MIL-DTL-52031E
assembly and shall incorporate a ring pull for easy withdrawal. A self-locking seal, affixed through the
safety pin ring over and around the actuating lever, shall be provided with each extinguisher. The safety
pin shall not allow activation of the extinguisher when a 50 pound force is applied simultaneously against
the outer ends of the valve-opening lever and the carrying handle. Blocks or spacers shall not be used in
conjunction with the safety pin.
3.6.5 Swivel arm. The swivel arm shall be attached to the head assembly. The swivel arm shall have a
vertical swivel from a downward position where the horn touches the cylinder to an upward position in line
with but not exceeding the longitudinal axis of the extinguisher cylinder. A lifting force of not less than 4
foot-pounds or more than 8 foot-pounds applied to the end of the assembly shall be required to produce
angular displacement of the swivel arm. Jarring, vibration, or handling shall not detach the horn from the
swivel arm. The swivel arm shall incorporate a 30 degree bend near the swivel (on the front face
opposite the handle-hold). The sweep may be limited by the cylinder body when the head is attached to
the cylinder body. When in the rest position, the swivel-arm and horn assembly shall not extend beyond
the cylinder bottom.
3.6.6 Grip. When in the operating position, the grip shall be positioned at an angle of 60° ± 5° with the
cylinder longitudinal axis. The grip shall have a breadth of not less than 1 inch, and no sharp edges shall
be exposed. Metal thickness shall not be less than 0.060 inch. The grip shall be provided with finger grip
depressions.
3.6.7 Discharge nozzle and horn. The discharge horn shall reduce the turbulence and direct the
extinguishing agent discharge vapor stream. The discharge horn shall not be less than 3 ½ inches long.
The discharge horn shall be fabricated of tough, water-resistant and heat-resistant material, having a non-
corrosive orifice bushing molded or securely built into the inlet of the horn. The horn material shall have
dielectric strength to withstand for a minute, without breakdown, a voltage of 5000 volts, 60-cycle ac. The
horn shall withstand aging, weathering, and mechanical and thermal shock encountered by operation
within climatic extremes without cracking, appreciable change in flexibility, or evidence of distortion or
other damage. The horn shall be attached to the swivel arm so that no separation occurs during handling
or operation of the extinguisher. The expanding orifice or primary point of expansion of the liquefied
extinguishing agent shall be located in the discharge horn at the point where the horn connects to the
swivel arm.
3.7 Performance. The discharge time for expelling the liquid contents (remaining agent weight less than
10% of label agent weight) of the extinguisher at 68° F shall not be less than 8 seconds and not more
than 12 seconds. The discharge range shall not be less than four feet for the full time the extinguisher is
discharging. The extinguisher shall show no signs of leakage when tested with a leak detector, which will
detect a leakage rate as low as 0.1 ounce or less per year. After the extinguisher has been removed from
the bracket ring and the safety pin has been extracted and the swivel arm adjusted to the proper angle for
use the extinguisher shall be operable by an operator using one hand.
3.8 Climatic extremes. The extinguisher shall operate at any air temperature from -50° F without benefit
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of solar radiation, to +120° F while exposed to a solar radiation intensity of 360 BTU/ft /hour, and shall be
capable of safe storage at temperatures from -80° F for a period of 72 hours to +185°F for a period of four
hours daily.
3.9 Corrosion resistance. The fire extinguisher shall withstand a salt spray for 200 hours without evidence
of corrosion sufficient to impair functioning of the extinguisher or to prevent manipulation of fittings and
connections with regular servicing tools.
3.10 Drop resistance. The fully charged extinguisher shall be operable after being subjected to at least
three drops from a height of not less than four feet.
3.11 Vibration. The extinguisher mounted in the bracket shall withstand vibration forces in the vertical
position at the rate of 60 cps at 1¼ g acceleration forces.
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