Parr Instrument 6725 - Manual (Page 19)

6725
Semi-micro Calorimeter Instruction Manual
3-1
QUICK START
Detailed Instructions for preparing the sample and charging the 1109A Oxygen Bomb
are given in Operating Instructions Manual No. 492M. 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. Note the parameter changes in the Operation section
of this manual.
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 subsequent testing.
2. Turn on the stirrer motor switch on the 6725 calorimeter.
3. Prepare and weigh the sample to 0.0001g. Charge the oxygen bomb as described in
manual 492M. 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 Dewar with water to the nearest multiple of 50 milliliters (grams) which just
covers the small hole (gas inlet/outlet) on the bomb head inlet valve. This will be
either 400 or 450 mL of water.
5. Attach one of the ignition wires to the central terminal on the bomb head and push it
down as far as it will go. Attach the second wire to the socket provided on the bomb
hanger. Set the bomb in the loop of the A67C2 bomb support and carefully lower it
into the Dewar to hang from the top rim of the flask. Position the bomb so that the
stirrer can operate freely without striking the bomb. Check for gas bubbles.
6. Close the calorimeter cover and turn on the stirrer motor in the Calorimeter Operation
menu.
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 ID number, sample ID number, sample weight and spike weight in accordance
with the instructions set into the operating controls page.
8. The thermometer will now take over and conduct the test. During the time it is
establishing the initial equilibrium, it will display PREPERIOD on the status bar. Just
before it fires the bomb, it will sound a series of short beeps to warn the user to move
away from the calorimeter. Once the bomb has been fired, the status bar will display
POSTPERIOD. The calorimeter will check to make certain that a temperature rise
occurs and will then look for the final equilibrium conditions to be met. If it fails to
meet either the initial or final equilibrium conditions, or if it fails to detect a
temperature rise within the allotted time, the calorimeter will terminate the test and
advise the user of the error.