Parr Instrument 1108R User Manual

1108R
Oxygen Combustion Vessel
Operating Instruction Manual
662M
1108R Oxygen Combustion Vessel
Preface 3
Operating the 1108R Oxygen Combustion Vessel 4
Precautions 4
Special Alloy Construction 4
A Chlorine-Resistant Bomb 4
Other Special Purpose Bombs 4
Allowable Sample Size 5
Attaching the Cotton Thread 5
Liquids in the Bomb 5
Closing the Bomb 5
Filling the Bomb 6
Recovering the Combustion Products 7
An Optional Recovery Procedure 7
Operating Suggestions 11
Poor Combustion 11
Oxygen Charging Pressure 11
Maintenance and Safety Instructions 12
Bomb Maintenance 12
Bomb Repairs and Proof Tests 13
1108R Maintenance Checklist 14
Parts 16
1108R Parts Diagram Key 16
Parts for the 1108R Oxygen Combustion Vessel 17
Parts for the 2901 Ignition Unit 18
Parts for the 1825 Oxygen Filling Connection 19
Samples and Sample Holders 8
Particle Size and Moisture Content 8
Combustion Aids 8
Sample Pellets 8
Combustion Capsules 8
Foodstuffs and Cellulosic Materials 9
Coarse Samples 9
Corrosive Samples 9
Liquid Samples 9
Gelatin Capsules 9
Tape-Sealed Sample Holders 10
Heavy Oils 10
Explosives and High Energy Fuels 10
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Parr Instrument Company
1108R Oxygen Combustion Vessel
Preface

Scope

These instructions cover the procedures to be fol­lowed when using a Parr 1108R Oxygen Combustion Vessel to determine calorific values of solid or liquid combustible material in a Parr calorimeter, or when using an 1108R in a 1901 Oxygen Vessel Apparatus to prepare solid or liquid samples for chemical analysis. The user should study these instructions carefully in order to obtain a complete understand­ing of the capabilities and limitations of an 1108R, and to be well aware of the precautions to be ob­served in its operation. Calorimeter operations and the operation of various oxygen vessel accessories are described in separate instruction manuals listed below, copies of which are available upon request.
Note About Nomenclature:
Historically, burning a sample enclosed in a high pressure oxygen environment is known as Oxygen Bomb Calorimetry and the vessel containing the sample is known as an Oxygen Bomb. The terms bomb and vessel are used interchangeably.
Head Seal Modification
The 1108R differs from the standard 1108 series oxygen combustion vessel in that the head seals using a quad ring rather than an o-ring. To insure proper compression of the quad ring a separate con­tact ring is used in conjunction with the screw cap.
Otherwise the head is similar to the one used in the 1108P in that a wire is heated to ignite a cotton thread that in turn ignites the sample.
This model is offered to users that have older models incorporating this type of seal.

Related Instructions

No. Description
201M Limited Warranty 207M Analytical Methods for Oxygen Bombs 230M Safety in the Operation of Laboratory
and Pressure Vessels
483M Introduction to Bomb Calorimetry

Customer Service

Questions concerning the installation or operation of this instrument can be answered by the Parr Customer Service Department:
1-309-762-7716 • 1-800-872-7720 • Fax: 1-309-762-9453
E-mail: parr@parrinst.com • http://www.parrinst.com
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1108R Oxygen Combustion Vessel

Operating the 1108R Oxygen Combustion Vessel

Precautions

Combustion with oxygen in a sealed bomb is a very effective and reliable method for releasing all heat energy obtainable from a sample and for preparing hydrocarbon compounds and carbonaceous materi­als for analysis, but there are certain precautions which must always be observed when using this equipment. In particular:
Do not overcharge the bomb with too much sample or with a sample which might react with explosive violence.
Do not overcharge the bomb with too much oxygen. The initial charging pressure should not
exceed 40 atm (590 psig).
Do not fire the bomb alone on an open bench
without providing a protective cooling medium. The bomb should be completely submerged in water during firing.
Do not fire the bomb if gas bubbles are released from any point on the bomb when it is sub­merged in water.
Do not ignite a volatile sample without using one of the sealed sample holders described on page 9 or the tape technique.
Stand away from the bomb during and do not handle the bomb for at least 6 minutes after fir­ing.
Keep the bomb in good condition at all times. Any parts that show signs of weakness or dete­rioration must be replaced promptly.
Read the maintenance and safety instructions beginning on page 10 before starting to use the bomb, and urge all operating personnel to re­read these instructions often.

Special Alloy Construction

The standard 1108R Oxygen Combustion Vessel is made of a special niobium-stabilized stainless steel selected for it’s excellent resistance to the mixed nitric and sulfuric acids generated in a bomb com­bustion. It is a superior alloy which will withstand the conditions generated in almost all fuel testing applications, yet neither it nor any other stainless steel will resist the corrosive atmospheres pro­duced when burning samples containing halogen
compounds. For these applications, Parr offers the
1108RCL Combustion Vessel described below. It should be noted that all instructions for the 1108R apply equally to the 1108RCL as well.

A Chlorine-Resistant Bomb

The 1108RCL Combustion Vessel is the same as the standard 1108R model, but with a head and cylinder made of an alloy with superior corrosion resistance to the free chlorine and halogen acids released when burning chlorinated samples. Users who analyze waste materials and combustible solvents are urged to select the 1108RCL Combustion Vessel instead of 1108R for its longer service life under extreme corrosive conditions. Bomb maintenance is also improved. In most cases, 1108RCL vessels returned to the factory for scheduled maintenance can be restored to optimum finish by polishing instead of having to rebore the cylinder to remove pits.

Other Special Purpose Bombs

Although the 1108R and 1108RCL Combustion Vessels will handle a broad range of test samples, Parr also offers other special purpose combustion vessels, including: a high pressure bomb for ex­plosives, an oversize bomb for large samples and a semi-micro bomb for small samples. Separate operating instructions are issued for these special bombs.
Screw caps and cylinders are stamped so that each cylinder and screw cap can be identified as a matched set. We recommend that you maintain the match of cylinders and screw caps for your safety and ease of use.
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Parr Instrument Company
1108R Oxygen Combustion Vessel
845DD2 Cotton Ignition Thread
To attach the fuse either twist or tie the cotton thread to the A40DD2 semi-permanent fuse wire.

Allowable Sample Size

To stay within safe limits, the bomb should never be charged with a sample which will release more than 8000 calories when burned in oxygen, and the initial oxygen pressure should never exceed 40 atmo-
spheres (590 psig). This generally limits the mass of
the combustible charge (sample plus benzoic acid,
gelatin, ring oil or any combustion aid) to not more
than 1.1 grams. When starting tests with new or unfamiliar materials it is always best to use samples of less than 0.7 of a gram, with the possibility of increasing the amount if preliminary tests indicate no abnormal behavior. To avoid damage to the bomb and possible injury to the operator, it should be a standing rule in each laboratory that the bomb
must never be charged with more than 1.5 grams of
combustible material.

Attaching the Cotton Thread

A cotton thread (845DD2) is used as an auxiliary
fuse to ignite the sample. Ten centimeters of thread is recommended for this auxiliary thread which is looped over the heating wire, doubled on itself, twisted to form a single strand and fed into the sample cup to lay on the sample.
When contact is made through the heating wire, the thread will ignite, drop into the sample cup and ignite the sample.
A38A Head Support Stand
Set the bomb head on the A38A support stand when
attaching the fuse and arranging the sample.

Liquids in the Bomb

Most bomb combustion procedures call for a small amount of liquid to be placed in the bottom of the bomb as a sequestering agent and absorbent. If the amount and type of liquid are not otherwise speci­fied, add 1.0 mL of distilled or deionized water from a pipet.

Closing the Bomb

Care must be taken not to disturb the sample when moving the bomb head from the support stand to the bomb cylinder. Check the sealing ring to be sure that it is in good condition and moisten it with a bit of water so that it will slide freely into the cylinder; then slide the head into the cylinder and push it
down as far as it will go. For easy insertion, push
the head straight down without twisting and leave the gas release valve open during this operation. Make sure that the contact ring is positioned flat on top of the sealing ring. Set the screw cap on the cylinder and turn it down firmly by hand to a solid stop. When properly closed, no threads on the cylinder should be exposed. If the screw cap tends to bind to the cylinder at this point, indicating that it might be difficult to open the bomb after it has been fired, turn the screw cap back slightly – but only a few degrees – enough to release the binding, since the bottom thread must remain fully engaged. It is not necessary to use a wrench or spanner on the screw cap. Hand tightening should be sufficient to secure a tight seal.
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1108R Oxygen Combustion Vessel

Filling the Bomb

The instructions below describe a manual system
using the 1825 Oxygen Filling Connection furnished
with other Parr apparatus.
Oxygen for the bomb can be drawn from a standard commercial oxygen tank. Unscrew the protective cap from the tank and inspect the threads on the valve outlet to be sure they are clean and in good condi­tion. Place the ball end of the connection into the outlet socket and draw up the union nut tightly with
a wrench, keeping the 0-55
atm gage in an upright position.
The pressure connection to the bomb is made with a slip connector on the oxygen hose which slides over the gas inlet fitting on the bomb head. Slide the connector onto the inlet valve body and push it down as far as it will go. If it does not slide easily, a drop of water spread around the inlet valve will lubricate the sealing rings.
Close the outlet valve on the bomb head; then open or “crack” the oxygen tank valve not more than one-quarter turn. Open the filling connection control valve slowly and watch the gage as the bomb pres­sure rises to the desired filling pressure (usually 30
atm., but never more than 40 atm.); then close the
control valve. The bomb inlet check valve will close automatically when the residual pressure in the fill­ing hose is released, leaving the bomb filled to the
highest pressure indicated on the 0-55 atm. Gage.
Release the residual pressure in the filling hose by pushing downward on the lever attached to the relief valve. The gage should now return to zero. If the pressure drops slowly and a large amount of gas escapes when the pressure relief valve is opened, the check valve in the bomb head is not operating properly. This trouble will have to be corrected before the bomb can be used. If too much oxygen should accidentally be introduced into the bomb, DO NOT proceed with the combustion. Detach the filling connection; exhaust the bomb; remove the head and reweigh the sample before repeating the filling operation.
1825 Oxygen Filling
Connection
Firing the Bomb
The electric current for firing the bomb should be drawn from a Parr 2901EB Ignition Unit
connected to an 115V 50/60Hz grounded elec­trical outlet. (For 230V 50/60Hz use a 2901EE Ignition Unit). Connect
one of the lead wires from the calorimeter to the 10 cm binding post on the ignition unit and the 2nd wire to the middle or “common” terminal.
When using the bomb in a calorimeter, insert the 421A lifting handle into the two holes in the side of the screw cap and lower the bomb partially into the calorimeter water bucket. Press the banana plugs on the two ignition wires firmly into the terminal sockets on the bomb head before the head is com­pletely immersed in the water. After connecting the wires, lower the bomb into the bucket with its feet spanning the circular boss in the bottom of the bucket. Remove the lifting handle and shake off any drops of water back into the bucket. Be careful not to remove any water from the bucket with the fingers. When using the bomb alone for analytical purposes it should be connected to the ignition unit as de­scribed above and held submerged in an A387A or similar water bath during firing.
In all operations, check the bomb for leaks before firing. If any gas leakage is indicated, no matter how slight, DO NOT FIRE THE BOMB. Instead remove it from the water bath; release the pressure and eliminate the leak before proceeding with combus­tion test. If no leakage is indicated, then stand back and press the firing button on the ignition unit to fire the charge.
Caution! Do not have the head, hands or any parts of the body directly over the bomb during the firing period and do not go near the bomb for at least 20 seconds after the firing.
2901 Ignition Unit
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Parr Instrument Company
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