Universiti Teknologi PETRONAS

CAB 2093 Process Safety and Loss Prevention

LABORATORY MANUAL

January 2007

Chemical Engineering Programme Universiti Teknologi PETRONAS

Bandar Seri Iskandar, 31750 Perak

TABLE OF CONTENTS

1. REPORT FORMAT . . . . . . . 3 2. SAFETY IN LABORATORY . . . . . . 4 3. EXPERIMENT 1: FLAME PROPAGATION AND STABILITY UNIT .. . 5 4. EXPERIMENT 2: FLASH POINT ANALYZER . . . . 9 5. EXPERIMENT 3: LOSS OF CONTAINMENT OF LIQUID . . 17 6. EXPERIMENT 4: LOSS OF CONTAINMENT OF GAS . . . 22 7. EXPERIMENT 5: BOMB CALORIMETER . . . . 27 8. EXPERIMENT 6: NOISE LEVEL ANALYSIS . . . . 32

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REPORT FORMAT The following table shows details of laboratory reports format that must be submitted by each group.

Item Description Cover Page Contains the UTP logo, the title of the experiment, the group

name/number, the names of the group members and student ID, the name of the demonstrator/technician in charge, the date of experiment and the date of submission.

Table of Content List down all the titles/content in the report. Objectives Highlights the main objectives of the experiment. Introductions Mentions about summary of theory, the fundamentals and

background of the experiment. Results Presents the results of the experiment. The results should be in

line with the objectives of the experiment. Discussions Discusses the experimental results. The discussion should relate

experimental findings with its associated theory. Conclusions and Recommendations

Should emphasize the main findings of the experiment. The conclusion should answer every aspect of the experimental objectives. Any weakness in the experiment or any proposal of methods to improve the experiment should be discussed.

References Contains the list of references made in the report. Appendices Contains the raw reading taken during the experiment, sample

calculations and any additional information.

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SAFETY IN THE LABORATORY (IMPORTANT – PLEASE READ CAREFULLY)

1. When working in the laboratory, the student must wear proper attire, i.e. fully covered low-heel shoes (sandals and slippers are not allowed) and buttoned-up laboratory coat. Students with long hair, or headscarves, must ensure that their hair is, or headscarves are, neatly tied up and/or tuck into their laboratory coats. Safety goggles are required when necessary.

2. Before entering the laboratory, the student should be aware of the safety equipment at

hand (e.g. fire extinguisher, safety eye wash, eye protector, safety shower) and their respective locations, functions and methods of use. The student should also be aware of the building’s exit locations.

3. The student is expected to behave in a proper and safe manner in the laboratory.

Avoid crowding. Horseplay, smoking, eating and drinking in the laboratory are strictly prohibited.

4. The student is advised to practice good housekeeping to ensure a dry, tidy and clutter-

free work area. The work area should be free from bottles, books, papers or anything that is not in use. Any chemical spill must immediately be wiped clean.

5. Be sure to clean and dry all apparatus after each laboratory session. All apparatus

must be returned to their original locations after use.

6. When handling chemicals, especially organic chemicals, are toxic and/or flammable. Avoid touching, tasting, swallowing, sniffing and/or inhaling the chemicals and/or their vapors. When using a pipette, the student should use a pipette filler or rubber bulb, and not stuck liquid into the pipette using his/her mouth.

7. The student should quickly and carefully wash his/her eyes of other parts of the body

with water should there be any chemical coming into contact with the eye or other parts of the body. Use the safety eyewash or safety shower if necessary.

8. Be wary of unlabelled containers. Do not use chemicals from unlabelled containers.

Furthermore, be careful to label all test tubes and bottles when in use.

9. Do not dispose waste chemicals into the sink or down the drain. Consult the demonstrator(s) or laboratory technician(s) on duty for proper disposal guidelines.

10. When using glassware, check for cracks on other defects. Do not use faulty glassware.

11. In the event of a fire in the laboratory, immediately inform the demonstrator(s) and/or

laboratory technician(s) on duty. Use the fire extinguisher to keep the fire from spreading. Evacuate the laboratory quickly and in an orderly manner if necessary. If any student’s clothes catch on fire, quickly roll the student over the floor and/or cover him/her with a safety blanket if available.

12. In the event of any accident, immediately notify the demonstrator(s) and/or laboratory

technician(s) on duty.

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Experiment 1: Flame Propagation and Stability Unit 1. Learning Objectives

To measure the flame speed in case of Air/Gas (Liquefied Petroleum Gas)

mixtures 2. Introduction: Modern industry demands the highest

possible efficiency in the utilization of all

types of fuel. To achieve this, fuel and air

must be mixed in the correct proportion

under stable conditions implying knowledge

of the combustion characteristics of the fuel

and the underlying aspects of fluid

mechanics. The Flame Propagation and

Stability Unit have been designed to

investigate the behavior characteristics of

flames in a quantitative and qualitative

manner. This bench top unit allows

supervised student operation and analysis

over a very wide range of air/fuel ratios and gaseous fuel types. The observations and

experiments that can be conducted include flame stability, measurement of the air/fuel

ratio, flame speed, arresting and quenching techniques as well as methods of

expanding stability limits.

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3. Apparatus:

Flame Propagation and Stability Unit (P.A Hilton Ltd.) consists of following components: No. Component Description Flame Speed System 1 Panel

Steel Control Panel, include: air flow meter (tube 14X), gas flow meter (tube 7X), mixture gas flow meter, air control valve, gas control valve and air blower switch

2 Air Tube to Mixing Block Black plastic tubing, connector from air flow meter to mixing block

3 Gas Tube to Mixing Block Clear plastic tubing, connector from gas flow meter to mixing block

4 Mixing/Burner Block Steel block for mixing air and gas 5 Burner Adaptors Two flame speed adaptors each complete

with flame traps. One adaptor fitted with an igniter plug.

6 Flame Speed Tube 25mm diameter x 5m long clear PVC tube. 7 Igniter

Consists of igniter box, igniter switch and igniter plug.

8 Lighter Hand held 9 Safety Valve Foot operated gas safety valve. 4. Theory A small blower provides primary air which is controlled by a valve and its flow rate measured by a variable area flowmeter. Slow burning gaseous fuel from cylinders or mains is controlled and measured in a similar manner. Both air and gas area separately introduced into a mixing block designed to accommodate a variety of mixing tubes. The speed at which a flame passes along a stationary column of gas/air mixture is an important part of the understanding of flame stability. A 5 meter length of 25 mm bore clear plastic tube is connected to the mixing block and a known mixture allowed to pass through. Both gas and air valves are closed simultaneously and the arrested mixture is ignited by means of a spark plug. The time for the flame to pass over a measured distance is easily recorded and the results are plotted.

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5. Experimental Procedure:

1. Switch on main switch. 2. Turn on gas supply to unit. 3. Open air control valve and observe that air flow is through to burner block. 4. Place foot on switch pad and open gas control valve. The gas flow rate may be

measured using either of the two flow meters. The long flow meter is used for natural gas while the shorter one is used for mixture of propane and butane. The flow meter calibration curves can be used to determine the flow rate of gas.

5. Ignite mixture at burner using the lighter. 6. When flame established, adjust controls for minimum air/fuel ratio such that

flame is bluish in color at the burner block. When ratio is set, wait approximately 5 seconds until flame is steady then close air and gas control valves completely. At the same time operate the ignition unit trigger and operate the stop watch to determine the time of flame travel between measured reference points on the plastic tube.

7. Mark start and end points on the plastic tube to determine the flame speed in between these two points.

8. Repeat the experiment by increasing the air flow rate and correspondingly adjusting the gas flow rate such that flame becomes bluish in color. Determine the flame speed.

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6. Observations: No. Indicated

Gas Flow (cm)

Gas Flow (m3/sec)

Indicated Air Flow

(cm)

Air Flow (m3/sec)

Time (sec)

Flame Speed (m/sec)

Air/Fuel Ratio

1 5 10 10 5 2 5 12 10 10 3 5 14 10 15 4 5 16 10 20 5 5 18 10 20 7. Results and Discussion:

1. Plot the results using flame speed (m/s) on x-axis and air/gas ratio on y-axis

for different gases and compare the results. 2. Discuss the importance of this experiment in context of its application in the

industrial system with special reference to different kind of burners installed in fuel furnaces.

8. Safety Precaution

1. Wear eye protection at all times. 2. Wear jeans or slacks, a long sleeved shirt, and sturdy shoes that give good

traction on possibly wet floors. 3. Guard against electrical hazards by making sure that all equipment is well

grounded using three-wire plugs and other means. 4. Handle with great care any solvents or other potentially volatile,

flammable, toxic, or otherwise dangerous chemicals. 5. Guard against falls, burns, cuts, and other physical hazards. Use heavy

gloves to open or close hot steam or condensate valves. 6. Think first of safety in any action you take. If not certain, ask the TA or

faculty member before you act.

9. References:

Daniel A.Crowl, Joseph F.Louvar “Chemical Process Safety” , Second Edition , Prentice Hall Inc, 2002.

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Experiment 2: Flash Point Analyzer

1. Learning Objectives

1.1 To determine the flash point of pure liquid components and their mixtures.

1.2 To determine the Lower Flammable Limit (LFL) using the flash point.

2. Introduction

The flash point of a liquid is the lowest temperature at which it gives off enough vapor to form an ignitable mixture with air. At the flash point the vapor will burn but only briefly; inadequate vapor is produced to maintain combustion. The flash point generally increases with increasing pressure. There are several different experimental methods used to determine flash points. Each method produces a somewhat different value. The two most commonly used methods are open cup and closed cup, depending on the physical configuration of the experimental equipment. The open-cup flash point is a few degrees higher than the closed-cup flash point. The fire point is the lowest temperature at which a vapor above a liquid will continue to burn once ignited; the fire point is higher than the flashpoint.

Cleveland Opened Cup Flash Point Tester Tag Closed Cup Flash Point Tester The term “ignitable mixture”, describes a concentration that is within the flammable range (between the Lower Flammable Limit [LFL] and the Upper Flammable Limit

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[UFL]), and thus, is capable of igniting and projecting a flame at and beyond the source of ignition. These upper and lower limits are reported as the percentages by volume of a particular material dispersed in air. If the vapor concentration is below the Lower Flammable Limit, it is “too lean” to propagate flame; if it is above the Upper Flammable Limit, it is “too rich”. Values for these limits are usually determined at atmospheric pressure. A decrease in pressure will lower the LFL and make the potential for ignition greater. The temperature at which the LFL is reached is also known as the Flash Point. Unless a material is highly volatile, an ignitable level will not be reached unless its vapors are confined in a storage vessel or mixing tank. Flammability is an important factor in the development of safe practices for handling and storage of liquid mixtures, and for the evaluation of the precise levels of risk associated with gaseous flammable mixtures. Depending on whether a mixture is in the liquid or gas phase, the properties of flash point or lower flammable limit are required.

Lower flammable limit:Minimum composition limit of a combustible vapor in air over which a flame can propagate.

Flash point: Minimum temperature at which the vapor over a liquid forms a flammable mixture when mixed with air.

Liquid

Vapor

Relationship between the properties of flash point (Tf) and the lower flammability limit (LFL) The relationship between the flash point and the lower flammable limit can be described mathematically by:

( )P

TPLFL f

sati

i = ………………..(1)

where P is the atmospheric pressure and ( )f

sati TP is the saturation pressure at the flash

point temperature.The saturation pressure can be obtained from the(Daniel A.Crowl,

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Joseph F.Louvar “Chemical Process Safety” , Second Edition , Prentice Hall Inc, 2002). Flash point is the parameter used to categorize the flammability of a chemical. For pure fluids, this property can be found in several references such as Chemical Properties Handbook.However for liquid mixtures, the availability of flash point values is extremely limited. Good experimental and estimation methods are needed to comply with the current regulations. Most of the methods available are focused primarily on pure compounds; however, most of the chemicals handled in industry are mixtures. The behavior of mixtures can be extremely different compared to their individual components. The flash point of a mixture will vary depending on the composition. If the mixture is considered an ideal solution ( 1≈iγ ) the applicability of Raoult’s law :

satiii PxPy = ……………..(2)

in combination with Le Chatelier’s mixing rule for predicting the LFL of mixtures:

∑=

= N

i i

imix

LFLy

LFL

1

1 ……………..(3)

and equation (1) are the simple approach to predict the flash point of mixtures.

3. Apparatus.

Pensky-Martens automated flash point Analyzer (FP93 5G2).

4. Theory

The ISL FP93 5G2 Analyzer is compact and self-contained. It can be globally

divided into two parts, the control unit and the test unit.

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4.1 Control Unit: The control unit on the left contains control logic boards, servo motors and also: In the front side -The screen -The keyboard -Contrast and brightness adjusting knobs -Test flame and pilot light adjusting knobs In the back side -The external link connectors (Printer etc.) -The mains connector and the On/Off switch -Gas alimentation nozzle In the lateral right side or connection panel -The connectors of the sample temperature probe, the flash detection device and the igniter. -Gas supply connecting tubes -Test and stirring transmission arms housing The test arm has a double function: opening the test cover shutter and tip up the igniter in the test cup. Both these arms are presented automatically during testing and are retracted into their control unit housings at the end of testing. 4.2 Test Unit: The test unit on the right containing the elements specific to the Pensky-Martens flash point method: -The heating block with recess (or well) to receive the test cup and rapid cooling system - The standby support for the test cover (it can also receive the test cup) 4.2.1 Heating Block A wall heating element provides heating for the metallic test cup well. During testing, the test cup is placed in this well. An integrated thermocouple measures the temperature in the heating block. 4.2.2 Cooling system An air flow is generated by a fan located at the rear of the heating block. The fan takes in fresh air at the back of the unit and hot air is blown throughout a grid at rear of the heating block. With the test cup and cover in place and the sample having been heated to 300C, the heating block can be cooled to 50C in 10 minutes.

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4.4.3 Stirring System The stirrer is mounted on the test cover. The stepping motor for the stirrer drive arm is located in the control unit. The drive arm is presented automatically during testing and retracted into its control unit housing at the end of testing. If the test cover is absent or incorrectly fitted, the stirring system will detect this according to the arm position and indicate this anomaly by an alarm. An audio alarm is triggered and the test stops. 4.4.4 Ignition The type of ignition system is automatically detected and indicated in the test menu screen by a letter in brackets in the Run Test menu: -(E) for an electrical igniter -(G) for a gas igniter If, when a test is started, no igniter is connected, the test stops. The connector of the igniter is on the connection panel of the control unit. The igniter support and the including mechanism are mounted on the cover. Opening the flap allows the igniter to be lowered into the cover. 4.4.4.1 Test Flame and pilot light The test flame lights automatically at the beginning of a test. If the test flame happens to go out, a pilot light will rapidly relight the test flame, the two flames being in contact in the idle position. If the test flame and the pilot light are both out, a detection system will light up a glow plug that relights both flames. During a test, if the test flame is absent for more than 2 minutes, or if the flame is absent at the moment of presentation, the test will stop. Gas supply is controlled by a solenoid valve and the operator may adjust the test flame by means of a valve screw knob on the front side of the control unit. The SV gas inlet is at the rear of the control unit panel. The test flame igniter is equipped with a flame detection and ignition device. The igniter arm having been positioned on selecting “Run Start”, if the test flame is not lit immediately, the system will attempt to light it during 10 min. If after this delay it is not lit, the test is stopped. During test, if the test flame is absent for 1 min or if it is absent at the moment of a test flame presentation, the test is stopped. -Gas used: Propane or Butane -Inlet pressure: 40 mbar maximum -Inlet operating pressure: 28mb 4.4.4.2 Gas Flame Adjustment Two knobs in the Analyzer front panel enable the test flame and the pilot light to be adjusted.

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4.4.4.3 Electrical Ignition The glow plug comes on for 10 seconds at the beginning of a test, then goes out. It will come on again about 30 seconds before each test. The current may be read on the “Test Running” screen. During a test, glow plug current is around 10 A to 13 A. If the glow plug current goes outside these limits, the test will stop. 4.4.5 Flash Point Detector The flashpoint is detected by a thermocouple or a ring-shaped ionization electrode. The flash detector is mounted on the test cover and either version can be easily disassembled and reassembled. The flash detector is connected on the control unit panel of the test unit. Once the flash point has been detected, the test is stopped. The green indicator on the control unit panel of the test unit illuminates on a flash detection. 4.4.6 Sample Temperature Probe The Pt100 Platinum temperature probe is placed in a holder in the test cover and is connected on the near side of the control unit panel of the test unit. Measuring range is -100 to +400C. 4.4.7 The Test Arm In standby, the igniter / shutter operating arm or test arm is located on the control unit panel. Just like the stirrer arm, it is positioned at the beginning of the test and automatically opens the shutter at igniter presentation temperatures. The opening movement of the shutter dips the igniter (gas or electrical) into the test cover opening. The shutter is automatically closed after presentation of the igniter. The arm is retracted into its control unit housing at the end of the test.

5. Experimental Procedure

1. Fill the test cup with the test specimen to the filling mark inside of the test cup. If too much specimen has been added, use a syringe or similar device to remove the excess.

2. Place the cup in the heating block. The 2 protruding notches of the heating block are used as guides for the 2 slots on the top rim of the cup.

3. Place the test cover on the test cup. 4. Turn the cover handle clockwise to block the assembly in position. Make sure

that the locking device is correctly engaged. 5. Connect up the flash detector and the sample temperature probe and insert the

probe into its holder in the test cover, if it is not already in its cover support. 6. Select “Run menu” from initial screen. 7. Enter the following information on the next screen.

a. Sample ID: Sample identifier b. Sample No: Sample Number c. EFP: Expected Flash Point d. Test: Type of test, for example ASTM D93 A/B, IP 34 A/B etc.

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e. Operator: Operator’s name. f. Exit: exit to main menu g. Next No: Increment the sample number h. Previous EFP: For using the previous test EFP. i. RUN START (E/G): This function is used to start the test selected on

the screen. If no ignition device is connected, the field between brackets still blank ().

j. Display: This function switches the Analyzer to the 4-digit sample temperature “TEST RUN” display. This “TEST RUN” screen is automatically activated at test start. The expected flash point, the Analyzer status, the date , the time and the glow plug current (when it is used) are also displayed.

k. Down: This key allows the user to display the page numbers allocated to the results.

l. The temperature, “T” and the no. of igniter applications, “A”, are displayed at the bottom of the screen. These values evolve during a test.

8. If the apparatus has been correctly prepared, you are now ready to start a test run. A “RUN START ( )” function is provided for this purpose. When this function selected, the next screen displays:

a) EFP: Expected Flash Point b) Analyzer: Current status of the analyzer c) Applications: The number of applications of the igniter. d) Flame Test: To present the igniter (at any time) during a test run e) Exit: Back to test run screen.

The date, the time and the intensity of the glow plug current.

During the igniter application, the great size temperature display is locked. The display will be unlocked only if the flash point has not been detected. Thus if the flash point is detected, the detection temperature will still be displayed after the test automatic stop.

9. The test can be stopped manually at any time during a test run by pressing the

“STOP” key on the keypad. Confirm the current test stop by selecting “OK” at screen.

10. When the flash point is detected, an intermittent audio alarm is triggered. To stop

the alarm press the “STOP ALARM” button on the keyboard. The “End of Test” screen will be displayed. Select “QUIT”. Quitting gives a screen called “End of test” screen. The flash point temperature remains displayed when the test is stopped. On the first line below the large “ Sample temperature display” are displayed:

a) the EFP at the first automatic igniter presentation b) the number of igniter application until the flash point

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c) “FLASH” temperature of detected flash point. The stirrer drive arm and the shutter/igniter presentation arm return to their housings. Fast cooling of the heating block is started up until the “Cooling temperature limit” is reached. 6. Results and Discussion:

1. Plot the different compositions of given liquid samples versus their respected flash point.

2. Discuss the importance of flash point and fire point in the transportation and

storage of dangerous materials.

3. Discuss the importance of flash point experiment when there is no data available in the literature for mixtures having different compositions.

4. Compute the LFL of each pure liquid component and use this information to

calculate the LFL of mixtures using equations (1) and (3) above. 7. Safety Precaution

7. Wear eye protection at all times. 8. Wear jeans or slacks, a long sleeved shirt, and sturdy shoes that give good

traction on possibly wet floors. 9. Guard against electrical hazards by making sure that all equipment is well

grounded using three-wire plugs and other means. 10. Handle with great care any solvents or other potentially volatile,

flammable, toxic, or otherwise dangerous chemicals. 11. Guard against falls, burns, cuts, and other physical hazards. Use heavy

gloves to open or close hot steam or condensate valves. 12. Wear vapor masker when you handling a hazardous volatile chemical in an

open containment 13. Think first of safety in any action you take. If not certain, ask the TA or

faculty member before you act.

8. References:

Daniel A.Crowl, Joseph F.Louvar “Chemical Process Safety” , Second Edition , Prentice Hall Inc, 2002.

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Experiment 3: Loss of Containment of Liquid 4. Learning Objectives

1.1. To determine the effect of pressure head on mass flow rate of liquid for

orifice having same size but at different levels.

1.2. To determine the effect of pressure head on mass flow rate of liquid for

orifice having different size but at same level

2. Introduction

Most accidents in chemical plants result in spills of toxic, flammable and

explosive materials. Accidents begin with an incident, which usually results in the loss of containment of material from the process. The material has hazardous properties which might include toxic properties and energy content. Typical incidents might include the rupture or break of a pipeline, a hole in a tank or pipe, runaway reaction, or fire external to the vessel. Once the incident is known, source models are selected to describe how materials are discharged from the process.

2.1 Source Model

The source model provides a description of the rate of discharge, the total

quantity discharged (or total time of discharge), and the state of the discharge (that is, solid, liquid, vapor or a combination). A dispersion model is subsequently used to describe how the material is transported downwind and dispersed to some concentration levels. For flammable releases fire and explosion models convert the source model information on the release into energy hazard potential such as thermal radiation and explosion over pressure. Effective models convert these incident-specific results into effects on people (injury or death) and structures. Additional refinement is provided by mitigation factors, such as water sprays, foam systems, and sheltering or evacuation, which tend to reduce the magnitude of potential effects in real incidents.

Source models are constructed from fundamental or empirical equations representing the physicochemical processes occurring during the release of materials. For a reasonably complex plant many source models are needed to describe the release. Some development and modification of the original model is normally required to fit the specific situation. Frequently the results are only estimates because the physical properties of the materials are not adequately characterized or because the physical processes themselves are not completely understood. If uncertainty exists, the parameters should be selected to maximize the release rate and quantity. This ensures that a design is on the safe side.

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2.2 Release mechanism

Release mechanisms are classified into wide and limited aperture releases. In the wide aperture case a large hole develops in the process unit, releasing a substantial amount of material in a short time. An excellent example is the over pressuring and explosion of a storage tank. For the limited aperture case material is released at a slow enough rate that upstream pressure conditions are not immediately affected; the assumption of constant upstream pressure is frequently valid. 3. Apparatus:

The Loss of Containment of Liquid apparatus consists of following components: No. Part Type Description Quantity 1 Tank Liquid Containment

Tank Derived from Fabricated Pressurized Receiving Tank

1

2 Pump Water Pump Centrifugal Type 1 3 Valves a)Ball valves

b)Solenoid Valve c)Check Valve

On/Off type with 2 inch leverage and ½ inch connection size Parker brand, Normally Open type with 2 inch connection port and 50 mm orifice size. Flow rate is 37.20 m3/hr. Stainless Steel. Suitable for water. Connection O/D ¼ inch

8 1 1

4 Orifice Spray Nozzle a)Orifice 1 b)Orifice 2A c)Orifice 3 d) Orifice 4 e)Orifice 2B f)Orifice 2C

VeeJet brand,0 degree spray angel nozzle type Orifice Flow Rate:19.7LPM Connection:1/4inch NPT Orifice Flow Rate:11.5LPM Connection:1/4inch NPT Orifice Flow Rate:32LPM Connection:1/4inch NPT Orifice Flow Rate:38LPM Connection:3/8inch NPT Orifice Flow Rate: 11.5LPM Connection:1/4inch NPT Orifice Flow Rate:11.5LPM Connection:1/4inch NPT

1 1 1 1 1 1 1

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g)Orifice 2D

Orifice Flow Rate:11.5LPM Connection:1/4inch NPT

1

5 Transducer Differential Pressure Transducer

Honeywell brand,0-5 psi with full span output is 50mv

1

6 Pressure Switch

Adjustable Pressure Switch

Herga brand. Setting Accuracy of +%10 that withstand a pressure of 500psi. Ambient temperature range of 5C to +70C Switching-2separate switches, single pole changeover. Ratings: 250VAC21(8)A

1

7 Indicator Temperature Indicator

Oregon Scientific Electronic LCD thermometer. C/F switch able with temperature range of 0C to +50C (Indoor) / 50C to +70C (Outdoor)

1

4. Theory

A hole/orifice develops at certain height in a tank and causes drop in liquid

level in the tank. The flow of the liquid from the hole or orifice depends upon the size

of orifice, height of liquid and pressure over the liquid surface. The instantaneous

mass flow rate of the liquid from the tank can be calculated as follows:

LghgcPgACoQm +⎟⎟⎠

⎞⎜⎜⎝

⎛=

ρρ 2

Where

ρ is the fluid density

A is the area of orifice

Co is the discharge coefficient

gc is the gravitational constant

g is the acceleration due to gravity

Pg is the pressure of the gas over the liquid surface

hL is the liquid height

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5. Experimental Procedure: 1. Ensure all On/Off ball valves (Ball valve 1, Ball Valve 2, Ball

Valve 3 & Ball Valve 4, & Orifice 1, 2A, 2B, 2C, 2D, 3 & 4)

are in close position.

2. Turn on the water supply to fill the liquid containment tank to

a certain level.

3. Observe the water level in the liquid containment tank using

level sight tube and close the water supply valve when certain

level is achieved.

4. Note the water level position in level sight tube.

5. Turn on the compressed air inlet ball valve 1 and pressurize

the liquid containment tank to 3 bar.

6. Close the compressed air inlet ball valve 1.

7. Turn on orifice 2A and note the time for water discharge until

there is no more water flow out of the orifice.

8. Repeat from step 2 to step 7 for orifice 2B, 2C & 2D having

same size as of orifice 2A but at different levels.

9. Repeat the same experiment for pressures 2 bar.

10. After completing the experiment, open the vent ball valve 2

to release the pressure inside the tank and drain ball valve 4

to drain the water left in the tank.

Note: Repeat the same experiment with orifice 1, 2A, 3 & 4 having different sizes but located at same level.

6. Observations: 6.1. Orifices having same size but at different level Pressure: 3 bar

Liquid level (cm)

Discharge Time (sec)

Instantaneous mass flow rate

(Qm)

Orifice No. Orifice Size (mm)

Start End Height 1 2 3 4 Repeat the above experiment with pressure 2 bar.

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6.2. Orifices having different sizes but at the same level Pressure: 3 bar

Liquid level (cm)

Discharge Time (sec)

Instantaneous mass flow rate

(Qm)

Orifice No. Orifice Size (mm)

Start End Height 1 2 3 4 Repeat the above experiment with pressure 2 bar. 7. Results and Discussion:

1. Plot the pressure head versus instantaneous flow of liquid for different size and position of orifices.

2. Discuss the effect of pressure head on Instantaneous flow of liquid for

different size and position of orifices.

3. Discuss the importance of this experiment in context of handling liquid materials at the workplace.

8. Safety Precaution

14. Wear jeans or slacks, a long sleeved shirt, and sturdy shoes that give good traction on possibly wet floors.

15. Guard against electrical hazards by making sure that all equipment is well grounded using three-wire plugs and other means.

16. Think first of safety in any action you take. If not certain, ask the TA or faculty member before you act.

9. References:

Daniel A.Crowl, Joseph F.Louvar “Chemical Process Safety” , Second Edition , Prentice Hall Inc, 2002.

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Experiment 4: Loss of Containment of Gas 1. Learning Objectives

1.1 To determine the effect of pressure head on maximum flow of gas for

orifice having different size but at same level

1.2 To determine the effect of pressure head on maximum flow of gas for

orifice having same size but at different levels

2. Introduction

Most accidents in chemical plants result in spills of toxic, flammable and

explosive materials. Accidents begin with an incident, which usually results in the loss of containment of material from the process. The material has hazardous properties which might include toxic properties and energy content. Typical incidents might include the rupture or break of a pipeline, a hole in a tank or pipe, runaway reaction, or fire external to the vessel. Once the incident is known, source models are selected to describe how materials are discharged from the process.

2.1 Source Model

The source model provides a description of the rate of discharge, the total

quantity discharged (or total time of discharge), and the state of the discharge (that is, solid, liquid, vapor or a combination). A dispersion model is subsequently used to describe how the material is transported downwind and dispersed to some concentration levels. For flammable releases fire and explosion models convert the source model information on the release into energy hazard potential such as thermal radiation and explosion over pressure. Effective models convert these incident-specific results into effects on people (injury or death) and structures. Additional refinement is provided by mitigation factors, such as water sprays, foam systems, and sheltering or evacuation, which tend to reduce the magnitude of potential effects in real incidents.

Source models are constructed from fundamental or empirical equations representing the physicochemical processes occurring during the release of materials. For a reasonably complex plant many source models are needed to describe the release. Some development and modification of the original model is normally required to fit the specific situation. Frequently the results are only estimates because the physical properties of the materials are not adequately characterized or because the physical processes themselves are not completely understood. If uncertainty exists, the parameters should be selected to maximize the release rate and quantity. This ensures that a design is on the safe side. 2.2 Release mechanism

Release mechanisms are classified into wide and limited aperture releases. In the wide aperture case a large hole develops in the process unit, releasing a substantial

22

amount of material in a short time. An excellent example is the over pressuring and explosion of a storage tank. For the limited aperture case material is released at a slow enough rate that upstream pressure conditions are not immediately affected; the assumption of constant upstream pressure is frequently valid. 3. Apparatus:

No. Part Type Description Quantity 1 Valves a)Ball valves

b)Solenoid Valve

On/Off type with 2 inch leverage and ½ inch connection size Parker brand, Normally Open type with 2 inch connection port and 50 mm orifice size. Flow rate is 37.20 m3/hr.

8 1

2 Orifice Spray Nozzle a)Orifice 1 b)Orifice 2A c)Orifice 3 d) Orifice 4 e)Orifice 2B f)Orifice 2C g)Orifice 2D

VeeJet brand,0 degree spray angel nozzle type Orifice Flow Rate:19.7LPM Connection:1/4inch NPT Orifice Flow Rate:11.5LPM Connection:1/4inch NPT Orifice Flow Rate:32LPM Connection:1/4inch NPT Orifice Flow Rate:38LPM Connection:3/8inch NPT Orifice Flow Rate: 11.5LPM Connection:1/4inch NPT Orifice Flow Rate:11.5LPM Connection:1/4inch NPT Orifice Flow Rate:11.5LPM Connection:1/4inch NPT

1 1 1 1 1 1 1 1

3 Transducer Differential Pressure Transducer

Honeywell brand,0-5 psi with full span output is 50mv

1

4 Pressure Switch

Adjustable Pressure Switch

Herga brand. Setting Accuracy of +%10 that withstand a pressure of 500psi. Ambient temperature range of 5C to +70C

1

23

Switching-2separate switches, single pole changeover. Ratings: 250VAC21(8)A

5 Indicator Temperature Indicator

Oregon Scientific Electronic LCD thermometer. C/F switch able with temperature range of 0C to +50C (Indoor) / 50C to +70C (Outdoor)

1

6 Fog Machine

Smoke Power: AC 120V/60Hz or 230V/50Hz Heater: 700W. Warm-up: 4 minutes. Tank Capacity:0.7 Litre Weight: 4.5Kg Dimensions:333x160x130mm

4. Theory

For flowing liquids the kinetic energy changes are frequently negligible and the physical properties (particularly the density) are constant. For flowing gases and vapors these assumptions are valid only for small pressure changes (P1/P2<2) and low velocities (<0.3 times the speed of sound in gas). Energy contained within the gas or vapour as a result of its pressure is converted into kinetic energy as the gas or vapor escapes and expands through the hole. The density, pressure, and temperature change as the gas or vapour exits through the leak.

Gas and vapour discharge are classified into throttling and free expansion releases. For throttling releases the gas issues through a small crack with large frictional losses; little of the energy inherent to the gas pressure is converted to kinetic energy. For free expeansion releases most of the pressure energy is converted to kinetic energy, the assumption of isentropic behaviour is usually valid. .Free expansion release source models require only the diameter of the leak. The maximum flow is determined by the following equation:

( ) ( )1/1

12

−+

⎟⎟⎠

⎞⎜⎜⎝

⎛+

=γγ

γγRgTogcMCoAPoQm

Where M is the molecular weight of the escaping vapour or gas To is the temperature of the source and

24

Rg is the ideal gas constant γ is the heat capacity ratio (Cp/Cv) A is the area of orifice Co is the discharge coefficient gc is the gravitational constant Po is the pressure inside process unit 5. Experimental Procedure:

1. Ensure all on/off ball valves(ball valve 1, ball valve 2, orifice

1, 2A, 2B,2C,2D, 3 & 4) are closed.

2. Turn on the compressed air inlet ball valve 1 and pressurize

the gas containment tank to 4 bar.

3. Close the compressed air inlet ball valve 1.

4. Turn on orifice no.1 and note the time for air discharge while

looking at pressure gauge until there is no more air flow out

of the orifice.

5. Repeat from step 2 to step 4 for orifice no. 2A, 3 & 4 having

different size as of orifice no.1 but at same level.

6. Repeat the same experiment by adjusting pressure 3, 2, and

1.0 bar.

7. After completing the experiment, turn on the drain ball valve

2 to release the pressure left in the pressure containment tank.

Note: Repeat the same experiment with orifice no. 2A, 2B, 2C & 2D having

same size but at different levels

6. Observations: 6.1. Orifices having different sizes but at the same level Pressure= 4bar

Orifice No. Orifice Size (mm)

Discharge Time (sec)

Instantaneous mass flow rate

(Qm) 1 2 3 4 Repeat the above experiment with pressure 3 bar.

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6.2. Orifices having same size but at different level Pressure= 4bar

Orifice No. Orifice Size (mm)

Discharge Time (sec)

Instantaneous mass flow rate

(Qm) 1 2 3 4 Repeat the above experiment with pressure 3 bar. 7. Results and Discussion:

1. Plot the pressure head versus maximum flow of gas for different size and position of orifices.

2. Discuss the effect of pressure head on maximum flow of gas for different size and position of orifices.

3. Discuss the importance of this experiment in context of handling

ldifferent gaseous material materials at the workplace. 8. Safety Precaution

17. Wear jeans or slacks, a long sleeved shirt, and sturdy shoes that give good traction on possibly wet floors.

18. Guard against electrical hazards by making sure that all equipment is well grounded using three-wire plugs and other means.

19. Think first of safety in any action you take. If not certain, ask the TA or faculty member before you act.

9. References:

Daniel A.Crowl, Joseph F.Louvar “Chemical Process Safety” , Second Edition , Prentice Hall Inc, 2002.

26

Experiment 5: Bomb Calorimetry 1. Learning Objectives

1.1 To understand the importance of characterizing runaway reactions.

1.2 To determine the gross calorific value of a certain fuel sample.

1.3 To familiarize with a calorimeter system.

2. Introduction

Enthalpies of combustion can be determined reliably using bomb calorimetry. This

technique was once widely used in physical chemistry, since it provides

thermodynamic data in a very direct way, and is still used in the fuel and food

industries.

To measure enthalpies of

combustion, we burn a

known amount of material

in a bomb calorimeter and

determine the temperature

change. The bomb is

pressurized with oxygen to

ensure complete

combustion, and sealed to

prevent escape of the

combustion products. The

compound is ignited by

passing a current through a fuse wire within the bomb. Allowance for the heat

capacity of the bomb is made by igniting a known quantity of a substance of known

enthalpy of combustion as a standard. Heat loss to the surroundings can be calculated

by use of a cooling correction curve, or, as in this experiment, prevented by use of a

jacket around the calorimeter, maintained at the same temperature as the calorimeter

itself; the reaction is then adiabatic.

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2.1 Runaway reaction

A runaway reaction is a type of scenario that requires special data for relief sizing.

Physical property data and sometimes reaction rate characteristics are required for

making relief sizing calculations. Data estimated using engineering assumptions are

almost always acceptable when designing unit operations because the only results are

poorer yields or poorer quality. In relief design, however, these types of assumptions

are not acceptable because an error may result in catastrophic and hazardous failures.

It is known that runaway reactions nearly always result in two-phase flow reliefs. The

two phases discharge through the relief system. When conditions change rapidly, as in

a runaway reaction scenario, two phase flow calculations are relatively complex.

Thus, special methods have been developed to acquire relevant data and for making

the relief vent sizing calculations.

2.2 Calorimeters

Several commercial calorimeters are available to characterize runaway reactions. All

of there adiabatic calorimeters work the same way. The sample to be tested is heated

by means of one of two modes. In the first mode, the sample is heated to a fixed

incremental temperature and then the calorimeter maintains this temperature and waits

a fixed time to determine whether an exothermic reaction occurs. If no reaction is

detected, then the temperature is increased by another increment. In the second

heating mode, the sample is heated at a fixed temperature rate and the calorimeter

watches for a higher rate that identifies the initiation of the exothermic reaction. Some

calorimeters use a mix of the two modes. The data that be obtained from the

calorimeters include maximum self-heat rate, the maximum pressure rate, reaction

onset temperature and the temperature and pressure as a function of time.

For relief sizing calculation, important results include temperature rate (dT/dt)s at the

set pressure and the temperature increase ∆T corresponding to the overpressure ∆P.

Because the calorimeter starts with known weights and known composition, the heat

of reaction can also be determined from the T versus t data.

28

3. Apparatus and Chemicals

Apparatus : IKA-Calorimeter System

4. Theory

4.1 Determining the gross calorific value

In a calorimeter, combustion processes take place under precisely defined conditions.

For this purpose, the decomposition vessel is charged with a weighed-in fuel sample,

the fuel sample is ignited and the increase in temperature in the calorimeter system is

measured. The specific gross calorific value of the sample is calculated from:

• The weight of the fuel sample

• The heat capacity (C value) of the calorimeter system

• The increase in temperature of the water in the inner vessel of the

measurement cell

To optimize the combustion process, the decomposition vessel is filled with pure

oxygen (99.95%). The pressure of the oxygen atmosphere in the decomposition vessel

is 30 bar. The exact determination of the gross calorific value of a substance is based

on the requirement that the combustion proceeds under precisely defined conditions.

The applicable standards are based on the following assumptions:

• The temperature of the substance to undergo combustion is 22°C before

combustion.

• The water contained in substance and the water formed during combustion

of compounds in the substance containing hydrogen, are present in liquid

state after combustion.

• No oxidation of atmosphere nitrogen takes place.

• The gaseous products of combustion consist of oxygen, nitrogen, carbon

dioxide and sulfur dioxide.

• Solid ash is formed.

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4.2 Complete Combustion

To determine the gross calorific value correctly, it is of fundamental significance for

the sample to be burned completely. After the experiment, the crucible and all solid

residues must be examined for signs of incomplete combustion.

5. Experiment for Gross Calorific Value Determination

5.1 Experimental Procedures

NOTE: After the system has been switched on, it requires about 30 minutes until the

stable temperature conditions are prevalent in the measurement cell.

[1] Make sure that the decomposition vessel is clean and dry.

[2] Weigh chemical directly into the crucible.

[3] Place the crucible into the decomposition vessel.

[4] Suspend the decomposition vessel into the open measurement cell cover until

it reaches the stopper. The message Bomb ↓ on the bottom line of the screen

should change to a display of the function key assignment Start.

[5] Active Start. The measurement cell cover closes. The decomposition vessel is

then filled with oxygen. Next, the inner vessel is filled with water. As soon as

the system begins with the experiment, the display shows a graph of the

change over time in temperature of the inner vessel.

[6] The sample is then ignited and the change in temperature of the inner vessel

over time is recorded.

[7] At the end of the experiment, the system displays the results of the

experiment.

[8] The decomposition vessel is vented and the measurement cell cover opens.

[9] As soon as the message Bomb ↓ appears, remove the decomposition vessel

and open it.

[10] Check the crucible for combustion residue. Fuel sample must be burned

completely. Repeat experiment if there are any signs of incomplete

combustion.

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5.2 Results and Discussion

a) From the system display, transfer the data to plot a graph of change in temperature

over time.

b) Determine the heat of reaction/combustion from the T versus t graph.

c) Compare the calculated value with values obtained from literature review.

5.3 Calculation of Gross Calorific Value

Room temperature = TR = ______ °C

Weight of sample = W = _______ g

Volume of water in Calorimeter = V = 2500 ml

Density of Water at TR = ρw = ______ g/cc

Mass of water = M = (density x volume) = ______ g

Specific heat of water at TR = Cp _______ cal / g - °C

Initial temperature of water = T1 = ______ °C

Final temperature of water = T2 = ______ °C

Maximum rise in temperature = ΔT = T2 – T1 = ______ °C

G.C.V = M x Cp x ΔT = ______ cal / g W

6. Precautions:

1. Keep the bomb clean; when you dismantle it, place it on a clean folded towel or stand. Be careful not to scratch or drop the bomb.

2. Switch off all power when adding the bomb or removing it from the

calorimeter.

3. Do not use more than 1.0 g of solid.

4. Do not fire the bomb if bubbles of gas show it is leaking (less than 1 bubble per three seconds is insignificant.)

5. Stand clear of the top of the calorimeter when it is fired, and for 20 seconds

afterwards.

6. Be careful when moving the calorimeter lid, since the thermometers which stick through it are very vulnerable.

7. Bomb calorimeters require care to operate, so do not hesitate to ask for

assistance from a demonstrator.

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Experiment 6 : Noise Level Analysis 1. Learning Objective To observe the principles of noise pollution control and measure the noise level using sound meter. 2. Introduction The human ear is divided into three parts, the external, the middle, and the inner ear. The external ear captures, collects and transports sound to the eardrum. The eardrum is a thin piece of tissue, which separates the external ear from the middle ear. It converts the sound waves to mechanical vibration. The middle ear transports the vibration to the inner ear. The inner ear contains receptors that detect the vibration and convert the signals to electrical impulses that are then transported to the brain where interpretation takes place. Hearing can be defined as the ability to receive and process sound. Hearing is an important function for communication. The loss of this ability bears important consequences to day-to-day life. Hearing loss can be broadly defined as the decreased ability to receive or process sound. It has several causes, which can be classified into five groups: conductive, sensor neural, mixed, central or functional. Hearing loss is very common in our society, its incidence is approximately 0.2% in those under 5 years of age, 5% in those 35-54 years of age, 15% of those 55-64 years of age and 40% (or more) in those over 75 years of age. As one ages, the likelihood of hearing loss increases. The human ear detects sound, which is a form of energy. Sound is a longitudinal, mechanical pressure wave that results from vibrating objects and can be transmitted through air, water and solid. Like other waves, sound waves vary in intensity, frequency, harmonic motion and direction. The frequency of a particular sound relates to its number of wave cycles per second. It is measured in Hertz (1 cycle per second = 1 Hertz). Frequency is perceived as the pitch of a sound. The higher the frequency, the higher the pitch and vice versa. The normal human ear is able to detect frequencies from about 20 Hertz to 20,000 Hertz. The speech frequencies i.e. those frequencies most important for human hearing are from approximately 250 Hertz to 4,000 Hertz.

32

The intensity of sound is perceived as loudness. It is measured on a relational scale with the unit of measurement being the decibel. Sound intensities require a standard sound level against which they are compared. The standard sound pressure level (SPL = 0 dB) is 0.0002 dynes/cm2. The decibel is a numeric value that represents sound intensity with respect to the reference sound pressure level. Sound intensity is measured on a logarithmic scale. An increase of 6 dB of sound pressure is perceived as double the intensity of the sound.

TABLE: Sound pressure levels of common sounds

SOUND dB

Rocket launching pad 180 Jet plane 140 Gunshot blast 130 Car horn 120 Pneumatic drill 110 Power tools 100 Subway 90 Noisy restaurant 80 Busy traffic 75 Conversational speech 66 Average home 55 Library 40 Soft whisper 30

In a workplace, an employee might experience two or more periods of noise exposure at different pressure levels. When this is the case, their combined effect, or the employee’s effective daily dose, can be calculated by the following equation.

n

nn

i i

i

TC

TC

TC

TC

D +++== ∑=

...........2

2

1

1

1

where D is the effective daily dose (of noise) to which the employee has been exposed to, Ci is the time period during which the employee has been exposed to sound pressure level i and Ti is the maximum time period during which the employee may be safely exposed to sound pressure level i. Ti may be estimated from the following.

33

( ) 59028−=

iLiT

where Li is sound pressure i measured in dBA. For values D [ 1.00, the employee will have accumulated neither an excessive nor harmful amount of noise exposure. On the other hand, if D > 1.00, the exposure then would have to be classified as potentially harmful. Running machinery (e.g. ventilation and air-conditioning units, heating installations, motor engines, office equipment) is a major source of noise pollution. When noise pollution becomes excessive, it becomes necessary to control the noise level. The understanding of the physical principles behind noise, and vibration, generation and transmission is essential in understanding the functional effectiveness and deficiencies of the various forms of noise control measures. One approach to noise control is to reduce the noise at its source. This involves modification of the physical processes and/or equipment that are responsible for generating the noise. A vibrating structure radiates sound, which can be damped by altering the structure’s stiffness and/or mass. Alternatively, the sound radiated may be reduced by decoupling the structure from the vibration source, that is, by isolating the vibration. Another approach to noise control is to modify the noise transmission path. Noise may be transmitted from source to receiver through the surrounding air, liquid and/or solid. Transmission paths may be modified by placing barriers or screens between the source and receiver, as in the case of noise control enclosures placed around machinery. Transmission paths may also be modified by dissipating some of the propagating energy through the use of sound absorbing materials. 3. Apparatus 1. Extech Datalogging Sound Level Meter (Model 407764) 2. P.A. Hilton Noise Control Demonstration Unit, which comprises the following components: The baseboard – A metal plate is moulded into the baseboard through which an 8 mm diameter bolt is screwed. This can be made to bear onto the lower face of the mounting platform, thereby short circuiting the flexibility of the anti-vibration

34

mountings. The bolt head is attached to a 300 mm diameter plastic disc below the baseboard by which the bolt is controlled and can be operated externally. A noise and vibration generator (the motor and gearbox of an electric drill) – The speed of rotation is variable so as to allow the frequency spectrum and sound output to be varied. An out-of-balance rotor can be clamped in the drill church to promote an increase in vibration response. The unit is clamped on to the frame held above the baseboard by four anti-vibration mountings. A noise and air flow generator – Contains a small fan driven directly by a variable speed motor with an attendant unloaded gearbox that drives air through tubes representing components of an air conditioning system. The gearbox creates suitable background noise.

35

FIGURE: P.A. Hilton Noise Control Demonstration Unit A noise control box of rigid GRP – The box is designed to cover the noise source. This has a removable absorbent lining, which may be used on its own. Both have access holes for the fitting of plugs and air tubes. There is a clamping mechanism to attach the box to the baseboard.

36

The control and instrument panel – The panel carries all the controls and instruments necessary for the correct functioning of the equipment. Controls and instruments include speed control and noise measurement by means of an LED analogue indicator. Two microphones are provided. One is mounted alongside the noise sources and is placed within the noise control box when the box is being used. The other is fixed on to the end of a 300 mm length of 7 mm diameter tube that can be moved about to various locations outside the noise control box and inside the ventilation ducts. Miscellaneous – There is a stainless steel bar that acts as an inertia block when fixed to the generator mounting. There are two plastic tubes representing ventilation ducts with sound absorbent linings, and with two inner tubes that slide inside the absorbent linings to control the effective length of lining. 4. Experimental Procedure 1. Switch on the sound meter. 2. Select the frequency weighting (A). 3. Select the desired respond time (fast or slow). 4. Set the desired sound pressure range (30–130 dB). 5. Install the meter onto its tripod. For each of the following test, record the noise level say 10 readings with intervals of one minutes. (Note: Please switch off when not using the sound meter) Test 1: Rigid body modes of vibration of a resiliently mounted source

1. Clamp the noise and vibration generator onto the generator-mounting platform.

2. With the main power switched off and the voltage control set to minimum (i.e. at the most anti-clockwise position), insert the generator power plug into the 240 V socket.

3. Switch on the voltage on the console to 240 V.

4. Switch on the main switch and adjust the voltage control slowly, in the clockwise direction.

5. Note your observations.

37

Test 2: Effect of mass on the modes of vibration

6. Repeat steps 2 to 5, but with the stainless steel inertia block clamped onto the generator-mounting platform.

7. Note the difference in vibration and sound with and without the inertia block at the same speed setting.

Test 3: Effectiveness of sound-proofing materials

8. Remove the removable absorbent lining from the GRP noise control box.

9. Switch off the main power. Unclamp and remove the stainless steel inertia block from the generator-mounting platform.

10. Unplug the generator power plug from the 240 V socket.

11. Set the microphone switch to “External Microphone”.

12. Switch on the main power and adjust the zero adjuster so that the indicator bar display shows approximately 1 to 2 bars with the ambient noise.

13. Switch off the main power and insert the generator power plug into the 240 V socket.

14. Switch on the main power and adjust the voltage control until the motor is running at approximately ¾ full speed.

15. Place the absorbent lining over the generator.

16. Note any changes to the indicator display.

17. Repeat the test with the internal microphone.

18. Record your observations. Test 4: Effectiveness of sound-proofing materials

19. Repeat steps 9 to 17, with the GRP noise control box replacing the absorbent lining. When placing the control box over the generator, ensure that the box is securely clamped down, and that the apertures at the sides of the box are carefully sealed with hard plugs.

20. Record your observations.

38

Test 5: Effectiveness of sound-proofing materials

21. Switch off the main power and remove the noise control box. Reinstall the box’s absorbent lining.

22. Securely clamp down the control box, with its lining, over the generator. Ensure that the apertures are sealed with the soft plugs.

23. Switch on the main power.

24. Note your observations. Test 6: Effectiveness of sound-proofing materials

25. Remove the hard plugs from the apertures at the sides of the control sides, and replace with the plastic tubes, with absorbent lining and adjustable inner tubes, provided.

26. Slowly slide the inner tubes up and down the plastic tubes to adjust the effective length of the absorbent lining.

27. Record your observations.

39