MIL-PRF-46676B (AR)
4.3.4.3 Procedure. The noisemeter shall be adjusted to zero-out room noise and
determine maximum noise caused by the striker falling 320 centimeters onto a 35 milligram
pellet of inert powder. In any test a reading above this maximum shall be classified as a fire.
The impact machine shall be standardized using Composition B Type II conforming to MIL-C-
401. Approximately 5 grams of Composition B shall be ground and screened on a sieve stack
consisting of a 16 mesh (U.S. Standard) on top, a 30 mesh in the middle, and a 50 mesh on the
bottom. The material remaining on the 16 mesh and the material passing through the 50 mesh
sieves shall be discarded. Equal amounts of material on 30 and 50 mesh sieves shall be
thoroughly mixed. The Composition B shall be made into pellets weighing 35 ± 2 milligrams,
and having a diameter of 0.188 ± 0.002 inches. The pellets shall be pressed at 30,000 pounds per
square inch.
A one inch square of flint paper, 5/0 grade or equivalent, shall be placed on the anvil for each
test. Before the tests are performed the explosion and non-explosion point shall be determined.
After the approximate heights of explosion and non-explosion are determined, the 25 samples
shall be tested as follows: Place the specimen on the flint paper and drop the weight from 40
centimeters or 1.6 log units; if no explosion results raise the striker on tenth log increment at a
time and place a new specimen and paper on the anvil until an explosion occurs, then lower the
striker on tenth log increment until a fresh specimen does not explode. The striker and anvil shall
be cleaned with acetone after each drop and wiped dry with a clean cloth. The height and results
of each drop shall be recorded as follows: An explosion shall be recorded as a plus sign and a
non-explosion as a minus sign.
Summary of Firing Data
a
b
c
b.c
0
1
2
3
4
5
N
A
Where:
a = the drop heights in log increments of 0.1 log unit, beginning with the
lowest drop height at which a test (explosion or non-explosion) was
observed.
b = arbitrary consecutive numbers.
c = the number of tests observed at each corresponding drop height.
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