MIL-DTL-24630A(SH)
4.6.4.2 Cracking pressure. Gradually increasing pressure shall be applied in the free-flow direction beginning
with zero pressure. Cracking pressure shall be observed and shall be not less than 2 lb/in² or greater than 8 lb/in²
(see 6.5.1).
4.6.5 Temperature extremes. The fluid for the temperature functioning tests shall be in accordance with
MIL-DTL-17111 or MIL-PRF-5606.
4.6.5.1 Low temperature functioning. The valve shall be connected to a static head of 1 to 3 feet of fluid in the
reverse-flow direction. This arrangement shall be maintained at a temperature not warmer than -22 °F (-30 °C) for a
period of at least 16 hours. After this period, the valve shall be actuated mechanically five times. After the fifth
actuation, the leakage test (qualification) of 4.6.3.1 shall be performed at -22 °F (-30 °C), and the requirements
therein shall be satisfied. Checking time and cracking pressure tests of 4.6.4.1 and 4.6.4.2, respectively, shall then
be performed at -22 °F (-30 °C) and the requirements of those tests shall be satisfied.
4.6.5.2 Rapid warm-up. The low temperature arrangement shall be warmed rapidly until the fluid temperature
reads 194 °F (90 °C). While the temperature is being raised, the valve shall be mechanically actuated at
approximately 68 °F (20 °C) increments of fluid temperature rise to determine proper operation as specified in
4.6.5.3 High temperature functioning. The following tests shall be conducted at a temperature of 194 °F
(90 °C). With a head of 1 to 3 feet of fluid on the valve in the reverse-flow direction, the poppet shall be actuated
mechanically 10 times. After the tenth actuation, the leakage test (qualification) of 4.6.3.1 shall be conducted and
the requirements therein shall be satisfied. Checking time and cracking pressure tests of 4.6.4.1 and 4.6.4.2,
respectively, shall then be performed and the requirements therein shall be satisfied.
4.6.6 Endurance. The valve shall demonstrate 50,000 MCBF at a working pressure of 3,000 lb/in² with the test
fluid contaminated to Class 10 of SAE-AS4059 prior to starting the test. The valve shall be rechecked and
additional contaminant added every 12,500 cycles. Test fluid contamination levels shall be determined by the
method specified in SAE-AS598. Each cycle shall consist of imposing not less than one half of the rated flow
(see 3.1) in the free-flow direction through the valve followed by reducing the pressure to zero. Cycling shall be at a
rate not to exceed 30 cycles per minute. There shall be no chatter or surging during the test. The leakage test
(qualification) of 4.6.3.1 shall be conducted at 25, 50, 75, and 100 percent of the required cycles, and the
requirements therein shall be satisfied. At the conclusion of the test, the checking time and cracking pressure tests
of 4.6.4.1 and 4.6.4.2, respectively, shall be performed and the requirements therein shall be satisfied. Following the
test, the valve shall be disassembled and examined as specified in 4.5.1.1 and 4.5.1.2. Any evidence of distortion,
physical damage or abnormal wear shall be cause for rejection.
4.6.7 Fatigue impulse test. One or more assemblies shall be subjected to a fatigue rating verification test as
specified in 3.5.9. A photograph shall be taken showing the actual impulse curve, as indicated by oscilloscope (or
equivalent method).
4.6.8 Salt spray. The valve shall be subjected to the salt fog (corrosion) test as specified in Method 509 of
MIL-STD-810. Following the test, the valve shall be disassembled and examined for evidence of corrosion on metal
parts. Any evidence of surface corrosion shall be cause for rejection. The salt fog test shall not be required if the
valve body is constructed of material specified in 3.3.1, 3.3.1.1, and 3.3.1.2. For other body materials, the salt fog
test may be waived, but only at the discretion of NAVSEA. When more than one design is developed by the same
contractor who uses the same method of surface preservation for all designs, only one representative unit shall
require this test, provided the same materials are used. Test data on similar equipment with the same base, coating
materials, and equivalent coating thickness may be used to meet this requirement.
4.6.9 Vibration. The valve shall be subjected to and pass the vibration tests as specified in 3.5.11. Following
the vibration test, the valve shall be subjected to the leakage test (qualification) of 4.6.3.1 and the requirements
therein shall be satisfied. The valve shall also be examined as specified in 4.5.1.1 and 4.5.1.2 and the requirements
therein shall be satisfied. Any sign of external or internal damage shall be cause for rejection.
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