MIL-PRF-46676B (AR)
4.3.2 Detonation Velocity. Two specimens, ¼ by ¼ by 12 inches, shall be attached to a
wooden bar ¼ inch by 1 inch by 9 inches with two 9/32 inch holes 7.871 inches from center to
center. One end of the specimen shall be even with one end of the bar and the other end shall
have a three inch overhang which is used for the starting relay. Chronograph contactors shall be
inserted into the holes of the bar so that they are flush with the explosive. The contactors shall be
connected to an electronic counter which measures microseconds. An M6 blasting cap or
equivalent shall be used to initiate the specimen. If any specimen fails to comply with the
requirement, the lot shall be rejected. NOTE it is important that the lead wires from the
contactors be turned away from the blasting cap so that the initial detonation does not start the
counter. The rate of detonations shall be calculated as follows.
0.2
R=
× 1,000,000
A
Where:
A = time in microseconds
R = rate in meters/second (MPS)
4.3.3 Shock sensitivity. The cylinder case for the drop test shall be constructed of mild
steel with walls of 0.06 inches thick and having internal diameter of 5 inches and a length of 12
inches. The case shall have threaded mild steel caps, 3/8 inch thick. A charge of flexible
explosive shall be pressed so as to fill the case snugly. The case shall be fixed horizontally
beneath a weight of 336 pounds, equipped underneath with 3 equally spaced steel studs (3 inches
long and ¾ inch in diameter) so that when the weight is dropped the studs will penetrate the top
surface of the case. Ten cases shall be tested by dropping the weight on each case from a height
of 5 feet. A blast or explosion shall be cause for rejection, a fire unaccompanied by a blast or
explosion is permissible.
4.3.4 ERL Bruceton impact sensitivity. The Flexible explosive shall be in a powder
form and be able to pass through 20 mesh screen. Twenty five samples having a diameter of
0.188 ± 0.002 inches and a weight of 35 ± 2 milligrams shall be prepared for this test.
4.3.4.1 Impact machine. An ERL-Bruceton type drop test machine with 320 centimeters
maximum drop height equipped with "type 12 tools" and a 2.5 kilogram weight shall be used, or
equivalent.
4.3.4.2 Noisemeter. A peak reading noisemeter consisting of a microphone, amplifier,
and peak reading voltmeter shall be used. The amplifier or voltmeter shall have an adjustment for
zeroing out the background noise. The amplifier of the noisemeter shall be capable of voltage
gain of 50 decibels with provisions for varying the gain. The noisemeter shall have a response
between 100 cycles and 20 kilocycles and shall be equipped with a dynamic type microphone
having output level within -60 decibels to -52 decibels.
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