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High and low temperature operation |
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|  MIL-V-18318B
High and low temperature operation - A pressure of 1800 psi
4.7.6
shall be applied to the inlet of the pressure regulating valve. The valve shall then be
subjected to a temperature of 160 5F for 3 hours. After the conditioning period and
while still at this temperature, the valve shall be subjected to and pass the outlet
pressure test. The valve shall then pass the requirements specified in 3.7.5. The valve
shall then be returned to room temperature and shall be subjected to and pass the
leakage test and the pressure and flow test. The above test procedure shall be repeated
utilizing a temperature of -65
5F for 3 hours. After the conditioning period and
while still at this temperature, the valve shall be subjected to and pass the outlet
pressure test. The valve shall then pass the requirements specified in 3.7.5. The
valve shall then be returned to room temperature and subjected to and pass the leakage
test and the pressure and flow test.
4.7.7
Vibration - A pressure of 1800 psi shall be applied to the inlet
of the pressure regulating valve. The valve shall then be vibrated for six hours at a
frequency from 300 to 3000 cycles per minute and a double amplitude of 0.018 to 0.020
inches. The valve shall be cycled six times, each cycle being one hour, and consisting
of varying the frequency from 300 to 3000 and back to 300 cycles per minute. The
valve shall be mounted in each of the three mutually perpendicular axes of vibration
for a two hour period in each plane. During the vibration period, a flow of 30 5
liters per minute shall be maintained through the valve, The valve shall pass the
requirements specified in 3.7.6. The valve shall then be subjected to and pass the
leakage test and the pressure and flow test.
4.7.8
Endurance - The valve shall be connected to a 1800 psi oxygen
pressure source. The inlet pressure to the valve shall be varied from 1800 psi to 300 psi
by means of a suitable cycling device or control valve. This shall constitute one cycle.
The length of the cycling period shall be a minimum of 60 seconds. During the cycling
period, an outlet flow of 30 liters per minute shall be maintained through the valve.
The valve shall be subjected to a minimum of 1000 cycles. Upon completion of this
test procedure, the valve shall be subjected to and pass the leakage and the pressure
and flow tests.
4.7.9
Oxygen bomb test - The valve assembly shall be subjected to
oxygen bomb tests to determine compatibility of the item with high pressure oxygen.
4.7.9.1
Equipment - The equipment used in performing these tests
shall be in accordance with Figure 2. The main valve shall be a rapid-opening 1/4
inch valve, shall require no internal lubrication for operation, and shall be rated for
at least 3,000 psi operation. The valve shall be leak tight when closed and shall open
with such rapidity that at least 95 percent of the total pressure rise shall have occurred
within the test chamber in 20
7 milliseconds. The pressure rise time may be determined
15
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