Parr Instrument 1108R User Manual

1108R

Oxygen Combustion Vessel

Operating Instruction Manual

662M

1108R Oxygen Combustion Vessel

Preface 3

Scope 3

Head Seal Modification 3

Related Instructions 3

Customer Service 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: [phone]

E-mail: [e-mail] • 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