Parr Instrument 1122 - Manual (Page 2)

1121 & 1122 Oxygen Combustion Vessel
P a r r I n s t r u m e n t C o m p a n y 2
Closing the Bomb
Before closing the bomb, check the head gasket to be
sure that it is in good condition and moisten it with a
few drops of water; then push the head firmly into the
cylinder. Slide the clamping rings into position and raise
the band from the bottom of the bomb to encircle the
rings. Position the band so that its cone pointed screw
enters the dimple drilled in the outer face of one of the
ring sections, then tighten the screw. Seal the bomb by
tightening each of the cap screws, applying a firm, hard
pull to the wrench supplied with the bomb. Or, if a torque
wrench is available, apply 25 ft-lbs to each screw. Tight-
ening should proceed in a criss-cross pattern rather than
progressively around the circle.
Filling the Bomb
All of the fittings needed to charge the bomb with oxy-
gen from a commercial oxygen cylinder are provided in
a Parr 1825A Oxygen Filling Connection. As an alternate,
the bomb can be filled by purchasing only the A19A7
hose assembly used on the 1825 filling connection and
attaching this hose to a standard pressure regulator on
the oxygen tank. The threaded coupling needed for the
bomb inlet connection is furnished with the A19A7 oxy-
gen hose.
To fill the bomb, attach the hose to the inlet valve, open
the valve on the filling connection slowly and watch the
gage as the bomb pressure rises to the desired filling
pressure. The bomb should not be filled to more than 300
psig (20 atm.) at room temperature. Do not overfill the
bomb. If too much oxygen should accidentally be intro-
duced, do not proceed with the combustion. Detach the
filling hose; exhaust the bomb and refill with oxygen be-
fore igniting the charge.
Firing the Bomb
Recommended practice is to immerse the bomb in wa-
ter when it is fired, however this is not required. It must
always be placed behind a heavy shield or barricade to
protect the operator in case of an accidental explosion.
Set the ignition unit outside the barricade and arrange
the bomb so that the operator will be protected by the
barricade but with the pressure gage visible so that he
can observe the bomb pressure. The bomb must stay be-
hind the barricade during firing and remain there until
there is a definite indication that the peak pressure has
been reached and the pressure is definitely going down.
The pressure will increase rapidly during the first 3 to 5
seconds after firing, after which it may drop slightly, only
to rise again during the next 30 seconds. Most combus-
tions are complete after the first minute, but it is well to
wait at least 2 minutes after firing before handling the
bomb. In all cases, be sure that the pressure is definitely
going down before opening the discharge valve. Always
open the valve slowly and be sure that the operator’s
hand or face are not in line with the discharge.
Firing the 1122 Oxygen Combustion Vessel
The mass of the 1122 Oxygen Combustion Vessel is ap-
proximately 11.2 kg. An energy release of 0.1MJ will raise
the temperature of the unit ~20C. This assumes the heat
capacity of the bomb is about 1/10 that of an equal mass
of water and the heat has sufficient time to distribute uni-
formly.
CAUTION! During the combustion process and
shortly thereafter, the midsection of the cylin-
der immediately above the sample holder will
become quite warm. Take care when handling
the unit after the combustion is complete.
Opening the Bomb
To open the bomb: loosen the cap screws in the split ring
sections then loosen the knurled screw in the outer band
and push the band downward to rest on the table. The
ring sections can now be removed and the head lifted
from the cylinder. Transfer the head to the tripod support
ring, being careful not to bend or disturb the electrode
or sample holder. Normally the 441HC sealing ring will
come out with the head, but if the bomb has been under
pressure for some time the ring may have absorbed oxy-
gen and become swollen, in which case it will drop away
from the head. The gasket will gradually return to its nor-
mal size after the absorbed gas dissipates.
WARNING: Do not overcharge this bomb and do
not fi re it if there is any evidence of a gas leak.
The sample weight must not exceed 10 grams
and the charging pressure should not exceed
300 psig, unless cautious experiments show that
a higher charging pressure is required to obtain
complete combustion, and the higher charge
does not produce a peak pressure in excess of
1500 psig at any time during a test. If there is
any reason to suspect that the bomb is leaking,
immerse it in water and check for leaks before
fi ring. Inspect the bomb regularly and replace
any parts which are no longer serviceable or
which show signs of weakness.
Special Procedures
Suggested procedures for handling volatile liquids or
other unusual materials can be obtained by contacting
Parr Instrument Company direct, either by telephone or
correspondence.
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: [email protected]