Parr Instrument 6100 - Manual (Page 20)

5
Operating Instructions
P a r r I n s t r u m e n t C o m p a n y 18
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5
Operating Instructions
Operating the 1108P Oxygen Combustion Vessel
Detailed instructions for preparing the sample and
charging the 1108P Oxygen Combustion Vessel are
given in Operating Instructions No. 418M. Follow
these instructions carefully, giving particular atten-
tion to the precautions to be observed in charging
and handling the bomb.
Operating the Filling Connection
To fill the bomb, connect the hose to the bomb inlet
valve and push the O2 Fill button on the calorimeter
control panel. The calorimeter will then fill the bomb
to the preset pressure and release the residual
pressure in the connecting hose at the end of the
filling cycle. It will take approximately 60 seconds to
fill the bomb. During this time a countdown timer
on the O2 fill button will display the remaining fill
time. Pushing the O2 key a second time will stop the
flow of oxygen at any time. Once the display returns
to its normal reading, the user can disconnect the
coupling and proceed with the combustion test.
If the charging cycle should be started inadvertently,
it can be stopped immediately by pushing the O2 fill
key a second time.
During extended periods of inactivity, overnight
or longer, close the tank valve to prevent leakage.
When changing oxygen tanks, close the tank valve
and push the O2 FILL key to exhaust the system. Do
not use oil or combustible lubricants on this filling
system or on any devices handling oxygen under
pressure. Keep all threads, fittings, and gaskets
clean and in good condition. Replace the two
394HCJE O-rings in the slip connector if the connec-
tor fails to maintain a tight seal on the bomb inlet
valve.
The recommended filling pressure is 450 psig (3
MPa or 30 bar). This pressure is prescribed by most
of the standard bomb calorimetric test methods.
Higher or lower filling pressures can be used, but
the bomb must never be filled to more than 600
psig (40 atm).
Operating the Calorimeter
All operations required to standardize the 6100 Calo-
rimeter, or test an unknown sample, should proceed
step-wise in the following manner:
1. Allow at least 20 minutes for the calorimeter to
warm up. The bomb parts should be wetted and
then dried in the manner used at the conclusion
of a test. This serves to wet all sealing parts as
well as leaving the bomb with the same amount
of residual water which will exist in all subse-
quent testing.
2. Prepare and weigh the sample to 0.0001g.
Charge the oxygen bomb as described in the
Operating the Filling Connection Section. Using
an additional bomb and bucket can increase the
throughput of the 6100 Calorimeter. With this
arrangement, the calorimeter can operate almost
continuously since the operator will be able to
empty a bomb and recharge it while a run is in
progress. A bomb and bucket for the next run will
be ready to go into the calorimeter as soon as it
is opened. Each bomb and bucket combination
will have to be standardized separately and the
proper energy equivalent for each set must be
used when calculating the heat of combustion.
3. Fill the calorimeter bucket by first taring the dry
bucket on a solution or trip balance; then add
2000 (+/- 0.5) grams of water. Distilled water is
preferred, but demineralized or tap water con-
taining less than 250 ppm of dissolved solids
is satisfactory. The bucket water temperature
should be at or slightly below (1-2 degrees) be-
low the room temperature. It is not necessary to
use exactly 2000 grams, but the amount selected
must be duplicated within +/- 0.5 gram for each
run. Instead of weighing the bucket, it can be
filled from an automatic pipet, or from any other
volumetric device if the repeatability of the filling
system is within +/- 0.5 mL.
To speed and simplify the bucket filling process,
and to conserve water and energy, Parr offers a
closed circuit Water Handling System (No. 6510).
This provides a water supply, cooled to the starting
temperature and held in an automatic pipet ready
for delivery in the exact amount needed to fill the
bucket, at a repeatable temperature. Instructions
for this automatic system are given in Operating
Instruction No. 454M.