Parr Instrument 6772 - Manual (Page 19)

6772
Calorimetric Thermometer Instruction Manual
3-1
QUICK START
The basic operating instructions for the 1341 Calorimeter are found in Operating Instructions
Manual No. 204M. Detailed instructions for preparing the sample and charging the 1108
Oxygen Bomb are given in the operating instructions, manual number 205M. Follow these
instructions carefully, giving particular attention to the precautions to be observed in charging
and handling the bomb. The default values of the 6772 are designed to operate with the
1341 Plain Jacket calorimeter.
1. Allow at least 20 minutes for the thermometer 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 subsequent testing.
2. Turn on the stirrer motor switch on the 1341 Calorimeter.
3. Prepare and weigh the sample to 0.0001g. Charge the oxygen bomb as described in
manual 205M. Using an additional bomb and bucket can increase the throughput of the
1341 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.
4. 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 containing less than 250 ppm of dissolved solids is satisfactory. The bucket water
temperature should be at or slightly below (1-2 degrees) 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.
5. Set the bucket in the calorimeter. Attach the lifting handle to the two holes in the side of
the screw cap and partially lower the bomb in the water. Handle the bomb carefully
during this operation so that the sample will not be disturbed. Push the two ignition lead
wires into the terminal sockets on the bomb head. Orient the wires away from the stirrer
shaft so they do not become tangled in the stirring mechanism. Lower the bomb
completely into the water with its feet spanning the circular boss in the bottom of the
bucket. Remove the lifting handle and shake any drops of water back into the bucket and
check for gas bubbles.
6. Close the calorimeter cover. This lowers the stirrer and thermistor probe into the bucket.
7. Select determination or standardization as appropriate on the Calorimeter Operation page,
by toggling the operating mode key. The calorimeter will now prompt the operator for Bomb