Page 1
1108P
Oxygen Combustion Vessel
Operating Instruction Manual
418M
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1108P Oxygen Combustion Vessels
Preface 3
Scope 3
Related Instructions 3
Customer Service 3
Operating the 1108P Oxygen Combustion Vessel 4
Precautions 4
Special Alloy Construction 4
A Chlorine-Resistant Bomb 4
1108BP Oxygen Combustion Vessel 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
Firing 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
1108P Maintenance Checklist 14
Parts 16
1108P Parts Diagram Key 16
Complete Assemblies 16
Parts for the 1108P 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
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1108P Oxygen Combustion Vessels
Preface
Scope
These instructions cover the procedures to be followed when using a Parr 1108P Oxygen Combustion
Vessel to determine calorific values of solid or liquid
combustible material in a Parr calorimeter, or when
using an 1108P Vessel in a 1901 Oxygen Bomb 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 1108P,
and to be well aware of the precautions to be observed in its operation. Calorimeter operations and
the operation of various oxygen bomb 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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1108P Oxygen Combustion Vessels
Operating the 1108P 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 8-10.
Special Alloy Construction
The standard 1108P 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
1108PCL described below. It should be noted that
all instructions for the 1108P apply equally to the
1108PCL as well.
A Chlorine-Resistant Bomb
The 1108PCL is the same as the standard 1108P
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 1108PCL instead of 1108P for its longer
service life under extreme corrosive conditions.
Bomb maintenance is also improved. In most cases,
1108PCL Oxygen Combustion 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.
• 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.
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Parr Instrument Company
1108BP Oxygen Combustion Vessel
The 1108BP and 1108BPCL Combustion Vessels are
identical to the 1108P and 1108PCL models except
for the screw cap and cylinder. The 1108BP and
1108BPCL 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 1108P and 1108PCL 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.
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1108P Oxygen Combustion Vessels
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. 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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1108P Oxygen Combustion Vessels
Filling the Bomb
The instructions below describe a manual system us-
ing 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, keep-
ing 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 oxygen supply is shut off,
leaving the bomb filled to the highest pressure in-
dicated 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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1108P Oxygen Combustion Vessels
Fire the charge by pressing the ring button on the
ignition unit, keeping the circuit closed for about 2
seconds. The indicator light will come on when the
button is depressed and will remain on while the
button is depressed.
If the indicator light does not come on when the
firing button is pressed there is either a fault in the
2901 or an open circuit in the system. Check for
voltage between the 10 cm and common terminals of the 2901. Approximately 23 VAC should be
measured. If there is no voltage present, check the
fuse inside the 2901. An open circuit can usually be
located with an ohmmeter. Flex the lead wires during any continuity check as the wires may be broken
and making only intermittent contact. If the red indicator light glows during ignition but the bomb fuse
does not burn, check the system for a voltage leak
to ground, most likely in the insulated electrode on
the bomb head. Check the electrode using the high
impedance scale on an ohmmeter and replace the
electrode insulator and seal if leakage is indicated.
Recovering the Combustion Products
Let the bomb stand in the calorimeter or water bath
for at least 3 minutes, then lift it out of the water
and wipe with a clean towel. Open the valve knob
slightly to release all residual gas pressure before
attempting to remove the screw cap.
Caution!
Do NOT have any part of the body in the
exhaust path of the bomb.
Gas release should proceed slowly over a period
of not less than one minute to avoid entrainment
losses. After all pressure has been released, unscrew the cap; lift the head out of the cylinder and
place it on the support stand. Do not twist the head
during removal. Pull it straight out to avoid sticking.
Examine the interior of the bomb for soot or other
evidence of incomplete combustion. If such is found
the test will have to be discarded. Wash all interior
surfaces of the bomb and the combustion capsule
with a jet of distilled water and collect the washings.
If any precipitate or residue is present, remove it
with a rubber policeman. Do not filter the washings
as this might remove valuable constituents. Titrate
the washings and measure the unburned fuse wire
as required for calorific tests, then analyze the washings for sulfur and other elements, if required.
An Optional Recovery Procedure
If desired, a luer tting, 518A, can be attached to the
bomb to provide a means for washing the bomb
and recovering the combustion products with a
syringe without opening the bomb and removing
the bomb head. To use this procedure, remove the
standard A420A valve needle and replace it with an
A420A2 needle to which a syringe, 244C, can be attached.
To recover the combustion products via a luer fitting, let the bomb stand in a cooling bath for at
least 3 minutes after firing to allow for complete
condensation of all residual vapor. Then remove the
bomb from the water and attach only the barrel of a
244C syringe to the luer fitting. Open the valve and
release the pressure at a slow rate, using at least
a full minute to bring the bomb pressure back to
atmospheric. The attached syringe barrel will help to
retain any condensate spray that might be carried
out of the valve during the exhaust period.
Add 30 mL of distilled water to the attached syringe
barrel and use the syringe plunge to force the water
into the bomb, then close the valve while holding
the plunger down. This will develop sufficient pressure within the bomb to seat the inlet check valve
and provide enough positive pressure to help remove the washings. Agitate and rotate the bomb in
a horizontal position to wet all inner surfaces, then
turn the bomb upside down over a 600 mL beaker
and open the valve to discharge the washings into
the beaker. Tilt the bomb slightly toward the valve
to get as much of the water out as possible. Repeat
this back-flushing procedure two times, collecting
a total of 90 to 100 mL of washings, then open the
bomb and recover any liquid that may remain in the
cylinder. The three complete back flush and rinse
cycles should recover better than 99 percent of the
combustion products.
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1108P Oxygen Combustion Vessels
Samples and Sample Holders
Particle Size and Moisture Content
Solid samples burn best in an oxygen bomb when
reduced to 60-mesh, or smaller, and compressed
into a pellet with a Parr Pellet Press. Particle size is
important because it influences the reaction rate.
Large particles may not burn completely and small
particles are easily swept out of the capsule by
turbulent gases during the rapid combustion. Compression into a pellet is recommended since a pellet
burns less vigorously than a loose sample, resulting
in fewer incomplete combustions.
Materials such as coal burn well in the as-received
or air-dry condition, but DO NOT BURN BONE-DRY
SAMPLES. A certain amount of moisture is desirable in order to control the burning rate. Very dry
samples may burn so rapidly that a flame might
reach the seals or the soft valve seat in the bomb
head, igniting these parts and possibly causing a
serious burn-out through the head. Moisture contents up to 20% can be tolerated in many cases, but
the optimum moisture is best determined by trial
combustions. If moisture is to be added, drop water
directly into a loose sample or onto a pellet after the
sample has been weighed; then let the sample stand
for awhile to obtain uniform distribution.
2811 Pellet Press
offers a convenient means for preparing samples
in this manner. Pellets produced in this press are
ejected into a stainless steel receiver from which
they can be lifted and handled easily with a pair of
forceps. Most pellets for use in the 1108P Oxygen
Combustion Vessel are made in a one-half inch diameter size, but smaller diameters can be produced
in the same press using interchangeable punch and
die sets. Complete pellet making instructions are
furnished with each press.
Combustion Aids
Some samples may be difficult to ignite, or they
may burn so slowly that the particles become chilled
below the ignition point before complete combustion is obtained. In such cases benzoic acid, white oil
or any other combustible material of known purity
can be mixed with the sample. Ethylene glycol,
butyl alcohol or decalin may also be used for this
purpose. It must be remembered, however, that a
combustion aid adds to the total energy released in
the bomb and the amount of sample may have to be
reduced to compensate for the added charge. If benzoic acid is added as a combustion aid, it must be
added in a pellet form, .2 gm pellets. Never combust
benzoic acid in powder form.
Sample Pellets
One of the most useful techniques for handling
powdered samples is to compress the material into
a tablet or pellet before it is weighed. Pellets are
easier to handle than loose samples and they burn
slower in the bomb, thereby reducing the chances
for incomplete combustion. The Parr pellet press
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Parr Instrument Company
Combustion Capsules
Non-volatile samples to be tested in Parr oxygen
vessels are weighed and burned in shallow capsules
measuring approximately 1” diameter and 7/16”
deep. These are available in stainless steel, fused
silica and platinum alloyed with a 3-1/2% rhodium.
Stainless steel capsules are suitable for all tests
except those in which a non-metallic (fused silica)
holder is desired or where the superior corrosion
resistance of a Pt-Rh cup is required. Fused silica
capsules should be used for samples containing
dissolved metals which can ignite a stainless steel
capsule and cause serious bomb damage.
Stainless steel capsules will soon acquire a dull grey
finish after repeated use in an oxygen bomb due to
the formation of a hard, protective oxide film. This
dull finish not only protects the capsule but it also
promotes combustion and makes it easier to burn
the last traces of the sample. It is recommended,
therefore, that capsules be heated in a muffle fur-
nace at 500°C for 24 hours to develop this protective
coating uniformly on all surfaces. This treatment
should be performed after a capsule has been pol-
Page 9
3601 Gelatin Capsules
43A6 Combustion Capsule with
Adhesive Tape Seal
1108P Oxygen Combustion Vessels
43AS Combustion Capsules
ished with an abrasive to remove any ash or other
surface deposits. Heating in a muffle is also a good
way to destroy any trace of carbon or combustible
matter which might remain in the capsule from a
previous test. After heating, place the capsules in a
clean container and handle them only with forceps
when they are removed to be weighed on an analytical balance.
Capsules should be monitored for wear. Do not use
the capsule if the wall or base thickness is less than
0.025”.
Foodstuffs and Cellulosic Materials
Fibrous and uffy materials such as vegetable bers
may have to be packed into the combustion capsule
and moistened to slow the burning rate, but foodstuffs and cellulosic samples generally burn with
little difficulty. Partial drying may be necessary if the
moisture content is too high to obtain ignition. But
if the sample is heat sensitive and cannot be dried,
a water soluble combustion aid such as ethylene
glycol can be added to promote ignition.
Coarse Samples
Corrosive Samples
Although the Parr bomb is made of corrosion resistant alloys, repeated use with high sulfur samples or
with samples containing over 20 mg of chlorine may
corrode the metal surfaces and produce a dull film
on the inner walls of the bomb. Materials containing appreciable amounts of caustic; such as dried
black liquor from a pulp mill, may also damage the
bomb, with the caustic attacking the alloy capsule
and causing the metal capsule and the bomb electrodes to ignite and burn. These corrosive attacks on
the bomb can be reduced by using smaller samples
and by increasing the amount of liquid placed in the
bottom of the bomb. If a corrosive film develops on
the bomb surfaces it should be removed by proper
polishing before it grows to a point where deep pitting occurs.
Liquid Samples
Non-volatile samples are treated in the same manner as solid materials. Oils and other liquids which
are not volatile at room temperature can be weighed
directly into open combustion capsules. The cotton
thread should be positioned just slightly above the
surface of the sample or just touching the surface.
In most cases it may be necessary to burn coarse
samples without size reduction since grinding or
drying may introduce unwanted changes. There is
no objection to this if the coarse sample will ignite and burn completely. Whole wheat grains and
coarse charcoal chunks are typical of materials
which will burn satisfactorily without grinding and
with no additives or special procedure.
Gelatin Capsules
Volatile liquid samples to be burned in an oxygen
bomb can be handled conveniently in Parr 3601
Gelatin Capsules. These 0.9 mL capsules consist of
two cups which telescope together with a friction fit
adequate to retain most liquids. Corrections must
be made for the heat of combustion of gelatin (ap-
proximately. 4600 cal/g) if the capsules are used for
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1108P Oxygen Combustion Vessels
calorimetry, and for the sulfur content of the gelatin
(approximately. 0.35%) if used for sulfur determinations. Blank tests must be run to determine the exact
amounts. Gelatin capsules should always be stored
in sealed bottles and handled with due regard for
their hygroscopic nature.
The blank tests should be repeated at frequent intervals since values determined on a weight basis will
change if there are variations in the moisture content of the gelatin.
Tape-Sealed Sample Holders
Volatile samples can be handled in a standard 43AS
combustion capsule with a flat top rim, or in a 43A6
platinum capsule with a spun rim by covering the
top of the capsule with a disc of adhesive plastic
tape. To seal a capsule; stretch a piece of tape across
the top and press it firmly against the rim with a flat
blade, then trim the excess with a sharp knife. The
seal obtained in this manner will be adequate to
retain most volatile samples. The tape used for this
purpose should be free of chlorine and as low in sulfur as possible. Borden “Mystic Tape” No. M-169-C,
or 3M Transparent Tape No. 610 are recommended
for this purpose. Equivalent tape can be obtained
from Parr under Part No. 517A. The weight of the
tape disc must be determined separately and a correction applied for any elements in the tape which
might interfere with the determination. This can be
done by running a blank test with the tape alone using a sample weighing about 1.0 gram. Tape should
always be stored in a sealed container to minimize
changes in its moisture content.
Use the following procedure when filling and handling any of these tape-sealed sample holders;
Weigh the empty cup or capsule; then cover the top
with tape, trim with a knife and press the trimmed
edge firmly against the metal rim. Also cut and attach a small flag to the disc; as illustrated at the top
of page 9. Puncture the tape at a point below the
flag, then reweigh the empty cup with its tape cover.
Add the sample with a hypodermic syringe; close
the opening with the flag and reweigh the filled
cup. Set the cup in the loop electrode and arrange
the cotton thread so that it touches the center of the
tape disc.
Just before closing the bomb, prick the disc with
a sharp needle to make a small opening which is
needed to prevent collapse of the disc when pres-
sure is applied. Fill the bomb with oxygen to the
usual charging pressure, but add oxygen slowly so
that the tape will not collapse into the cup. Fire the
bomb and complete the test in the usual manner.
Low volatile samples with a high water content,
such as urine or blood, can be burned in an open
capsule by absorbing the liquid on filter paper pulp
or by adding a combustion aid, such as ethylene
glycol or by freeze drying the sample.
Heavy Oils
Oils and other liquids which are not volatile at room
temperature can be weighed directly into open combustion capsules. The cotton thread should be positioned just slightly above the surface of the sample
or just touching the surface.
Several precautions must be observed when testing
heavy oils because of the intense heat which they
develop. If the wall of the metal combustion capsule
is thin, or if some of the sample happens to have
been spread on the thin rim of the capsule, it is possible that the metal may become heated to the point
where it will ignite. This condition is serious because
of the excessive heat liberated when metal burns in
oxygen. Also, the molten metal oxides may damage
the interior of the bomb. In extreme cases the bomb
electrodes may also ignite and burn with similar
results. For these reasons, be sure that any capsule
holding a heavy oil is in good condition and not
worn thin from prior usage. Also, bend the straight
electrode so that it does not project over the cup
where it will receive the full flame from the sample.
It is always desirable to tilt the capsule slightly in the
loop holder so as to direct the flame away from both
electrodes. Some operators prefer to use a 10 to 13
mL platinum crucible for holding heavy oil samples
because the added depth in a crucible promotes
slower combustion and a milder flame.
Explosives and High Energy Fuels
Special precautions must be observed when testing
materials which release large volumes of gas upon
ignition, or which detonate with explosive force. Although most slow-burning gun powders and rocket
propellants can be tested in the conventional 1108
Oxygen Combustion Vessel, the user must understand that this bomb is not designed to withstand
the shock pressures produced by primers and high
explosives. It is much safer to test these materials in
a Parr 1104 High Pressure Oxygen Vessel.
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1108P Oxygen Combustion Vessels
Operating Suggestions
Poor Combustion
The difference in combustion characteristics of the
wide variety of materials which may be burned in an
oxygen bomb make it difficult to give specific directions which will assure complete combustions for all
samples. However, two fundamental conditions may
be stated. First, some part of the sample must be
heated to its ignition temperature to start the combustion and, in burning, it must liberate sufficient
heat to support its own combustion regardless of
the chilling effect of the adjacent metal parts. Second, the combustion must produce sufficient turbulence within the bomb to bring oxygen into the fuel
cup for burning the last traces of the sample.
An incomplete combustion in an oxygen bomb is
nearly always due to one or more of the following
causes:
1. Excessively rapid admission of gas to the bomb
during charging, causing part of the sample to
be blown out of the cup.
8. Insufficient space between the combustion
cup and the bottom of the bomb. The bottom
of the cup should always be at least one-half
inch above the bottom of the bomb, or above
the liquid level in the bomb, to prevent thermal
quenching.
9. Excessive moisture or non-combustible material
in the sample amounts to approximately 20
percent or more of the charge it may be difficult
to obtain complete combustion. This condition
can be remedied by adding a small amount of
benzoic acid or other combustion aid.
Oxygen Charging Pressure
Operators sometimes disagree as to the most desirable oxygen charging pressure. As a rule, it is best
to use the lowest gas pressure that will give complete combustion. Lower pressures permit higher
gas temperatures and greater turbulence, both of
which help to secure better combustion. The range
of charging pressures for Parr oxygen bombs usu-
ally falls between 25 and 35 atmospheres, and it
should never exceed 40 atmospheres.
2. Loose or powdery condition of the sample which
will permit unburned particles to be ejected
during a violent combustion.
3. The use of a sample containing coarse particles
which will not burn readily. Coal particles which
are too large to pass a 60-mesh screen may not
burn completely.
4. The use of a sample pellet which has been made
too hard or too soft. Either condition sometimes
causes spalling and the ejection of unburned
fragments.
5. The use of an ignition current too low to ignite
the charge.
6. Insertion of the cotton thread below the surface
of a loose sample. Best results are obtained by
barely touching the surface or by having the
cotton thread slightly above the sample.
7. The use of insufficient oxygen to burn the
charge, or conversely, the use of a very high
initial gas pressure which may retard the
development of sufficient gas turbulence within
the bomb.
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Page 12
1108P Oxygen Combustion Vessels
Maintenance and Safety Instructions
Bomb Maintenance
Under normal usage Parr oxygen bombs will give
long service if handled with reasonable care. However, the user must remember that these bombs
are continually subjected to high temperatures and
pressures which apply heavy stresses to the sealing
mechanism. The mechanical condition of the bomb
must therefore be watched carefully and any parts
that show signs of weakness or deterioration should
be replaced before they fail. Otherwise, a serious
accident may occur.
DO NOT FIRE THE BOMB if gas bubbles are observed anywhere indicating a possible gas leak.
Disassemble the parts and install new seals immediately. The bomb head parts which require closest
attention and most frequent replacement are: the
230A O-ring head gasket, all the 238A sealing rings,
the 415A O-ring and the 20VB PCTFE valve seat in
the needle valve.
When replacing the 230A head gasket, stretch the
new O-ring and let it snap into place to be sure that
it moves freely in its groove and is not twisted.
The 20VB valve seat in the needle valve deteriorates
with use, not only in the needle area but on the underside of the seat as well. Leakage and a possible
serious burn-out can result from a worn or damaged
seat if it is not replaced promptly. As a basic rule,
the 20VB valve seat and the two 238A O-rings on
the valve needle should be replaced after every 500
firings or every six months, whichever occurs first.
If the bomb is used for samples containing chlorine,
these parts should be replaced after every 250 rings.
To replace the valve seat, unscrew the 397A compression nut; remove the valve stem and the old
seat, and disassemble all of the parts. Drop a new
20VB valve seat into the body and push it down
into place. Slide a 7VBCM Monel washer, two 238A
O-rings and the 378A packing cup onto the A420A
valve needle assembly with the needle pointed upward; then adjust the parts on the needle so that the
tip of the needle is flush with-or slightly recessed
into-the bottom of the packing cup. Insert this assembly into the 396A outlet valve body and press it
firmly against the valve seat by tightening the 397A
compression nut to 100 inch-pounds of torque.
A Parr 475A Service Clamp offers a convenient
means for clamping the bomb head firmly in a vise
without damaging the head when replacing any of
the bomb head parts.
Keep the 397A compression nut on the valve needle
tightened rmly at all times. Frequent tightening
is important. This nut, if slightly loose, may allow a
leak to develop during the rapid pressure rise upon
ignition. This type of leak may not be detectable before firing; but if it develops, the hot gases can ignite
the 20VB valve seat and burn through the head.
Do not use extreme force when closing the needle
valve. A moderate but firm turn on the valve knob
should be sufficient to stop all gas flow. Excessive
needle pressure will deform and possibly close the
gas passage. If this happens, unscrew the valve
body and replace the 20VB valve seat. Accumulated
salt deposits may also clog the gas passage, making it difficult to release pressure at the end of a run.
To avoid this, clean the passage through the valve
needle and deflector nut with a small drill.
The 238A sealing ring in the insulated electrode
should be replaced with the same frequency as the
20VB valve seat. Also, keep the 411A terminal nut
tight at all times. As the 238A sealing ring ages and
hardens it becomes a partial electrical conductor,
permitting misfires and producing unwanted heating effects. Periodic replacement will eliminate this
potential problem.
The threads on the screw cap should be checked
routinely for any burns or other deformity. After
long use, the threads on the screw cap may become
worn to the point where they will no longer provide
a safe closure for the bomb, and the screw cap will
have to be replaced. The following procedure can be
used to check the extent to which the threads have
become worn:
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Parr Instrument Company
Page 13
1108P Oxygen Combustion Vessels
1. Assemble the bomb with the head in the cylinder and count the number of turns required
to bring the screw cap down firmly against the
head.
2. Then open the bomb; remove the head and
replace the screw cap, but turn it down to only
one-half of the turns previously counted. This
will usually be about four turns.
3. With the screw cap in this position, use a dial
gage to measure the vertical deflection when
lifting the screw cap upward. If this measure-
ment exceeds 1/32 inch (0.030”), the screw cap is
unsafe and should be discarded.
4. The cylinder can then be returned to the factory for inspection. If the threads on the cylinder
are in good condition, a new screw cap can be
custom-fitted to the cylinder.
Never under any circumstances use oil on the Orings which seals the bomb head or on any of the
valves or fittings which handle compressed oxygen.
This precaution applies to all of the oxygen bombs
parts to the oxygen filling connection as well.
Although Parr oxygen bombs are made from alloys
which will withstand most corrosive gases, these
bombs will not resist chlorine, fluorine or bromine
in the presence of moisture. If samples yielding
appreciable amounts of these elements are burned
in a Parr bomb, the interior surfaces may become
etched or corroded. In such cases the bomb should
be emptied and washed as quickly as possible after
each combustion.
Bomb Repairs and Proof Tests
The 20VB valve seat, 230A, 415A, and the four 238A
O-rings should be replaced after every 500 rings,
or every six months, whichever occurs first. If the
bomb is used for samples containing chlorine, these
repairs should be made after every 250 rings.
Parr oxygen bombs can be returned at any time for
repair and testing. A factory test is recommended
after every 5000 rings, or after any of the following
conditions; (a) red with an excessive charge, (b)
ignition of any internal components, (c) machined
by any source other than the factory, (d) damaged
by corrosive vapors that might have exceeded 80%
of the corrosion allowance, or (e) any changes in the
threads on the bomb cylinder and/or screw cap.
When returning a vessel to the factory, ship it to:
Parr Instrument Company
Attn: Repair Department
211- 53rd Street
Moline, Illinois 61265
A purchase order covering the repair work should be
included with the shipment or mailed to the same
address as no repairs will be started without specific
instructions. Be sure to include a return shipping
address and the name and telephone number of the
individual to be contacted if questions arise concerning excessive repair costs or other problems.
Individual repair parts can be ordered from any Parr
dealer or direct from the factory.
If the interior of the bomb should become etched
as mentioned above, the resistance of the metal
to further attack can be improved by restoring the
surface to its original highly polished condition.
Bombs needing repolishing or other repair work can
be returned to the factory. A periodic overhaul and
test at the factory will help to keep any Parr oxygen
bomb in first-class condition.
See page 14 for a Maintenance Checklist.
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Page 14
1108P Oxygen Combustion Vessels
1108P Maintenance Checklist
Refer to page 12-13 & 16-17 of the 1108P Operating Instruction Manual for assembly instructions and parts
diagram.
50 to 100 Test Maintenance
Date Date Date Date
Replace 840DD2
Heating Wire
Clean electrodes
500 Test Maintenance
Replace the following:
Date Date Date Date
230A
415A
238A (4)
143AC
20VB
Examine and replace if worn or cracked.
143AC
401A
96AC
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Parr Instrument Company
Page 15
Notes
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Page 16
1108P Oxygen Combustion Vessels
Parts
1108P Parts Diagram Key
KEY ITEM DESCRIPTION
103A
SCREW CAP
(1108P/1108PCL)
1
103A6
230A O-RING 2-3/8 ID BUNA-N
2
394A18 OXYGEN VESSEL HEAD, BARE
3
394A18CL
101A
101ACL
HEAVY DUTY SCREW CAP
(1108BP/1108BPCL)
OXYGEN VESSEL HEAD, BARE
FOR CHLORINE SERVICE
OXYGEN VESSEL CYLINDER
(1108P)
OXYGEN VESSEL CYLINDER
FOR CHLORINE SERVICE
(1108PCL)
4*
101A4
101A4CL
395A2 INLET VALVE BODY
5
415A O-RING 7/16 ID BUNA-N
6
238A O-RING 3/16 ID BUNA-N
7
403A CHECK VALVE
8
411A TERMINAL NUT
9
143AC INSULATOR, DELRIN
10
388A SPACER
12
SC1932SC10 SOCKET HEAD SET SCREW
13
655DD ELECTRODE SPACER
14
404A2
OXYGEN VESSEL CYLINDER
(1108BP)
OXYGEN VESSEL CYLINDER
FOR CHLORINE SERVICE
(1108BPCL)
DEFLECTOR NUT
(1108P/1108BP)
15
404A2CH
1095DD
DEFLECTOR NUT
(1108PCL/1108BPCL)
ELECTRODE
(1108P/1108BP)
16
1095DDCH
1095DD2
ELECTRODE
(1108PCL/1108BPCL)
ELECTRODE, INSULATED
(1108P/1108BP)
17
1095DD2CH
401A SLEEVE INSULATOR
19
96AC ELECTRODE INSULATOR
20
ELECTRODE, INSULATED
(1108PCL/1108BPCL)
KEY ITEM DESCRIPTION
A420A
407A VALVE KNOB
23
398A LOCK NUT
24
400A VALVE NEEDLE
25
397A COMPRESSION NUT
26
396A OUTLET VALVE BODY
27
7VBCM WASHER MONEL
28
378A PACKING CUP
29
20VB VALVE SEAT PCTFE
30
PA1332RD04 6-32 X 1/4 RHMS
31
840DD2
32
1095DD3
VALVE NEEDLE WITH KNOB
(NOS. 23, 24, 25)
60" IGNITION WIRE
(2.0" PER USE)
ELECTRODE W/ SETSCREW
(1108P/1108BP)
33
1095DD3CH
PC1332SC02 6-32 SHSS (ELECTRODE)
34
906DD2 CAPSULE HOLDER
35
43A_SERIES CAPSULE
36
ELECTRODE W/ SETSCREW
(1108PCL/1108BPCL)
Complete Assemblies
ITEM DESCRIPTION
AA101A
AA101A4
OXYGEN VESSEL CYLINDER WITH
103A SCREW CAP FOR (1108P)
OXYGEN VESSEL CYLINDER WITH
103A6 SCREW CAP (1108BP)
OXYGEN VESSEL CYLINDER
AA101ACL
OR CHLORINE SERVICE WITH
103A SCREW CAP (1108PCL)
OXYGEN VESSEL CYLINDER
AA101A4CL
FOR CHLORINE SERVICE WITH
103A6 SCREW CAP (1108BPCL)
A416A5
OXYGEN VESSEL HEAD ASSEMBLY
(1108P/1108BP)
OXYGEN VESSEL HEAD ASSEM-
A416A5CL
BLY FOR CHLORINE SERVICE
(1108PCL/1108BPCL)
* Sold as complete assembly, see Complete Assemblies table
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Parr Instrument Company
Page 17
1108P Oxygen Combustion Vessels
Parts for the 1108P Oxygen Combustion Vessel
23
24
25
1
26
27
5
10
19
9
7
7
8
6
9
2
28
7
29
12
7
13
30
3
15
14
20
4
16
31
17
32
31
15
14
33
34
35
36
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Page 18
1108P Oxygen Combustion Vessels
Parts for the 2901 Ignition Unit
ISO WARNING SYMBOL
34E2
174F
REF
2005E
11
10
12
TN1632HL
200F11
1157E
139E21
W/ SA1332RP04
711
(LOAD)
6
6
8
115V
9
5
8
2
115V
9
1
10
12
MOUNT TRANSFORMER
W/(4) UP18DM04
190F
GROUND SYMBOL
REF
2000E
12V
12V
3
7
8
5
11
4
12
(3) TN1332HL
7
6
A1580E
1
4
3
2014E
95F
(3) A59A2
(10 cm)
(COMMON)
2901 Ignition Unit
(7 cm)
A3299HC
COVER
REF
1575E
1576E
A3299HC
CHASSIS
REF
2
1557E REF
2
1
1574E
Item Description
A1673E2 Kit Electric Parts for 2901EB/EE
1203EEE Cord 10A/220V Cont Europe Plug
1202EEE Cord 13A/220V BS Plug
2000E Transformer, 120/240 VAC 24V
XB0010 1/8ID Shrink Tubing Black
34E2 Cord w/ 115VAC Plug 18-3SJT
A3299HC Box Assembly, Ignition Unit 115V
A3299HC2 Box Assembly, Ignition Unit 230V
2005E Strain Relief Pigtail Black
2005E2 Strain Relief Pigtail Black, for 230V
139E21 Fuse 3AG Slo-Blo 250V 5.0 Amp (115V units)
139E8 Fuse 3AG Slo-Blo 250V 2.5 Amp (230V units)
1157E Fuse Holder, 3AG x 1/4 Tab
SA1332RP04 6-32 x 1/4 RHMS Phillips 18-8
18
Caution!
For continued protection against possible hazard, replace fuses with same type and rating of fuse.
Parr Instrument Company
Page 19
1108P Oxygen Combustion Vessels
Parts for the 1825 Oxygen Filling Connection
1825 Oxygen Fill Connection
Item Description
4VB3 Packing gasket
6VBBB Packing cover, brass
8VB2 Packing nut
9VB1 Union nut, brass, CGA540
20VB Valve seat, PCTFE
21VBBB Lantern ring, brass
53A Oxygen gage, 3-1/2”, 0-60 atm
112VB4AK Valve needle
124VB Union nipple, brass, CGA540
A140VB Toggle relief valve
A150VB Valve knob
188A2 Filling connection body, bare
243VB Tube connector, male
438VB Elbow connector, 45°, male
A476A3 Slip connector with O-rings
394HCJE O-ring for A476A3 slip connector (2 required)
HX0012TB024 Pressure tubing, 1/8” OD, Nylon, 5-ft
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418M R07 10/10/14
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