Parr Instrument 1108 User Manual
1108
Oxygen Combustion Vessel
Operating Instruction Manual
205M
1108 Oxygen Combustion Vessel
Table of Contents
Preface
Scope — 3
Related Instructions — 3
Operating the 1108 Oxygen Combustion Vessel
Precautions — 4
Special Alloy Construction — 4
A Chlorine-Resistant Bomb — 4
1108B Oxygen Combustion Vessel — 4
Other Special Purpose Bombs — 4
Allowable Sample Size — 4
Attaching the Fuse — 5
Liquids in the Bomb — 5
Closing the Bomb — 5
Filling the Bomb — 6
Firing the Bomb — 6
Recovering the Combustion Products — 7
An Optional Recovery Procedure — 7
Samples and Sample Holders
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
Operating Suggestions
Poor Combustion — 11
Oxygen Charging Pressure — 11
Maintenance and Safety Instructions
Vessel Maintenance — 12
Vessel Repairs and Proof Tests — 13
1108 Maintenance Checklist — 14
Parts
1108 Parts Diagram Key — 16
Parts for the 1108 Oxygen Combustion Vessel — 17
Parts for the 2901 Ignition Unit — 18
Parts for the 1825 Oxygen Filling Connection — 19
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Parr Instrument Company
1108 Oxygen Combustion Vessel
Preface
Scope
These instructions cover the procedures to be followed when using a Parr 1108 Oxygen Combustion
Vessel to determine calorific values of solid or liquid
combustible material in a Parr calorimeter, or when
using an 1108 vessel 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 1108 Oxygen
Combustion Vessel, and to be well aware of the precautions to be observed in its operation. Calorimeter
operations and the operation of various oxygen combustion vessel accessories are described in separate
instruction manuals listed below, copies of which are
available upon request.
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
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.
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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1108 Oxygen Combustion Vessel
Operating the 1108 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
pages 8-9.
• 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 12 before starting to use the
bomb, and urge all operating personnel to reread these instructions often.
• 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.
Special Alloy Construction
The standard 1108 Oxygen Combustion Vessel is
made of a special columbium-stabilized stainless
steel selected for it’s excellent resistance to the
mixed nitric and sulfuric acids generated in a 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 1108CL Oxygen
Combustion Vessel described below. It should be
noted that all instructions for the 1108 apply equally
to the 1108CL as well.
A Chlorine-Resistant Bomb
The 1108CL Combustion Vessel is the same as the
standard 1108 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 1108CL Combustion Vessel instead of 1108 for its longer service life under
extreme corrosive conditions. Bomb maintenance
is also improved. In most cases, 1108CL returned
to the factory for scheduled maintenance can be
restored to optimum finish by repolishing instead of
having to rebore the cylinder to remove pits.
1108B Oxygen Combustion Vessel
The 1108B and 1108BCL Combustion Vessels are
identical to the 1108 and 1108CL models except for
the screw cap and cylinder. The 1108B and 1108BCL
have a heavy duty screw cap allowing for higher
energy release per sample. The cylinder has been
adapted to comply with Indian Standard IS 1350.
Other Special Purpose Bombs
Although the 1108 and 1108CL Combustion Vessels
will handle a broad range of test samples, Parr also
offers other special purpose combustion bombs,
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.
Allowable Sample Size
To stay within safe limits, the bomb should never be
charged with a sample which will release more than
8000 calories (1108) or 10,000 calories (1108B) when
burned in oxygen, and the initial oxygen pressure
should never exceed 40 atmospheres (590 psig).
This generally limits the mass of the combustible
charge (sample plus benzoic acid, gelatin, firing 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.
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A38A Head Support & Stand
45C10 Fuse Wire
Set the bomb head on the A38A
support stand when attaching the
fuse and arranging the sample.
To attach the fuse: raise the cap,
insert the wire through the eyelet, then pull the cap downward
to complete the assembly.
1108 Oxygen Combustion Vessel
Fuse Wire Fastened Between Two Electrodes
Attaching the Fuse
Set the bomb head on an A38A support stand and
fasten a 10 cm length of fuse wire between the two
electrodes. Parr 45C10 nickel alloy wire is used for
most tests, with platinum wire offered as an alternate for certain special procedures. The 45C10 wire
is furnished on cards from which uniform 10 cm
lengths can be cut without further measurement.
Quick-grip electrodes now installed in all new 1108
Oxygen Combustion Vessels eliminate most of the
threading and twisting formerly required when binding the wire to plain electrodes. To attach the fuse to
quick-grip electrodes, insert the ends of the wire into
the eyelet at the end of each stem and push the cap
downward to pinch the wire into place. No further
threading or twisting is required. The procedure for
binding the fuse to the 4A and 5A plain electrodes
in older Parr vessels is illustrated in the instruction manual furnished with the original equipment.
For convenience, it is recommended that the user
purchase and install new 4A10 and 5A10 quick-grip
electrodes as replacements for the 4A and 5A styles
in older equipment.
Place the fuel capsule with its weighed sample in
the electrode loop and bend the wire downward toward the surface of the charge as shown above. It is
not necessary to submerge the wire in a powdered
sample. In fact, better combustions will usually be
obtained if the loop of the fuse is set slightly above
the surface. When using pelleted samples, bend the
wire so that the loop bears against the top of the
pellet firmly enough to keep it from sliding against
the side of the capsule. It is also good practice to
tilt the capsule slightly to one side so that the flame
emerging from it will not impinge directly on the tip
of the straight electrode.
Liquids in the Bomb
Most 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. When
working with older bombs which have a removable
compression ring, be sure that the 104A2 ring is in
place above the gasket before attaching the screw
cap. Current model A416A3 Head Assemblies do not
require a separate compression 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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1108 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. Older bombs use a
threaded connector with a knurled coupling which
must be turned finger tight.
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. 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. The bomb inlet check valve will close
automatically when the oxygen supply is shut off,
leaving the bomb filled to the highest pressure indicated on the 0-55 atm. Gage. 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, adjust the water flow
rate so that the bomb will be covered by a continuous flow of cold water during the firing period, 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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