Parr Instrument 6100 - Manual (Page 24)

5
Operating Instructions
P a r r I n s t r u m e n t C o m p a n y 22
Explosives and High Energy Fuels
The 1108P and 1108PCL vessels used in the 6100
Calorimeter have been designed to provide highly
automated testing of routine samples. Materials
which release large volumes of gas which detonate
with explosive force or burn with unusually high
energy levels should not be tested with these
bombs.
Rather, they should be tested in a model 1104 High
Pressure Oxygen Combustion Vessel designed
specifically for these types of samples.
Volatile Sample Holders
Volatile samples can be handled in a Parr 43A6
Platinum Capsule with a spun rim, or in a Parr 43AS
Alloy Capsule which has a sturdy wall with a flat
top rim. These holders can be sealed with a disc of
plastic adhesive tape prepared by stretching tape
across the top of the cup and trimming the excess
with a sharp knife. The seal obtained after pressing
this disc firmly against the rim of the cup with a flat
blade will be adequate for 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. The 3M
Transparent Tape can be ordered through Parr, 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 deter-
mination. The approximate Heat of Combustion of
the tape is 6300 cal/g. An actual amount should be
determined by running a blank test with tape alone
using a sample weighing 1.0 gram. The compensa-
tion for heat of tape may be done through the spike
option; see Spike Controls, Line 2 - Heat of Combus-
tion of Spike.
Note: Tape should always be stored in a
sealed container to minimize changes in its
moisture and solvent content.
Figure 5-5
Combustion Capsule with Adhesive Tape Seal
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 (see Figure
5-5).
• Puncture the tape at a point below the flag, then
re-weigh the empty cup with its tape cover.
• Add the sample with a hypodermic syringe;
close the opening with the flag and re-weigh the
filled cup.
• Set the cup in the capsule holder and arrange
the auxiliary fuse so that it touches the center of
the tape disc.
• Just before starting the test, prick the disc with
a sharp needle to make a small opening which
is needed to prevent collapse of the disc when
pressure is applied.
• Fill the bomb with the usual oxygen charging
pressure.
• The calorimeter will fire the bomb and complete
the test in the usual manner.