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|  MIL-E-82886(OS)
DRCL). Total weight of dead weight, holding screw, and durometer shall be 1065 g. The test specimen
shall be placed under the durometer pointer with the pointer resting on the surface of the sample. Release
the lock (called a "Pawl"). Do not permit the point to shock the sample. Record the instrument dial
reading 30 seconds after release, using a stopwatch to measure the time. Determine three values each on
the top and the bottom of the specimen. Record the average of the top average and the bottom average as
the test value.
4.6.4 Vacuum stability test.
4.6.4.1 Capillary tube method. The capillary tube method of the vacuum stability test shall be
carried out in a sealed glass unit (see Figure 1). These tubes shall be calibrated before use and shall
contain a volume of approximately 10 mL. One millimeter (mm) (nominal) capillary bore Pyrex (or
equivalent) tubing shall be used for the manometer. The vacuum stability test chamber is a constant
temperature block that accurately maintains a temperature within 0.5C.
a.
Calibration. The volume of the hot zone shall be found by adding water from a burette to the
open end of the sample tube until the water level reaches the height of the upper edge of the
horizontal capillary tube (the point where the sample tube is to be sealed) allowing water to
flow into the capillary tube to the 102 mm mark.
b.
Reference. This volume of water in mL represents the volume of the hot zone for use in the
calculations of 4.6.4.1e. Make a zero reference mark on the capillary tube 820 mm up from the
bottom of the 920 mm vertical section. The apparatus shall be thoroughly dry before the test
procedure is started.
c.
Preparation. Introduce 4.0 mL of mercury into the cup at the base of the capillary tube and
connect a vacuum line to its mouth. Evacuate the tube to approximately 1 mm of mercury.
Remove the vacuum supply and allow the mercury to enter the capillary.
d.
Procedure. Place the sample tube containing a 0.2 to 0.3 g specimen, weighed to the nearest
0.5 mg, into the stability block after an initial room temperature reading and barometer reading
have been recorded. After the specimen has been in the block 1 hour, take a reading; then take
a final reading 48 hours after the first reading. The difference in mm shall be corrected for
changes in barometric pressure between the beginning and end of the test.
e.
Calculation. All calculations shall be corrected to standard temperature and pressure (STP).
Calculate the volume of gas evolved per gram of specimen as follows:
(ξ) (ψ (ζ)
)
ς
ω
where:
V = mL gas/gram specimen/48 hours at 100C
x = Volume of hot zone (mL)
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