Model 1305 MultiVolume Pycnometer - Micromeritics

Model 1305

MultiVolume Pycnometer

(S/N: 801 and higher)

Operator’s Manual

Part No. 135-42803-01March 2001

Swagelok is a registered trademark of Crawford Fitting Company.

© Micromeritics Instrument Corporation, 2001. All rights reserved.

WARRANTYMICROMERITICS INSTRUMENT CORPORATION warrants for one year from the date of shipment each instrumentmanufactured by it to be free from defects in material and workmanship impairing its usefulness under normal use andservice conditions except as noted herein.

Our liability under this warranty is limited to repair, servicing and adjustment, free of charge at our plant, of anyinstrument or defective parts, when returned prepaid to us, and which our examination discloses to have been defective.The purchaser is responsible for all transportation charges involving the shipment of materials for warranty repairs.Failure of any instrument or product due to operator error, improper installation, unauthorized repair or alteration, failureof utilities, or environmental contamination will not constitute a warranty claim. The materials of construction used inMICROMERITICS instruments and other products were chosen after extensive testing and experience for theirreliability and durability. However, these materials cannot be totally guaranteed against wear and/or decomposition bychemical action (corrosion) as a result of normal use.

Repair parts are warranted to be free from defects in material and workmanship for 90 days from the date of shipment.

No instrument or product shall be returned to MICROMERITICS prior to notification of alleged defect and authorizationto return the instrument or product. All repairs or replacements are made subject to factory inspection of returned parts.

MICROMERITICS shall be released from all obligations under its warranty in the event repairs or modifications aremade by persons other than its own authorized service personnel unless such work is authorized in writing byMICROMERITICS.

The obligations of this warranty will be limited under the following conditions:

1. Certain products sold by MICROMERITICS are the products of reputable manufacturers, sold under theirrespective brand names or trade names. We, therefore, make no express or implied warranty as to such products.We shall use our best efforts to obtain from the manufacturer, in accordance with his customary practice, the repairor replacement of such of his products that may prove defective in workmanship or materials. Service chargesmade by such manufacturer are the responsibility of the ultimate purchaser. This states our entire liability in respectto such products, except as an authorized person of MICROMERITICS may otherwise agree to in writing.

2. If an instrument or product is found defective during the warranty period, replacement parts may, at the discretionof MICROMERITICS, be sent to be installed by the purchaser, e.g., printed circuit boards, check valves, seals,etc.

3. Expendable items, e.g., sample tubes, detector source lamps, indicator lamps, fuses, valve plugs (rotor) and stems,seals and O-rings, ferrules, etc., are excluded from this warranty except for manufacturing defects. Such itemswhich perform satisfactorily during the first 45 days after the date of shipment are assumed to be free ofmanufacturing defects.

Purchaser agrees to hold MICROMERITICS harmless from any patent infringement action brought againstMICROMERITICS if, at the request of the purchaser, MICROMERITICS modifies a standard product or manufacturesa special product to the purchaser’s specifications.

MICROMERITICS shall not be liable for consequential or other type damages resulting from the use of any of itsproducts other than the liability stated above. This warranty is in lieu of all other warranties, express or implied,including, but not limited to the implied warranties of merchantability or fitness for use.

One Micromeritics Drive • Norcross, GA 30093-1877 • Fax: (770) 662-3696Domestic Sales — (770) 662-3633 Domestic Repair Service — (770) 662-3666International Sales — (770) 662-3660 Customer Service — (770) 662-3636

Form No. 008-42104-00Rev. 12/95

TABLE OF CONTENTS

1. GENERAL INFORMATION

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Equipment Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3Precautions and Intended Use . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

2. INSTALLATION

Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Equipment Damage or Loss During Shipment . . . . . . . . . . . . . . . 2-1Equipment Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Selecting the Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2Selecting the Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2Gas Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

3. OPERATION

Controls and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8Preparing and Weighing the Sample . . . . . . . . . . . . . . . . . . . . . . . 3-11Performing an Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12Calculating the Sample Volume, Density, and Specific Volume . . . . . . . . . 3-14Verifying Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

Zero Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15Scale Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

Calibrating the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16Definition of Volumes to be Calibrated . . . . . . . . . . . . . . . . . . . 3-16Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18

Turning Off the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19

4. TROUBLESHOOTING

Unstable Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Falling Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Rising Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Nonreproducible Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2Incorrect Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Model 1305 MultiVolume Pycnometer Table of Contents

Jun 99 i

Pressure Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Fails to Illuminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Constantly Indicates Nearly the Same Pressure . . . . . . . . . . . . . . 4-4

Slow Return to Zero Pressure Upon Venting . . . . . . . . . . . . . . . . . . . 4-5

5. ORDERING INFORMATION

APPENDICES

Appendix A: TheoryAppendix B: FormsAppendix C: Sample Results Computation ProgramAppendix D: Derivation of Calibration Equations

Table of Contents Model 1305 MultiVolume Pycnometer

ii Jun 99

CHAPTER 1

GENERAL INFORMATION

• Introduction

• Conventions

• Equipment Description

• Precautions and Intended Use

• Specifications

GENERAL INFORMATION

This manual describes how to install and operate the Model 1305 MultiVolumePycnometer.

Introduction

This manual is divided into chapters and appendices as follows:

Chapter 1 Provides a general description of the Model 1305 MultiVolumePycnometer and its specifications. Also provided in this chapterare precautions and intended use for the pycnometer.

Chapter 2 Describes how to unpack, inspect, and install the Model 1305MultiVolume Pycnometer.

Chapter 3 Provides a description of the controls and components of theModel 1305 Multivolume Pycnometer, as well as operating in-structions.

Chapter 4 Provides troubleshooting and user maintenance information.

Chapter 5 Provides ordering information for parts and accessories.

Appendix A Provides theoretical information concerning the Model 1305MultiVolume Pycnometer.

Appendix B Provides forms for you to copy and use when operating thepycnometer.

Appendix C Provides information on the computation program for sampleresults.

Appendix D Provides calibration calculations.

Model 1305 MultiVolume Pycnometer Introduction

Jun 99 1-1

Conventions

This manual uses the symbols shown below to identify notes of importance andwarnings.

Notes contain information pertinent to the subject matter.

Warnings contain information to help you prevent actions which couldcause personal injury.

Conventions Model 1305 MultiVolume Pycnometer

1-2 Jun 99

Equipment Description

Figure 2-1. The Model 1305 MultiVolume Pycnometer

The MultiVolume Pycnometer 1305 accomplishes the measurement of skeletal vol-umes by observing the reduction of gas capacity in the sample chamber causedby the presence of the sample. Since helium or most other suitable gases pene-trate even the smallest pores and surface irregularities, the volume obtained per-mits computation of the ultimate theoretical density of the solid comprising thesample if there are no closed pores.

The sample chamber with the sample present is first charged to a gas pressure ofabout 20 psig (unit of measure for the Model 1305). Subsequent expansion ofthis gas charge into a second precisely measured volume which previously was atthe same temperature and at zero psig results in a second pressure which be-comes progressively smaller for larger samples. Application of mass balance equa-tions for the gas permits easy computation of the sample volume when thevolumes of the empty sample chamber and the expansion chamber are knownand the pressure drop ratio upon expansion is known.

The MultiVolume Pycnometer 1305 differs from similar products in that three dif-ferent size sample chamber configurations are provided, each containing an associ-ated expansion volume sized to provide the maximum accuracy and resolution forthat range. A schematic diagram of the MultiVolume Pycnometer 1305 is shownin Figure 1-2. Theoretical information is provided in Appendix A.

Model 1305 MultiVolume Pycnometer Equipment Description

Jun 99 1-3

Figure 1-2. Schematic Diagram of the Model 1305

Gas In

FILL RATEValve

Over-PressureRelief Valve

FILL Valve Filter

PressureTransducer

SampleChamber

VENT RATEValve

VENTValve

<5/>5 Valve

<35/>35 Valve

PREP/TEST Valve

Equipment Description Model 1305 MultiVolume Pycnometer

1-4 Jun 99

Precautions and Intended Use

The Multivolume Pycnometer 1305 is designed to measure rapidly the skeletalvolume of powders, granules, or any other solid objects having low vapor pres-sures and to permit computation of absolute density when weight information issupplied.

It will measure with diminishing effectiveness the volumes of materials whichhave appreciable vapor pressures, i.e., materials which slowly evaporate or subli-mate or are contaminated with such vapors. Materials having extremely high sur-face areas or which absorb appreciable amounts of helium may present somedifficulties and require additional computations or extra measurement steps.

Use both hands when lifting the instrument, one under each side panel.

Observe the following precautions when operating the Model 1305 Pycnometer:

• Unplug the power cord before removing the rear panel to gain access to in-ternal components. Connections carrying potentials as great as 240 V canbe encountered.

• Limit the gas inlet pressure to the 140-170 kPa (20-25 psig) range toavoid possible damage to the instrument. An overpressure relief valve isprovided internally to protect the instrument and operator but it may causeloss of large amounts of helium if the 170 kPa (25 psig) setpoint is ex-ceeded. Exercise standard safety precautions when handling compressedgases.

• Before attempting to open the sample chamber: always close the gas inletvalve, open the vent valve, and wait until the internal pressure falls to lessthan 1.0 psig. Failure to do so may result in powdered samples beingpulled from the sample cup and contaminating the internal spaces of theinstrument or being propelled toward the operator.

• Finely powdered samples may be pulled into the internal components ofthe instrument if excessively high fill or vent flow rates are used, espe-cially if a vacuum is being used. Always begin with the flow rate controlsset at or near minimum when running such samples. Gradually increasethe flows as to achieve adequate but safe rates of pressure change.

• Do not spill abrasive particles between the walls of the 5- and 35-cm3

sample chamber inserts and the sample chamber. The inserts may stick inthe sample chamber or scratch the O-ring sealing surface near the top ofthe sample chamber and cause leaks. Always clean the sample chamberand sample chamber inserts with a clean, soft, lint-free cloth or tissue be-fore loading the sample chamber insert. Avoid scratching or denting thesample chamber or sample chamber inserts or the inserts may fail to fitthe chamber.

Model 1305 MultiVolume Pycnometer Precautions and Intended Use

Jun 99 1-5

Specifications

The Model 1305 MultiVolume Pycnometer has been designed and tested to meetthe specificaitons provided below.

Characteristic Specification

————————— SAMPLE VOLUME —————————

150 cm3 Range:

(indicates 35 to 150 cm3)

Cylindrical sample chamber, 5.080 cm (2.000 in.)diameter x 7.620 cm (3.000 in.) usable depth;allows up to 154.4 cm3 nominal volume. Samplecup measures 4.572 cm (1.800 in.) insidediameter x 7.277 cm (2.865 in.) usable depth,holds up to 119.5 cm3 bulk volume of powder orother material.

35 cm3 Range:

(indicates 5 to 35 cm3)

Sample chamber insert with a cylindrical samplechamber, 3.556 cm (1.400 in.) diameter x 3.556cm (1.400 in.) usable depth; allows up to 35.32cm3 nominal volume. Sample cup measures 3.406cm (1.341 in.) inside diameter x 3.429 cm (1.350in.) usable depth holds up to 31.25 cm3 bulkvolume of powders or other material.

5 cm3 Range:

(indicates less than 5 cm3)

Precision sample chamber insert with acylindrical sample chamber, 1.842 cm (0.725 in.)diameter x 1.842 cm (0.725 in.) usable depth;allows up to 4.905 cm3 nominal volume. Samplecup measures 1.689 cm (0.665 in.) insidediameter x 1.755 cm (0.691 in.) usable depthholds up to 3.933 cm3 bulk volume of powder orother material.

——————— ACCURACY/REPRODUCIBILITY ———————

Depends upon nature of sample. Samples containing water vapor or other vola-tile matter will adversely affect results. Extremely high specific surface areasamples may require a computed correction. Clean, dry samples of medium tolow surface area will run as follows:

150 cm3 Range: ±0.2% (±0.3 cm3) of full scale guaranteed;±0.1% or better usually attained

35 cm3 Range: ±0.2% of full scale (±0.070 cm3) guaranteed;±0.1% (±0.035cm3) usually attained

5 cm3 Range: ±0.2% of full scale (±0.010 cm3)guaranteed.±0.1% (±0.005cm3) usually attained

Specifications Model 1305 MultiVolume Pycnometer

1-6 Jun 99


———————————— THROUGHPUT ————————————

Up to 15 samples per hour when sample preparation not required. Duplicationof measurement requires less than two minutes for sample already in chamber.

—————————— UTILITIES/SUPPLIES ——————————

Accommodates to standard power mains worldwide.

Voltage: 100, 120, 220 or 240 VAC +10%

Current: 0.25 A (100/120 VAC); 0.15 A (220/240 VAC)

Frequency: 50/60 Hz

Gas: Helium at 140 to 170 kPa (20 - 25 psig) forspecified performance. Any other drynoncorrosive gas may be used with reducedaccuracy. Nitrogen is recommended forminimum performance loss if helium isunavailable.

Vacuum: Attachment point for customer-supplied vacuumpump to permit thorough removal of vaporsfrom samples if required.

—————————— EXPOSED MATERIALS ——————————

Sample Cups, Chamber,Inserts, and Caps: Aluminum

O-rings: Buna-N

Tubes, Fittings, etc. Copper and Brass

———————————— ENVIRONMENT ————————————

Temperature: 19.5 - 25 °C (67 - 77 °F) and stable duringruns for specified accuracy without recalibrationon the 5 cm3 range; 10 - 40 °C (50 - 104 °F)and stable during runs for all other ranges orthe 5 cm3 range with calibration at theoperating temperature.

0 - 50 °C (32 - 122 °F); storage and shipping.

Humidity: 20 - 80% (non-condensing)

Model 1305 MultiVolume Pycnometer Specifications

Jun 99 1-7


—————————————— CABINET ——————————————

Physical: 31.1W x 18.7H x 38.1D cm(12.25W x 7.36H x 15.0D in.)

Weight: 7.9 kg (17.4 lbs)

Specifications Model 1305 MultiVolume Pycnometer

1-8 Jun 99

CHAPTER 2

INSTALLATION

• Unpacking and Inspection

• Selecting the Location

• Selecting the Voltage

• Gas Supply

INSTALLATION

This chapter describes how to unpack and inspect the equipment, how to installthe analyzer and the analysis program, and how to verify operation of the ASAP2405 system.

Unpacking and Inspection

When you unpack the shipping cartons, carefully compare the packing list withthe equipment actually received, while checking for equipment damaged duringshipment. Be sure to sift through all packing materials before declaring equip-ment missing.

It is very important to save the shipping cartons when equipment is tobe declared as damaged or lost. The inspector (or claim investigator)must examine the cartons prior to completion of the inspection report.

Equipment Damage or Loss During Shipment

When equipment is damaged or lost in transit, you are required to make note ofthe damage or loss on the freight bill. The carrier, not the shipper, is responsiblefor all damage or loss. In the event of equipment damage or loss during ship-ment, contact the carrier of the equipment immediately.

Equipment Return

Micromeritics strives to ensure that all items arrive safely and in working order.Occasionally, due to circumstances beyond our control, equipment is receivedwhich is not in working condition. When it is necessary to return equipment(damaged either during shipment or while in use) to Micromeritics for repair orreplacement, the following procedure should be followed:

1. Tag or identify the defective equipment, noting the defect and circumstances,if any, under which the defect is observed.

2. Reference the sales order or purchase order, and provide the date that theequipment was received.

3. Notify the Micromeritics Service Department of the defect and request ship-ping instructions. The service department will assign a Returned MaterialsAuthorization (RMA) number. Write the RMA number on the outside of theshipping carton.

Model 1305 MultiVolume Pycnometer Unpacking and Inspection

Jun 99 2-1

Selecting the Location

The Model 1305 Pycnometer performs best in a regulated temperature environ-ment. It should be installed on a workbench 75-90 cm (30-36 in.) high in a loca-tion free of drafts from either a forced-air heating or cooling system. It shouldnot be located near a window where it will be exposed to direct sunlight.

A square meter (10 ft2) of free space to one side and a few centimeters to therear of the instrument should be provided for working space. Ready access to ananalytical balance capable of weighing to 1 mg for sample preparation is advanta-geous. Space near the instrument in which to mount securely the appropriate gascylinder will be necessary if the workbench is not plumbed to supply the gas.

Sharp variations in ambient pressure caused by fans or doors closing rapidly maycause erratic results; avoid these locations.

Selecting the Voltage

All instruments leave the factory set for 120 VAC and with the line fuse re-moved. The correct setting of the universal power entrance must be checked andthe appropriate fuse installed before the Model 1305 can be operated. The Model1305 is designed to operate with either 100, 120, 220 or 240 VAC at 50 or 60Hz. Voltage selection and fusing are made at the power connector which is lo-cated on the right side panel of the unit.

The power cord should be disconnected from the Model 1305 before re-moving the cover from the power input connector. Failure to disconnectthe power cord could result in electrical shock.

1. Make sure the power cord is disconnected from the pycnometer.

2. Using a pointed object, remove the fuse block and cover assembly from thepower connector on the right side of the pycnometer.

Figure 2-1. Removing Fuse Block and Cover Assembly

Selecting the Voltage Model 1305 MultiVolume Pycnometer

2-2 Jun 99

3. Pull the voltage selector card straight out of the power connector housing.

Figure 2-2. Removing Voltage Selector Card

4. Orient the voltage selector card so that the desired voltage is indicated at thebottom. Orient the indicator pin so that it points upward as shown in the fol-lowing illustration.

Figure 2-3. Voltage Selection

5. Insert the voltage selector card into the power connector housing with theedge containing the desired voltage first and with the printed side facing thepower ON/OFF switch.

Figure 2-4. Inserting Voltage Selector Card

Pin

Voltage

Voltage Selector Card

Model 1305 MultiVolume Pycnometer Selecting the Voltage

Jun 99 2-3

6. Fuse the input power line according to local safety practices. The inputpower connector can be used with either a single-fuse arrangement or a dou-ble-fuse arrangement, as shown in the following illustration.

Figure 2-5. Fusing Arrangements

The power cord should be disconnected from the pycnometer wheninstalling or replacing fuses. Failure to do so could result in electricalshock.

a. Observe the position of the fuse block, using the previous figure for ref-erence. If the single-fuse arrangement is desired, position the fuse blockso that the side with the single-fuse slot and the jumper bar is awayfrom the cover.

If the double-fuse arrangement is desired, position the fuse block ssothat the side with the double-fuse slots is away from the cover.

b. If the fuse block is positioned properly for the fusing desired, proceed toStep c.

If the fuse block is not positioned properly for the fusing desired:

1) Remove the fuse block retaining screw.2) Lift the fuse block from the cover.3) Rotate the fuse block.4) Mount the fuse block to the cover.5) Replace the retaining screw.

Fuse

Retaining Screw

Fuse Block

Cover

Jumper Bar

Fuse Block

Fuse Block

Cover

Fuse

Fuses

SINGLE-FUSE DOUBLE-FUSE

Selecting the Voltage Model 1305 MultiVolume Pycnometer

2-4 Jun 99

The fuses used in the pycnometer must be identical in type and rating tothat specified. Use of other fuses could result in electrical shock and/ordamage to the pycnometer.

c. Insert appropriate fuse(s) for the input power source. Refer to the chartbelow for the appropriate fuse rating.

Power Source Fuse

100-120 VAC 0.50 Amp, 3AG, Slow Blow

220-240 VAC 0.25 Amp, 5 x 20 mm Slow Blow, Type T

7. Insert fuse block and cover assembly into input power connector and snap itinto place. Once the fuse block and cover assembly are in place, the positionof the indicator pin shows the input power selected.

Figure 2-6. Inserting Fuse Block and Cover Assembly

Model 1305 MultiVolume Pycnometer Selecting the Voltage

Jun 99 2-5

Gas Supply

The helium or other gas used, whatever its source, should be regulated to a pres-sure between 140 and 170 kPa (20 and 25 psig) by a reliable leak-tested regula-tor. Suitable regulators are available from Micromeritics. Refer to Chapter 5 forordering information. The regulator outlet should be attached with metal tubing tothe MultiVolume Pycnometer 1305 on the righthand side of the instrument to thefitting closest to the power entranc; a roll of copper tubing with fittings is sup-plied in the accessory kit for this purpose.

It is easy to overtighten the fitting that admits analysis gas to the MultivolumePycnometer 1305. Doing so can collapse the copper tubing, damage the fitting,and actually cause a leak. Tighten each nut solidly finger-tight and then add one-quarter turn with a wrench.

Micromeritics uses and recommends the use of research-grade gases. If unobtain-able, the highest purity gas conveniently available will probably prove satisfactory.

Upon first applying gas pressure, verify that no gas flow is occurring when theFILL valve on the front panel of the instrument is closed. Flow may indicate thatthe inlet connection was improperly made or that enough pressure was applied toopen the protective relief valve in the instrument.

Gas Supply Model 1305 MultiVolume Pycnometer

2-6 Jun 99

CHAPTER 3

OPERATION

• Controls and Components

• Startup

• Preparing and Weighing the Sample

• Performing an Analysis

• Calculating the Sample Volume, Density, and Specific Volume

• Verifying Calibration

• Calibrating the Analyzer

• Turning Off the Analyzer

OPERATION

The Multivolume Pycnometer 1305 permits the rapid determination of sample vol-umes. This chapter provides information and instructions to assist you in obtain-ing maximum accuracy and productivity in running samples, calculating results,and ensuring accurate calibration of the instrument.

Controls and Components

Before operating the Model 1305 Pycnometer, you should become familiar withits controls and components. All operating controls for the Model 1305 Pycnome-ter are on the front panel (shown in the following illustration). The gas, vacuum,and power connections are located on the right side panel.

Controls

ON/OFF switch Provides electrical power to the analyzer. Lighting ofthe numbers on the pressure display indicates that ACpower is present.

Model 1305 MultiVolume Pycnometer Controls and Components

Jun 99 3-1

ZERO adjustmentknob

Allows you to zero the pressure reading following theventing of the internal volumes to the atmosphereThis control is a 10-turn precision potentiometer allow-ing you to set the zero to the nearest 0.001 psig witha range of more than ± 0.300 psig.

Before using this adjustment, ensure that:

• the FILL valve is in the CLOSE position• the PREP/TEST valve is in the TEST position• the VENT valve is in the OPEN position• the pressure has stabilized

>5/<5 and >35/<35valves

Allow you to alter the size of the expansion volumeto provide the best match and, therefore, the best reso-lution and sensitivity for each of the 150-, 35-, and 5-cm3 ranges.

• 150-cm3 range: Do not use a sample chamber in-sert. Set the >5/<5 valve to >5 and the >35/<35valve >35. Expansion volumes 1, 2, and 3 are thenconnected together and used as the one largest ex-pansion volume, VEXP150.

• 35-cm3 range: Use the 5.08 cm (2 in.) diameter by7.62 cm (3 in.) height sample chamber insert withthe largest well. Set the >5/<5 valve to >5 and the>35/<35 valve <35. Expansion volumes 1 and 2 arethen connected together and constitute the intermedi-ate expansion volume, VEXP35.

• 5-cm3 range: Use the 5.08 cm (2 in.) diameter by7.62 cm (3 in.) height sample chamber insert withthe smaller well. Set the >5/<5 valve to <5. The po-sition of the >35/<35 valve has no effect, but forconsistency set it to <35. Expansion volume 1alone is then used and is designated VEXP5.

FILL valve Allows you to admit helium or other gases into the in-strument for purging or charging prior to a volumemeasurement.

VENT valve Allows you to open a discharge path for the purgegas, establish the zero psig starting condition in thesample chamber and expansion volume, or open apath to any vacuum applied to the discharge port.

Controls and Components Model 1305 MultiVolume Pycnometer

3-2 Jun 99

FILL RATE control valve

Controls the rate of pressure build when charging thesample chamber or the flow rate when purging a sam-ple during preparation. A judicious balance of the ap-plied pressure (say, 22 psig) along with this settingpermits nearly the same charging pressure to bereached during test, ensuring maximum reproducibil-ity. Turn the valve clockwise to reduce the flow rate;counterclockwise to increase it. A stop will bereached just before flow entirely ceases.

VENT RATE control valve

Controls the rate of flow when the VENT valve issuddenly opened, especially if a vacuum is applied tothe discharge port. Proper setting of this control pre-vents fine powders from being pulled from the sam-ple cup and deposited in the valves and tubing of theinstrument.

Always begin with this control fully clockwise if finepowders are to be measured.

PREP/TEST valve Divides the instrument’s internal volume into twoparts: the sample cell volume and the expansion vol-ume. These two volumes are isolated and the expan-sion volume is sealed when the valve is in the PREPposition. The sample cell may then be charged withgas under pressure without altering the pressure in theexpansion volume.

When placed in the TEST position, the expansion vol-ume is connected to the sample chamber volume anda continuous flow-through path is established to per-mit purging. The resulting pressure then depends uponthe volume ratios and initial pressures in the spaces.


Jun 99 3-3

Components

Pressure display Displays the current pressure with a range of 0.0 to19.999 psig. The calibration is not exact as the mostimportant consideration is linearity rather than abso-lute accuracy.

Sample chamber The sample chamber is made of stainless steel andcontains gas inlet and outlet holes to permit a flow-through path for ease of purging. A 5.08-cm (2-in.) di-ameter and 7.62-cm (3-in.) depth (cap in place)results in a volume of somewhat over 154 cm3. Pow-dered samples placed directly in the chamber wouldobviously clog the outlet tubing and would be diffi-cult to recover from the chamber. A light-gauge re-movable sample cup is provided to permit easyhandling of samples. This cup reduces the sample ca-pacity for powders to about 120 cm3 since it must besmaller than the chamber diameter.

Sample chamberinsert

Accuracy of the MultiVolume Pycnometer 1305 tendsto be a fixed fraction of the maximum sample cham-ber volume whether filled with sample or not. Samplechamber inserts are provided to create chambers of 35-and 5-cm3 nominal volumes so that small samples canbe run with high resolution and accuracy. These sam-ple chamber inserts, especially the 5-cm3 one, arehigh precision parts in the form of cylinders approxi-mately 5.08 cm (2 in.) in diameter and 7.62 cm (3 in.) in length. Cylindrical wells are machined inthe upper faces to create the sample chambers.Enough clearance is left between the sample chamberwall to permit free flow of the gas during purging.

Sample cups Light-gauge removable sample cups also made of alu-minum are provided to fit closely in the machinedwells in the top of the sample chamber inserts. Thesewill hold bulk volumes of 31.25 cm3 and 3.933 cm3

for the 35-cm3 nominal range and 5-cm3 nominalrange, respectively.

A bent end probe is provided to facilitate easy re-moval of the sample cups. This probe is to be used inconjunction with small holes in the upper lip of thesample cups to lift the cup to a point where it can begrasped by fingers.


3-4 Jun 99

Calibration Volume Four precision balls (volumes) are supplied with theinstrument to be used as high accuracy calibrationstandards.

• one 2.4250-cm3 ball of 0.6563-in. diameter for usewith the 5-cm3 sample volume range

• one 16.758-cm3 ball of 1.2500-in. diameter for usewith the 35-cm3 range

• two 25.49-cm3 balls (50.97-cm3 total) of 1.4375-in.diameter for use with the 150-cm3 range.

These volumes should be kept clean and maintainedas near the temperature of the instrument as possiblewhile in use.

Sample Chamber Capand Sealing O-ring

Permits opening and closing of the sample chamberwith volume variations held to the microliter or lessrange. The flat surface of the sealing plug mates witha matching flat of the lip of the sample cup to pro-vide a precise metal-to-metal stop. These surfacesmust be kept scrupulously free of particles, especiallywith the 5-cm3 range, if the best instrument perform-ance is to be achieved. The sealing plug is fitted witha 2 x 1-7/8 x 1/16-in. Buna-NTM o-ring which makesthe seal. This o-ring should be coated with a thinlayer of vacuum grease. It and all the surfaces ittouches or wipes must be maintained free of particles.Two spare o-rings are included in the accessory kit.

Pressure transducer The pressure transducer is a 25-psig unit of ±0.1% offull scale accuracy. It is used only up to 20 psig inthe instrument. It will indicate vacuum down to about-5 psig before showing a constant reading. Eventhough it will not indicate vacuum below -5 psig, it isnot harmed by application of high vacuums. It is lo-cated in the electronics enclosure on the other side ofthe wall from the filter assembly. This transducer typehas been chosen for its excellent linearity, a factor es-sential to the accurate operation of the Model 1305MultiVolume Pycnometer.


Jun 99 3-5

Overpressure ReliefValve

Provided for protection against damage to the instru-ment. The overpressure relief valve is connected di-rectly at the gas input connection and is set at thefactory to open when the pressure reaches 25 ±1 psig.The setting is altered by means of a set screw at itsdischarge end. The setting should be changed only ifan accurate pressure gauge is available and the reliefpoint is known to be incorrect. Resealing of thisvalve requires that the gas inlet pressure be reducedto under 20 psig before leaking will stop.

Filter The filter is a large area, fritted metal disk installedjust downstream of the sample chamber. Its functionis to protect the transducer, valves, and expansion vol-umes against contamination by powder particleswhich could cause leaks, volume changes, and pres-sure instability. It is mounted on the rear wall of theplumbing compartment in a cylindrical assembly. Thefilter should be cleaned or replaced only after confirm-ing that powder has been drawn into the system. Aspare filter is included in the accessory kit.

Gas inlet and Gas outlet/vacuumconnection

The gas inlet is a 1/4-in. diameter threaded brass con-nection designed to accept 1/8-in. metal tubing se-cured by a Swagelok® fitting with brass ferrules.

The gas outlet/vacuum connection is a 0.300-in. di-ameter brass barbed fitting intended for use with0.250-in. inside diameter rubber or plastic tub-ing. Both fittings are located on the righthand side ofthe instrument near the power entrance. The gas out-let/vacuum connection is closest to the front of the in-strument.

Power entrance Power enters the instrument through this assembly lo-cated on the righthand side of the instrument. An inter-national power connector of the IEC-type is includedand requires a detachable power cord which is in-cluded in the accessory kit.

A small circuit card permits selection of any operatingvoltage. A built-in fuse provides protection; the fuseshould be a 0.5 Ampere slow-blow type for voltagesof 100 to 120 volts and a 0.25 Ampere slow-blowtype for 200 to 240 volts. Refer to Chapter 2 for in-structions on voltage selection and fusing.


3-6 Jun 99

DC power supply The DC power supply is located in the electronicscompartment and is accessible by removing the rearpanel (detach power cord first). It is a standard OEMopen-frame unit wired to deliver +24 VDC and +5VDC to power the transducer and pressure display, re-spectively.


Jun 99 3-7

Startup

The following procedure should be followed when the Multivolume Pycnometer1305:

• is being used for the first time• has not been used for several days

Before beginning this procedure, ensure that the gas supply has been con-nected and that the proper voltage is being supplied to the analyzer. (Re-fer to Chapter 2 for voltage requirements.)

1. Turn on the analyzer and observe that the pressure display illuminates.

2. Remove the sample chamber cap and inspect the chamber; clean the cham-ber if particles or powders are present.

3. Using a clean, lint-free cloth or tissue, wipe the upper rim and the upper in-side surface of the chamber to remove any particles or buildup of greasefrom the O-ring.

4. Inspect the bottom of the sample chamber cap; clean the sealing plug and itsflat surface.

5. Ensure that the O-ring is undamaged and that the grease film is clean andadequate. If in doubt about either, replace them.

6. Install the desired sample chamber insert as follows:

Be sure the insert is clean; use a lint-free cloth if cleaning is required.

If you are using the 150-cm3 range, an insert is not required. If the cham-ber is empty, proceed to step 8. If an insert is in the chamber, proceed tostep 7 for instructions on removing it.

a. Place the VENT valve in the OPEN position, then turn the VENT RATEcontrol knob several turns counterclockwise to open it.

b. Place the insert into the sample chamber; a gentle push may be used ifneeded. Be sure the insert is properly aligned with the sample chamberbefore pushing.

c. Proceed to step 8.

Startup Model 1305 MultiVolume Pycnometer

3-8 Jun 99

7. If analysis is to be performed in the 150-cm3 range and an insert is in thechamber, perform the following steps to remove it:

a. Place the VENT valve in the OPEN position, then turn the VENT RATEcontrol several turns counterclockwise to open it.

b. Place the FILL valve in the OPEN position. This allows the gas pressureto ease the insert up gently until it can be grasped. Do not force the in-sert to move rapidly; it will come out easily if allowed a few seconds.

8. Ensure that the FILL valve is in the CLOSE position.

9. Place the PREP/TEST valve in the TEST position.

10. Place the >5/<5 valve in the >5 position and the >35/<35 valve in the >35position.

11. Ensure that the VENT valve is in the OPEN position.

12. Replace the sample chamber cap.

13. Place the FILL valve in the OPEN position. Allow gas to flow through theinstrument for approximately five minutes. Use a mid-range setting on theFILL RATE and VENT RATE valves.

14. Place the FILL valve in the CLOSED position; wait until the pressure read-ing falls and becomes stable.

15. Adjust the ZERO control to indicate +0.000.

16. Place the valve in the position appropriate for the sample volume range (andinsert) you plan to use (refer to the following illustration):

• Under 5 cm3, place the >5/<5 valve in the <5 position and the >35/<35valve in the <35 position

• 5 to 35 range, place the >5/<5 valve in the >5 position and the >35/<35valve in the <35 position

• 35 to 150 range, place the >5/<5 valve in the >5 position and the>35/<35 valve in the >35 position

Model 1305 MultiVolume Pycnometer Startup

Jun 99 3-9

Figure 3-1. Pycnometer Settings for Optimum Results

17. Place the PREP/TEST valve in the PREP position.

The instrument is now ready to run samples.

Nominal SampleVolume (cm3)

Insert in SampleChamber Valve Orientation

Under 5

5 to 35

35 to 150

Startup Model 1305 MultiVolume Pycnometer

3-10 Jun 99

Preparing and Weighing the Sample

Sample preparation consists of:

• obtaining a representative sample of the material

• removing any vapors (especially water) which would interfere with thepressure ratios measured by the instrument

• placing it in an appropriate sample cup

Weighing of the sample is required if density or specific volume is to be com-puted. This is best done after vapor removal and most often should be done afterrunning the sample. Weighing and recording the weight of the empty sample cupwill permit the net weight of the filled sample cup to be calculated later.

Porous samples which trap helium may cause buoyancy and weight drift so careshould be exercised to purge porous samples thoroughly with dry air or nitrogenif the highest degree of accuracy is required.

Model 1305 MultiVolume Pycnometer Preparing and Weighing the Sample

Jun 99 3-11

Performing an Analysis

The following step-by-step procedure assumes that the >5/<5 valve and the>35/<35 valve have been set to the desired range, that the matching insert is inplace or available, and that the matching sample cup contains the sample to beanalyzed. Appendix B contains a sample data sheet for organizing and recordingdata.

1. Ensure that the FILL valve is in the CLOSE position.

2. Place the PREP/TEST valve in the PREP position.

3. Ensure that the VENT valve is in the OPEN position.

4. Remove the sample chamber cap.

5. Remove any previous sample and/or insert and cup.

6. Place the new sample and/or insert into the chamber.

7. Replace the sample chamber cap; securely tighten.

8. Close the VENT RATE and FLOW RATE valves.

9. Place the FILL valve in the OPEN position.

10. Open the VENT RATE and FLOW RATE valves to approximately mid-range.

If your sample is a light powder, open the valve slowly to avoid splashingof the powder.

11. Air and vapors trapped within pores, crevices, or among the pieces of thesample will be removed from the sample by a prolonged purge in this condi-tion. However, these gases are much more rapidly removed by alternately in-creasing and decreasing the gas pressure in the sample chamber. Place theVENT valve in the CLOSE position and allow the pressure to rise.

12. When the indicated pressure has risen to, say, 16 to 18 psi, close the FILLvalve and open the VENT valve. When the indicated pressure then drops to,say, 1 to 0.5 psi, close the VENT valve and open the FILL valve. Repeatingthis procedure 8 or 10 times adequately purges from most powdered or po-rous samples whatever gases they originally entrained and replaces themwith the “working” gas, i.e., the helium or dry nitrogen.

13. Place the FILL valve in the CLOSE position and the VENT valve in theOPEN position.

Performing an Analysis Model 1305 MultiVolume Pycnometer

3-12 Jun 99

14. Place the PREP/TEST valve in the TEST position.

15. Allow the pressure to fall to zero and stabilize, correcting the pressure dis-play with the ZERO control as necessary.

16. Place the PREP/TEST valve in the PREP position, ensuring that the zerodoes not shift. If a shift occurs, return the valve to the TEST position and re-peat Step 15.

17. Place the VENT valve in the CLOSE position, disregard any change ofpressure.

18. Place the FILL valve in the OPEN position and fill the chamber to 19.500±0.200 psig as shown on the pressure indicator.

19. Place the FILL valve in the CLOSE position and allow the pressure to equili-brate; record it as P1. Short times (approximately 15-30 sec) give best resultsfor most samples.

20. Immediately place the PREP/TEST valve in the TEST position and allow thepressure to equilibrate; record it as P2. Short times (approximately 15-30sec) give best results for most samples.

21. Place the VENT valve in the OPEN position. If light powders are being ana-lyzed, first close the VENT RATE valve (turn counterclockwise); then gradu-ally open it as the pressure approaches zero.

22. Return to Step 15 if multiple determinations are to be made on this sample.

23. Remove the sample cup using the bent-end probe provided in the accessorykit. Hook the probe in the hole in the upper lip of the cup and pull upwarduntil the cup can be grasped with fingers.

• If a new sample is to be analyzed, return to Preparing and Weighing theSample.

• If the instrument is to remain idle for an extended period (days), close thesample chamber and shut off the helium supply. Refer to Turning Off theAnalyzer in this chapter for the proper shutdown procedure.

When all samples have been run, proceed to the next section for instructions oncalculating the results from the pressures recorded.

Model 1305 MultiVolume Pycnometer Performing an Analysis

Jun 99 3-13

Calculating the Sample Volume, Density, and Specific Volume

The general equation for computing the sample volume is

VSAMP = VCELL − VEXP

P1 ⁄ P2 − 1

where

VSAMP = the sample volume to be found,

VCELL = the empty volume of the sample cell with the empty sample cup in place,

VEXP = the expansion volume added when the PREP/TEST valve is in the TEST position,

P1 = the charge pressure (recorded in Step 18 of Performing an Analysis, and

P2 = the pressure after expansion (recorded in Step 19 of Performing an Analysis.

Each range has its values for VCELL and VEXP; these are provided on the calibra-tion sheet for the instrument. Numerical suffixes are added to each to identify therange to which they pertain; for example, VEXP35 is the expansion volume usedon the 35-cm3 range.

A sample data sheet to help facilitate computations is included in Appendix B. Adetailed derivation of the equation is found in Appendix A. The computer pro-gram in Appendix C may be used to automate sample computation.

Density is defined as the weight per unit volume and will usually be computed as

ρSAMP = WSAMP

VSAMP =

Gross Weight − Cup WeightVSAMP

where

ρSAMP = sample density,

WSAMP = sample weight, and

VSAMP = sample volume.

Calculating the Sample Volume, Density, and Specific Volume Model 1305 MultiVolume Pycnometer

3-14 Jun 99

Specific volume is defined as the volume per unit weight and is computed as

USAMP = VSAMP

WSAMP =

1ρSAMP

where

USAMP = sample specific volume.

Verifying Calibration

Two quick checks may be made to determine if the instrument needs to be recali-brated.

• the zero offset or additive errors of the instrument • the scale factor errors (assuming that the zero offset errors are negligible)

These checks should be made if changes have occurred in the inner parts of theinstrument, the sample chamber or cap, the sample inserts, the sample cups, or ifthe temperature differs appreciably from the temperature at the time of the pre-vious calibration.

Zero Offset

Verify the zero offset by running the empty sample cup and calculating the re-sult. The error from zero should be less than 0.2% of the full scale range.

Scale Factor

Verify the scale factor by placing the calibration volumes (balls) in the samplecup and running them as if they were samples and computing the results. The vol-ume error from the values supplied on the calibration data sheet should be lessthan 0.2% of the full scale range. The calibration data sheet and the calibratedvolumes are supplied in the accessory package and are designated as VCALIB withnumerical suffixes to indicate the range.

If excessive errors are revealed during verification, perform the calibration proce-dure in the following section to establish new, accurate values for the VCELL andVEXP instrument constants.

Model 1305 MultiVolume Pycnometer Verifying Calibration

Jun 99 3-15

Calibrating the Analyzer

Definition of Volumes to be Calibrated

Illustrated here is a schematic diagram of the Multivolume Pycnometer 1305 withlabels added to facilitate the discussion which follows. Refer to it as the follow-ing is read.

Figure 3-2. Schematic of 1305 MultiVolume Pycnometer

Operation of the instrument depends upon first charging the volume between theFILL valve and the VENT valve (VSAMP) to an elevated gas pressure (P1), thenrotating the PREP/TEST valve to expand the pressure into a precisely knownadded volume (VEXP). The final pressure (P2) then is indicative of the sample vol-ume since larger sample volumes reduce by displacement the amount of gas inthe initial charge and result in lower final pressures.

Calibrating the Analyzer Model 1305 MultiVolume Pycnometer

3-16 Jun 99

The following six calibrated volumes must be known for each instrument beforesample runs can be made:

VCELL5 The sample cell and void volume between the FILL valve and theVENT valve when the PREP/TEST valve is in the PREP position,the 5-cm3 sample chamber insert is in place, and the empty 5-cm3

sample cup is in place.

VCELL35 The sample cell and void volume between the FILL valve and theVENT valve when the PREP/TEST valve is in the PREP position,the 35-cm3 sample chamber insert is in place, and the empty 35-cm3

sample cup is in place.

VCELL150 The sample cell and void volume between the FILL valve and theVENT valve when the PREP/TEST valve is in the PREP positionand the empty 150-cm3 sample cup is in place.

VEXP5 The volume added to VCELL5 when the PREP/TEST valve is in theTEST position while the >5/<5 valve is in the <5 position.

VEXP35 The volume added to VCELL35 when the PREP/TEST valve is rotatedto TEST while the >5/<5 valve is in the >5 position and the>35/<35 valve is in the <35 position.

VEXP150 The volume added to VCELL150 when the PREP/TEST valve is in theTEST position while the >5/<5 valve is in the >5 position and the>35/<35 valve is in the >35 position.

The instrument is always calibrated on each range using a standard volume, pref-erably the precision ball bearing which fills the maximum possible fraction of thesample cup. The labels VCALIB5, VCALIB35, and VCALIB150 will be used to identifythese. When using the precision ball bearings provided with the instrument:

VCALIB5 = 2.4250 cm3; VCALIB35 = 16.758 cm3; and VCALIB50 = 2 x 25.49 cm3 = 50.97 cm3

Sample volumes will be labeled VSAMP. The pressure to which the system is in-itially charged will always be P1 and the pressure after expansion will always beP2. Asterisks or other symbols may be added to differentiate P1, P2 pairs takenwith differing sample chamber contents. A detailed derivation of the calibrationtheory and equations is presented in Appendix D.

Model 1305 MultiVolume Pycnometer Calibrating the Analyzer

Jun 99 3-17

Calibration Procedure

This procedure measures VCELL5, VCELL35, VCELL150, VEXP5, VEXP35, and VEXP150

as the average of three repeated determinations. A data sheet is provided in Ap-pendix B from which results can be computed by using the calculator worksheealso provided in Appendix B.

This procedure must be used on all new instruments; or after any changes to thesample chamber, tubing, fittings, sample cup or sample chamber inserts have oc-curred which might alter their volumes, and whenever the operating temperaturediffers appreciably from the nominal 72 oF calibration temperature.

When the following steps call for a “sample run,” perform the steps outlined inPerforming an Analysis (located in a previous section of this chapter).

1. Connect electrical power to the instrument and allow it to begin a 15-minutewarmup.

2. Place the three empty sample container cups, all the VCALIB standard vol-umes, and the two sample chamber inserts alongside the instrument to ther-mally equilibrate. Wipe them with a lint-free cloth or tissue to removeparticles or oils.

3. Connect helium regulated at 138 to 152 kPa (20-22 psig) to the helium inlet(threaded fitting nearest the back of the instrument on the righthand side).

4. Place the >5/<5 valve in the <5 position.

5. Place the >35/<35 valve in the <35 position.

6. Install the 5-cm3 chamber insert and place the empty 5-cm3 sample cup in it.Make three sample runs and record the pressures in the appropriate place ona copy of the data sheet in Appendix B.

7. Place the VCALIB5 standard volume in the 5-cm3 sample cup and make threesample runs. Record the VCALIB5 and pressures on the data sheet.

8. Place the >5/<5 valve in the >5 position and the >35/<35 valve in the <35position.

9 Install the 35-cm3 chamber insert and place the empty 35- cm3 sample cupin it. Make three sample runs and record the pressures on the data sheet.

10. Place the VCALIB35 standard volume in the 35-cm3 sample cup and makethree sample runs. Record the VCALIB35 and pressures on the data sheet.


Calibrating the Analyzer Model 1305 MultiVolume Pycnometer

3-18 Jun 99

12. Remove the 35-cm3 sample chamber insert and cup, then install the empty150-cm3 sample cup. Make three sample runs; record the pressures on thedata sheet.

13. Place the VCALIB150 standard volume in the 150-cm3 sample cup and makethree sample runs. Record the VCALIB150 and the pressures on the data sheet.

14. Use a hand calculator to calculate the internal volumes or the calculatorworksheet provided in Appendix B. Record the volumes on the data sheetalong with the instrument serial number, the date, and the name of theoperator.

Turning Off the Analyzer

Perform the following steps to properly shut down the Model 1305 Pycnometer:

1. Remove any sample from the sample chamber and replace the sample cap.


3. Place the VENT valve in the OPEN position.

4. Admit helium or other dry gas by opening the FILL valve; purge for at leastone minute. Then placee the FILL valve and the VENT valve in the CLOSEposition.

5. Turn off the power switch if the instrument will not be needed within thenext 24 hours.

6. Close the tank valve or other main supply valve for the gas to avoid lossshould the tubing accidentally be ruptured.

The instrument can be left in this state indefinitely and still be ready to run sam-ples in minutes after restart.

Model 1305 MultiVolume Pycnometer Turning Off the Analyzer

Jun 99 3-19

CHAPTER 4

TROUBLESHOOTING

• Unstable Pressures

• Nonreproducible Results

• Incorrect Results

• Pressure Indicator

• Slow Return to Zero Pressure Upon Venting

TROUBLESHOOTING

Perform the checks and tests described in this section before seeking further assis-tance. Contact your local service representative or the factory when unsuccessfulin resolving the difficulty.

Unstable Pressures

Falling Pressures

Falling temperatures or rising ambient pressure can cause the indicated pressureto continue to fall beyond the expected transients following filling and expansion.The effects are usually minor in a comfortable room and under normal ventilationconditions due to the speed with which sample runs are accomplished.

The most serious cause of falling pressures is a leak. The first leak check shouldbe that of the sample cap O-ring and the sample chamber surface against whichit seals. Inspect the O-ring to determine whether it is damaged; replace it if neces-sary. Clean the sealing surfaces and lightly grease the O-ring with vacuum grease.

To isolate system leaks:

1. Place the PREP/TEST valve in the PREP position, the >5/<5 valve in the <5position, and the >35/<35 valve in the <35 position.

2. Close the VENT valve.

3. Open the FILL valve. Allow the pressure to increase to approximately19.500 psig, then close the FILL valve.

If the pressure remains stable, no leak exists in the sample chamber and asso-ciated tubing and components.

4. Place the PREP/TEST valve in the TEST position

If the pressure remains steady, no leaks exist in the VEXP5 volume or associ-ated positions.

5. Place the >5/<5 valve in the >5 position; observe the pressure stability.

If the pressure remains steady, no leaks exist in the volumes and tubing be-tween the >5/<5 and the >35/<35 valves.

6. Place the >35/<35 valve in the >35 position.

If the pressure remains steady, no leak exists in the largest increment of ex-pansion volume.

Model 1305 Multivolume Pycnometer Unstable Pressures

Jun 99 4-1

Many samples such as organic materials or closed cell foam plastics allow heliumor other gases in the initial gas charge to slowly diffuse into the interior of thesample. To determine whether the sample is responsible for any discrepancy, re-move the sample and re-test with the chamber empty. While some such samplesmay be run and useful information produced, they may require the developmentof special procedures.

Samples colder than the instrument, especially those that are massive or non-po-rous can cause falling pressures. Always try to store samples in the vicinity ofthe instrument for a time sufficient to produce thermal equilibration before testing.

Rising Pressures

Pressures which rise after initial charging with gas are most frequently caused bythe presence of condensible vapors (usually water) on the sample. Continued purg-ing of the sample, vacuum treatment, or repeated runs usually clear up this prob-lem for most samples.

A leak through the FILL valve may cause rising pressures. Removal of inlet pres-sure would then cause the direction of the leak to reverse, confirming the source.

Samples warmer than the instrument, especially those that are massive or non-po-rous, can cause rising pressures until temperature equilibration takes place. Al-ways try to store samples near the instrument for a sufficient period of time toallow thermal equilibration.

Nonreproducible Results

Unstable pressures are the most common cause of lack of reproducibility. Pres-sures should stabilize to better than 0.005 psig per minute before readings aretaken if the specified accuracy is to be achieved. Refer to the previous sectionsfor assistance in stabilizing pressures.

Timing of pressure readings is important. The charging pressure, P1 should be re-corded just before the PREP/TEST valve is placed in the TEST position. The ex-pansion pressure, P2 should be recorded as soon afterward as the pressure hasstabilized; should it not stabilize within 30 seconds, some difficulty exists.

Particles on the rim of the sample chamber or on the mating surface of the cham-ber cap cause a volume change of the chamber and a corresponding error in thesample result. Inspect to be sure that firm metal-to-metal contact is being made,and that the cap has been fully seated.

Nonreproducible Results Model 1305 Multivolume Pycnometer

4-2 Jun 99

Purging is important to remove all air following opening and reclosing of the sam-ple chamber. Air, especially moist air, behaves differently than helium or dry ni-trogen and will cause the sample results to vary.

Zeroing must be done with care and accomplished as shortly before chargingwith gas pressure as feasible. There is some difference between +0.000 and-0.000; one or the other should be used consistently where absolutely best resultsare sought.

Heat and moisture from the hands can cause significant effects. Use gloves or acloth when handling the sample cap and samples to help minimize these effects.

Using charging pressures, P1 outside the 19.500 ±0.200 psig range will causesmall but systematic variations in results due to the small amount of unavoidablenon-linearity in the pressure transducer.

Incorrect Results

Consistent, but incorrect measured volumes may be due to one or more of the fol-lowing causes.

The >5/<5 valve or the >35/<35 valves are in the wrong position for the range inuse, or an incorrect sample chamber insert is being used. Refer to Chapter 3 forinformation on valve positions and inserts.

Operation outside the 67-77 °F range on the 5-cm3 full-scale range may requirerecalibration at the new temperature. Refer to Calibrating the Analyzer in Chap-ter 3.

The calibration may be invalid due to disassembly of tubing, alteration of samplecups, exchange of sample cups or sample chamber inserts, or not using samplecups when the instrument calibration was made with them in place. A samplechamber cap which has changed in its seating will alter the calibration. Particleson the sample chamber floor can cause the sample chamber inserts to protrudeand strike the cap, altering the seating, and causing errors. Refer to Calibratingthe Analyzer in Chapter 3 for instructions on checking and correcting the calibra-tion.

Review carefully the computation of sample results and calibra tion constants toensure that errors are not being made. Confirm the correctness of calibration vol-ume standards through measurements or other independent tests.

Use of charging pressure, P1 differing from the 19.500 ±0.200 psig will require re-calibration to compensate for any slight nonlinearity of the pressure transducer.

Model 1305 Multivolume Pycnometer Incorrect Results

Jun 99 4-3

Samples of high specific surface area may contribute an error due to a layer nearthe surface that is partly depleted of gas molecules termed the annulus volume.Volume errors in the range of 0.005 cm3/g for powders with specific surfaceareas of the order of 100 m2/g or 0.05 cm3/g for 1000 m2/g specific surface areapowders are possible. The user is advised to undertake a special examination ofthis phenomenon so that precise computations may be made for the gas and pow-der system in use.

Use of gases other than helium will lead to somewhat less accurate results. Drynitrogen is usually satisfactory but, in general, the higher the liquefaction tempera-ture and the larger the molecular weight of a gas, the poorer the accuracy sincenonideal behavior becomes more pronounced.

Pressure Indicator

Fails to Illuminate

Verify that the power cord is plugged into an energized outlet of the proper volt-age and firmly seated in the power entrance connector of the instrument. Operatethe power switch to the ON position. Unplug the power cord from the instrumentand remove the fuse and inspect it. If these measures do not reveal the source ofthe problem, again unplug the power cord and remove the rear panel of the instru-ment and inspect the connectors inside to determine if any have loosened. Con-tact your local service representative in the problem persists.

Constantly Indicates Nearly the Same Pressure

During evacuation of samples, the pressure transducer will be internally limited toan indication of about 1/3 of the positive full-scale range or about -5.000 psigeven though the reading should be -14.700 psig. Although the transducer was in-tended for positive pressure indications, this will cause no harm to it.

A reading which does not respond to the FILL valve or VENT valve operationmost likely indicates a defective pressure transducer, pressure indicator, or powersupply. Contact your local service representative for resolution.

Pressure Indicator Model 1305 Multivolume Pycnometer

4-4 Jun 99

Slow Return to Zero Pressure Upon Venting

The VENT RATE control may be set too far clockwise. Increase the flow rate byturning it counterclockwise one or more turns.

Some samples such as organics and plastic foams may trap gas and slowly re-lease it when the pressure is reduced. Remove the sample or permit it to evacu-ate long enough for the trapped gases to diffuse out.

Powders drawn into the internal spaces of the instrument may clog the filter lo-cated on the rear wall of the mechanical section. Clean or replace this filter. Un-plug the instrument and turn off the gas supply before removing any panels.

Model 1305 Multivolume Pycnometer Slow Return to Zero Pressure Upon Venting

Jun 99 4-5

CHAPTER 5

ORDERING INFORMATION

ORDERING INFORMATION

Accessories for the Model 1305 MultiVolume Pycnoemter can be ordered throughour Customer Order Entry Department, (707) 662-3636. Please use the informa-tion provided below.

Part Number Description

004-16006-00 Vacuum grease, 25 grams

003-51135-00 Fuse, 3 AG, 0.5 A, Slow-Blow, for 100/120 V mains

003-51141-00 Fuse, 3 AG, 0.25 A, Slow-Blow, for 200/240 V mains

004-25549-00 Reducer, 1/8-in. (0.32-cm) compression fitting to 1/4-in.(0.64-cm) tube

004-25078-00 O-ring, Buna-N, for sample chamber cap

004-27039-00 Gasket, filter

004-25103-00 Ferrule (front), Teflon, for 1/4-in. (0.64-cm) OD tubing

004-25104-00 Ferrule (rear), Nylon, for 1/4-in. (0.64-cm) OD tubing

004-25198-00 Ferrule (front), brass, for 1/8-in (0-32-cm) OD tubing

004-25199-00 Ferrule (rear), brass, for 1/8-in. (0.32-cm) OD tubing

135-25805-00 Sample cup, 5 cm3

135-25804-00 Sample cup, 35 cm3

135-25812-00 Sample cup, 150 cm3

135-25803-00 Insert, for 5-cm3 sample cup

135-25802-00 Insert, for 35-cm3 sample cup

135-25813-00 Calibration volume, 2.43 cm3



004-62230-58 Gas regulator, CGA 580 fitting, 0-30 psig

004-33601-00 Expansion kit; adds an additional outlet to the gasregulator

135-42802-00 Operator’s manual

Model 1305 MultiVolume Pycnometer Ordering Information

Mar 01 5-1

APPENDIX A

THEORY

THEORY

The Multivolume Pycnometer 1305 is a gas displacement pycnometer, a type ofinstrument which measures the volume of solid objects of irregular or regularshape whether powdered or in one piece. A greatly simplified diagram of the in-strument is shown in Figure A1-1.

Assume that both VCELL and VEXP are at ambient pressure Pa, are at ambienttemperature Ta, and that the valve is then closed. VCELL is then charged to an ele-vated pressure P1. The mass balance equation across the sample cell, VCELL is

P1 (VCELL - VSAMP) = nCRTa (1)

where

nC = the number of moles of gas in the sample cell,

R = the gas constant, and

Ta = the ambient temperature.

Figure A1-1. Simplified Block Diagram of MultiVolume Pycnometer 1305

The mass equation for the expansion volume is

PaVEXP = nERTa . (2)

where

nE = the number of moles of gas in the expansion volume.

Model 1305 MultiVolume Pycnometer Appendix A

Jun 99 A-1

When the valve is opened, the pressure will fall to an intermediate value, P2, andthe mass balance equation becomes

P2 (VCELL - VSAMP + VEXP) = nCRTa + nERTa (3)

Substituting from equations (1) and (2) into (3):

Pn (VCELL - VSAMP + VEXP) = P1 (VCELL - VSAMP) + PaVEXP (4)

or

(P2 - P1)(VCELL - VSAMP) = (Pa - P2)VEXP (5)

then

VCELL − VSAMP = Pa − P2

P2 − P1 VEXP (6)

Adding and subtracting Pa in the denominator and rearranging gives

−VSAMP = −VCELL + (Pa − P2) VEXP

(P2 − Pa) − (P1 − Pa)(7)

Dividing by (Pa - P2) in both the numerator and denominator


−1 −

P1 − Pa

Pa − P2

(8)

or


P1 − Pa

P2 − Pa

− 1

(9)

Since P1, P2, and Pa are expressed in equations (1) through (9) as absolute pres-sures and equation (9) is arranged so that Pa is subtracted from both P1 and P2before use, new P1g and P2g may be redefined as gauge pressures

Appendix A Model 1305 MultiVolume Pycnometer

A-2 Jun 99

P1g = P1 - Pa (10)

P2g = P2 - Pa (11)

and equation (9) rewritten as


P1g

P2g −1

(12)

Equation (12) then becomes the working equation for the MultiVolume Pycnome-ter 1305. Calibration procedures are provided to determine VCELL and VEXP andthe pressures are measured by a gauge pressure transducer. Provisions are madefor conveniently charging and discharging gases at controlled rates, for optimizingthe relative sizes of the sample chambers and expansion volumes, and for cleans-ing the samples of vapors which would render equations (1), (2), and (3) inade-quate to describe the pressure behavior.

Model 1305 MultiVolume Pycnometer Appendix A

Jun 99 A-3

APPENDIX B

FORMS

MultiVolume Pycnometer 1305 Sample Data Sheet

Sample Identification: __________________________________________________________________

____________________________________________________________________________________

Gross Weight: ______________ Full Scale Range: ______________

Cup Weight: ______________ Minutes Purge: ______________

Net Weight: ______________ Minutes Vacuum: ______________

VCELL: ______________ VEXP: ______________


P1

P2 − 1

P1 P2 VSAMP

1. ______________ _______________ _______________

2. ______________ _______________ _______________

3. ______________ _______________ _______________

4. ______________ _______________ _______________

5. ______________ _______________ _______________

6. ______________ _______________ _______________

7. ______________ _______________ _______________

8. ______________ _______________ _______________

9. ______________ _______________ _______________

10. ______________ _______________ _______________

VSAMP Sum _______________

VSAMP Average _______________

Density = Net Weight

VSAMP Average_______________

Page 1 of 1

Data Sheet for Internal Volume CalibrationMultiVolume Pycnometer 1305

Pressures = psig; Volumes = cm3

5-cm3 Range

(empty sample cup) (VCALIB5 in place)

1 P1 ____________ P2 ___________ P1 _________________ P2 ____________

2 P1 _________________ P2 ___________ P1 ___________ P2 ____________

3 P1 _________________ P2 ___________ P1 ___________ P2 ____________

VCALIB5 = _______________

Computed Results from Above Data: VCELL5 = _______________ VEXP5 = _______________

35-cm3 Range


1 P1 ____________ P2 ___________ P1 _________________ P2 ____________

2 P1 _________________ P2 ___________ P1 ___________ P2 ____________

3 P1 _________________ P2 ___________ P1 ___________ P2 ____________

VCALIB35 = _______________


150-cm3 Range


1 P1 ____________ P2 ___________ P1 _________________ P2 ____________

2 P1 _________________ P2 ___________ P1 ___________ P2 ____________

3 P1 _________________ P2 ___________ P1 ___________ P2 ____________

VCALIB150 = _______________


S/N:____________________ Date Calibrated:____________________

Technician:__________________________________________________

Page 1 of 1

MultiPycnometer 1305 Calibration Worksheet for Calculator

Page 1 of 1

APPENDIX C

SAMPLE RESULTS COMPUTATIONPROGRAM

SAMPLE RESULTS COMPUTATION PROGRAM

Model 1305 MultiVolume Pycnometer Appendix C

Jun 99 C-1

APPENDIX D

DERIVATION OF CALIBRATION EQUATIONS

DERIVATION OF CALIBRATION EQUATIONS

Prior to running samples on the MultiVolume Pycnometer 1305, the volume ofthe sample cell and the expansion volume must be known. The derivation that fol-lows permits these internal volumes to be measured with respect to a removable,accurately known standard volume. A simplified diagram of the instrument isshown below.

Assume that, VCALIB is removed, VCELL is charged to an elevated gauge pressureP1 and VEXP is at zero gauge (ambient) pressure but sealed and that the valve isclosed. Upon opening the valve, the condition established is

P1VCELL = P2(VCELL + VEXP) (1)

where P2 is the resulting intermediate pressure. The use of gauge pressures is per-missible because it is equivalent to having subtracted a constant from both sidesof the equation.

Placement of VCALIB into VCELL and repetition of the charging and expansionyields

P1*(VCELL - VCALIB) = P2*(VCELL - VCALIB + VEXP) (2)

where P1* and P2* are the before and after expansion pressures with VCALIB inplace.

VCALIB, P1, P2, P1*, and P2* are assumed to be known or measurable. VCELL andVEXP are to be found. Solving equation (1 for VEXP yields

VEXP = VCELL P1 − P2

P2(3)

Model 1305 MultiVolume Pycnometer Appendix D

Jun 99 D-1

Substitution of equation (3) into equation (2) yields

P1∗ (VCELL − VCALIB) = P2∗ (VCELL − VCALIB) + P2∗ VCELL

P1 − P2

P2

(4)

Gathering terms and solving for VCELL further yields

VCELL = VCALIB (P1∗ − P2∗)

(P1∗ − P2∗) −

P2∗P2

(P1 − P2)

(5)

Substitution of experimental and known values into equation (5) yields VCELL

which when used in equation (3) yields VEXP, the desired result.

Appendix D Model 1305 MultiVolume Pycnometer

D-2 Jun 99

INDEX

INDEX

!>35/<35 valve, 3-2>5/<5 valve, 3-2

AAccessories, ordering, 5-1Analysis

performing, 3-12theory, A-1

Analyzercalibrating, 3-16, 3-17, 3-18controls and components, 3-1description, 1-3environment, 1-7, 2-2Precautions and intended use, 1-5schematic, 1-4selecting voltage, 2-2specifications, 1-6startup procedure, 3-8turning off/shutting down, 3-19unpacking and inspecting, 2-1

CCalibration

See also Analyzercalculations, D-1verifying, 3-15volume, 3-5

Controls and components, 3-1Conventions, manual, 1-2

DDensity, calculating, 3-14

EEquipment

See Analyzer

FFILL RATe valve, 3-3FILL valve, 3-2Filter, 3-6Forms, A-3

GGas

regulator, 2-6regulator, attaching to analyzer, 2-6requirements, 1-7

Gas inlet pressure, 1-5Gas inlet/outlet, 3-6

IInsert

See Sample chamber

NNotes, 1-2

OOrdering information, 5-1Over-pressure relief valve, 3-6

PParts, ordering, 5-1Precautions, 1-5PREP/TEST valve, 3-3Pressure

display, 3-4transducer, 3-5unstable, 4-1

Pressure indicatorfails to illuminate, 4-4

Purge procedure, 3-12

Model 1305 MultiVolume Pycnometer Index

Jun 99 Index-1

RReproducibility, 4-2

SSample

cup, 3-4preparation, 3-11results computation, C-1volume, specifications, 1-6

Sample chamber, 1-3, 3-4cap, 3-5cleaning, 3-8insert, 1-6, 3-4insert, installing, 3-8insert, removing, 3-9o-ring, 3-5

Sample volumecalculating, 3-14specific, 3-15valve settings, 3-10

Scale factor, 3-15

TTheory, A-1Troubleshooting, 4-1

incorrect measured volume, 4-3reproducibility, 4-2

VVacuum, 1-7Valve

>35/<35, 3-2>5/<5, 3-2FILL, 3-2FILL RATE, 3-3overpressure relief, 3-6PREP/TEST, 3-3VENT, 3-2VENT RATE, 3-3

Vent Rate valve, 3-3Vent valve, 3-2Voltage, 1-7

selecting, 2-2Volume

ranges, 3-2See also Sample volume

WWarnings, 1-2

ZZero

adjustment, 3-2offset, 3-15pressure, 4-5

Index Model 1305 MultiVolume Pycnometer

Index-2 Jun 99

Documents

Model 1305 MultiVolume Pycnometer - Micromeritics