruction.

(4) If after clearing the throat there is still no sign of breathing:

130

(ii) Take a deep breath;

(i) Check that the head is still tilted back;

(iii) Close his mouth and blow firmly but gently into his nose OR Pinch his nose and blow firmly but gendy into his mouth. As you do this the chest will rise.

(iv) Give four quick breaths and then continue with one breath every five seconds — 12 times a minute.

(vi) If the chest does not rise and fall you are not making a proper seal over his nose or mouth, or the airway is still obstructed and needs to be cleared again.

(vii) If the casualty is a baby make a seal with your mouth over his mouth and nose and breathe into him gently with a puff of the cheeks. Repeat this about 20-25 times a minute. Do not blow violently into a baby's lungs.

(viii) If the airway is clear it will not be long before the "pink" colour replaces the "blue" look. As consciousness returns the victim will start to breathe on his own; this is the time to stop resuscitation. Continue to hold his chin up and so keep his airway clear.

THE FIRST AID CABINET The contents of a typical First Aid cabinet should be kept as simply as possible and

grouped in a logical sequence. The labels should be clear and all ambiguity should be avoided.

The First Aid Cabinet

Internal Medicines Aspirin Antacid

ii) Dressings Band Aid Sterile Gauze Bandages (gauze) Lint Strapping Cotton Wool

131

iii) Equipment Medicine droppers Scissors Tweezers Eye cup Forceps Torniquet Cotton wool and cotton buds Thermometer (clinical) Safety pins Teaspoon and glass First Aid Manual

iv) External Medicines Mercurochrome Disinfectant Hydrogen Peroxide - 3% Petroleum jelly Sodium bicarbonate — 5% Alcohol - 95% Eye lotion Olive oil Smelling salts Acriflavine

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APPENDIX I TABLE INDEX

Appendix I: A chart of sampling and analyses frequencies 133

Appendix II: The determination of the polarization of Export sugars 134

Appendix III: The activity of Invertase concentrate 136

Appendix IV: (a) Time Account sheet 137

(b) Time Account sheet 138

Table I: Refactometer temperature correction 27.5°C 139

Table II: Polarization from Polariscope Reading (without dilution) and Degree Brix (corrected to 27.5°C) 140

Table III: The Winter Availability Factor for 'Pol' in products of different purities 154

Table IV: The conversion of tons Commercial Sugar to tons 96° Sugar at 1.03% moisture 155

Table V: Invert Sugar Table - Milligrams of Reducing Sugars required to reduce 5 ml Fehling's Solution (Lane and Eynon method) 157

Table VI: Invert Sugar Table - Milligrams of Reducing Sugars required to reduce 10 ml and 25 ml Fehling's Solution (Lane and Eynon method) 158

Table VII: Brix, Specific Gravity, weight per unit volume at

27.5°C 159

Table VIII: Temperature Conversions — Fahrenheit and Centigrade 165

Table IX: Sodium hydroxide Solutions Brix 5 169

Table X: Lime Slurry Concentrations at 15°C (59°F) 169

Table XI: Crystal Content of Massecuites (%Brix) 170

Table XII: Coversion Factors 171 TableXlll: Clerget Divisors 175

Table XIV: Temperature correction for Basic Clerget Divisor 176

Table XV: Atomic Tables (based on isotopeC 12) 177

133

APPENDIX II

THE DETERMINATION OF THE POLARISATION OF EXPORT SUGARS

Wet Lead defecation method:

This method should be used for all export sugars.

26.00 grams of the sample are rinsed with water into a 100 ml. flask. When the sugar has been dissolved by swirling the flask, the volume is brought up to 90 ml. and the solution clarified by the addition of 0.5 to 0.7 ml. of basic lead acetate solution (see page 29), after which the procedure outlined on page 20 is followed.

(a) Polarisation by Saccharimeter:

The value to be finally reported is derived as in the following example:-Reading

Tube filled with distilled water (mean of five readings) .... 0.07° (1) Instrument trough empty (mean of five readings) 0.05° (2) Sugar Solution (mean of five readings) 96.64° (3) :.mean reading of solutions corrected for instrument error (3—1) .. .. 96.57° (4) Temperature of observations 28°C. Quartz plate value certified at 20°C 95.97° (5) Quartz plate temperature correction* corresponding to 28°C +0.24° (6) :. Quartz plate value adjusted to 28°C. (5)+(6) 96.21° (7) Instrument reading of Quartz Plate (mean of five readings) 95.92° (8) Quartz plate readings (8) corrected for instrument error (8) — (2) .. .. 95.87° (9) Correction to bring (4) to 20°C. (7) - (9) +0.34° (10) :. Polarisation corrected to 20°C. and reported as such (4) + (10) .. .. 96.91 °

(b) Polarisation by Polarimeter:

The simple optical train of the circle polarimeter ensures maintenance of adjustment and eliminates inaccuracies of scale calibration due to irregularities in the rotation of quartz wedges or fluctuations in temperature. Provided therefore that the instrument is properly adjusted, it is not necessary to check each polarisation with reference to a quartz wedge. Consequently, apart from any instrument error, the only significant correction necessary for temperature is that due to the influence of temperature on the optical rotation of the mixture of sucrose and the other sugars in raw sugars. These consi­derations explain the form of an empirical relationship due to C.A. Browne such that:

% error due to temperature = 0.0015 (P - 80)(t - 20) where P = the purity of the raw sugar and t is the temperature in °C. at which the polarisation is carried out. Lane and Eynon (in a private communication) recommended that for raw sugars, a correction of + 0.02 per °C. above 20°C. is adequate in view of the usual invert sugar content of raw sugars. * Taken from the temperature correction table supplied with each quartz control

plate.

134

The value to be reported is therefore derived in the following manner-Reading

Tube filled with distilled water (mean of five readings) 0.004° (1) Sugar solution (mean of five readings) 96.816° (2) Sugar solution corrected for instrument error (2) —(1) 96.812° (3) Temperature of observations 28°C (4) Temperature correction corresponding to 28°C. (8 x 0.02) +0.160° (5) :. Polarisation corrected to 20°C. and reported as such (3) + (5) 96.972°

If the instrument is checked by means of a quartz plate, it should be borne in mind that the table of temperature corrections given with quartz plates is based upon -

st = St = S20 [1 + 0.0003 (t - 20) ]

and refers to the readings which sucrose solutions (reading the same as the quartz plate at 20°C.) would give if read in a saccharimeter at t° C For checking a polarimeter, what is required is the reading which the quartz plate would register in a polarimeter at t° C, and this is given by adding 0.0143 (t - 20). 20°C.

The polarimeter can also be checked by using the purest sucrose available, which should be not less pure than 99.98% pure sucrose. The sugar should be dried in a Spencer oven for 20 minutes at 110°C. and cooled in a desiccator before weighing.

NOTE: Whether a saccharimeter or polarimeter is used, the light must be filtered through an amber coloured filter which is equivalent to 30 mm, of a 3% potassium

bichromate solution.

135

APPENDIX III

THE ACTIVITY OF INVERTASE CONCENTRATE

NOTE: Invertase requires storage at 40°F. and frequent checking of its activity is

necessary.

Method:

Prepare the following solutions: (1) Dilute 1 ml. of the Invertase concentrate to 200 ml. with distilled water. (2) Dissolve 10 gm. of pure sucrose in distilled water and transfer to a graduated

100/110 ml. flask, acidify with two drops of glacial acetic acid and make to the 100 ml. graduation with distilled water.

Add 10 ml. of solution 1 to solution 2 and mix thoroughly; allow to stand for 60 minutes at room temperature (20°C). Make a portion of this solution alkaline to litmus paper by the addition of anhydrous sodium carbonate and polarise in a 200 mm. tube. If the diluted Invertase solution is of standard activity, a sugar solution polarising at 31.0° Pol would be given, without correct­ion for the volume increase from 100 to 110 ml., or for any optical activity of the Invertase. Invertase of this nature should give the following degree of inversion:

Calculation:

10 gm. Sucrose in 110 ml. has a Pol of 34.96°: when completely inverted the Pol should be - 11.22°, thus giving a drop in Pol of 34.96° + 11.22 = 46.18°, i.e. % drop caused by the correct activityof the invertase

is 100 x (34.96 - 31,00) = 8.58% 46.18

If, however, a Pol of 26.00° is obtained on the partially inverted sucrose in the determination, the

% drop in Pol = (34.96 - 26.00) x l00 = 19.40% 46.18

A activity of our Invertase = 19.40 = 2.26 8.58

Since 10 ml. of normal activity invertase solution as prepared above (or 5 ml. of the 1% solution), are required for inversion, then the volume of 2.26 activity invertase required is 4.42 ml.

136

APPENDIX IV (a)

137

APPENDIX IV (b)

138

139

TABLE II

POLARIZATION FROM POLARISCOPE READING (WITHOUT DILUTION) AND DEGREE BRIX

For use with Solutions prepared with Dry Subacetate of Lead and Brix Hydrometer standardised at 27.5°C. or Refractometer

140

141

142

TABLE II (Contd.)

TABLE NO. II (Contd.)

143

144

145

TABLE II (Contd)

Degree Brix 7.5 - 13.0

146

147

148

TABLE II (Contd.)

149

150

151

152

153

TABLE II (Contd.)

TABLE III

154

TABLE IV

155

TABLE VI

158

TABLE VII

BRIX, SPECIFIC GRAVITY, WEIGHT/UNIT VOLUME 27 1/2 °C

159

TABLE VII (Contd.)

161

162

TABLE VII (Contd.)

TABLE VII (Contd.)

163

TABLE VII (Contd.)

164

TABLE VIII

165

TABLE VIII (Contd.)

166

167

TABLE VIII (Contd.)

TABLE VIII (Contd.)

168

TABLE X LIME SLURRIES CONCENTRATIONS

(at l5°C, (59°F))

169

TABLE IX

SODIUM HYDROXIDE SOLUTIONS

BRIX %

TABLE XI

CRYSTAL CONTENT OF MASSECUITE (% BRIX)

To convert to Crystal Content % Volume multiply by °Brix

170

TABLE XII

CONVERSION FACTORS

171

TABLE XII Conversion Factors (Contd.)

Kilograms/meter lbs. ft. 0.67197

172

TABLE XII Conversion Factors (Contd.)

173

TABLE XII Conversion Factors (Contd.)

174

175

Sugars — For all sugars the value 132.63 at 20° C. may be adopted.

Molasses — For normal samples of molasses the value 131.88 at 20° C. may be adopted.

For other materials or other methods of inversion the divisor must be calculated from the specific data. All Clerget divisors must be corrected for temperature according to the table.

TABLE XIII - Clerget Divisors.

When analyses are conducted according to Jackson Gillis Method IV, the presently accepted formula for conversion of polariscope readings to sucrose concentration is:-

S = 100 ( P - P 1 ) 132.63 + 0.0794 (m - 13) - 0.53 (t -20)

where S = Sucrose per cent in sample P = direct reading calculated to basis of normal solution P1 = Invert reading calculated to basis of normal solution m = concentration of dissolved solids in g. per 100 ml. of solution as read in

polariscope t = temperature in °C.

The basic value of 132.63 applies to the Walker method of inversion (heat to 65° C, add acid, allow to cool). For inversion by the U.S. Customs method (add acid, immerse in 60° C. bath, stir for 3 min., hold 7 more min., cool quickly) the basic value is 132.56, whilst for inversion at room temperature (24 hr.) the value is 132.66.

For Invertase inversion the Clerget divisor is given by the formula -132.1 + 0.0833 (m - 13) - 0.53 (t - 20).

Using the Walker method of inversion some useful Clerget divisors, at 20° C, are: Juices — The divisor is related to the brix as follows:

TABLE XIII (a)

TABLE XIII(B)

Subtractive Temperature Corrections for Clerget Divisors.

176

TABLE XIV

TEMPERATURE CORRECTIONS FOR BASIC CLERGET DIVISOR (0.53t)

177

TABLE XV

INTERNATIONAL ATOMIC WEIGHTS, 1966

Published by the C.R.E. Handbook of Chemistiy and Physics

178

TABLE XV(Contd.)

NOTE: The above Atomic Weights are based on Isotope C12

179