MIL-PRF-25961H
4.6.3 Fill check element leakage. A pressure of 70 psig shall be applied to the fill outlet
port of the CRU-50/A valve. A CRU-59/E valve shall be connected to the fill inlet port of the
CRU-50/A valve. While maintaining 70 psig, the reverse flow through the CRU-59/A valve shall
not exceed 0.25 SLPM.
4.6.4 Fill inlet port and vent port back pressure leakage. The gas port shall be plugged
and the cap shall be removed from the fill inlet port. Pressures of 10 inches of water, 70 psig, and
300 psig shall be applied in steps for a minimum of 2 minutes each to the fill outlet and buildup
ports. While maintaining the specified pressures at each step, the leakage from the fill inlet and
vent ports shall not exceed 0.02 and 0.04 SLPM, respectively.
4.6.5 Gas port leakage. A CRU-59/E valve shall be connected to the fill inlet port of the
CRU-50/A valve. Then the vent and fill outlet ports shall be plugged. A pressure of 30 psig shall
be applied for a minimum of 2 minutes to the buildup port and through the CRU-59/E valve into
the fill inlet port. While maintaining 30 psig, the leakage from the gas port shall not exceed 0.25
SLPM.
4.6.6 Mating valve leakage. A CRU-59/E valve shall be connected to the fill inlet port of
a rigidly mounted CRU-50/A valve. With a constant 30 psig flow of LOX being maintained
through the valves, the following tests shall be performed. First, a force of 13-pounds shall be
applied at the rear (hose connection) of the CRU-59/E valve in a direction perpendicular to the
charging hose (major axis of the valve) in all four 90° quadrants. Next, a force of 13-pounds then
shall be applied at the rear (hose connection) of the CRU-59/E valve in line with the charging
hose to establish a pull on the mating valve surfaces. No LOX leakage shall occur from the
CRU-50/A valve.
4.6.7 Fill cycle flow rate. The pressure drop through the CRU-59/E valve, as installed on
a test apparatus, shall be measured at a flow of 40 SLPM with the fill poppet stem held
depressed. The CRU-50/A valve shall be mated with the CRU-59/E valve, and the pressure drop
shall be measured at the same specified flow from the fill outlet port. The difference in pressure
drop shall not exceed 2.4 psig.
4.6.8 Vent cycle flow rate. A CRU-59/E valve shall be connected to the fill inlet port and
a pressure of 34 inches of water shall be applied to the gas port. The flow from the vent port shall
be a minimum of 70 SLPM.
4.6.9 Buildup cycle flow rate. A pressure of 21 inches of water shall be applied to the
buildup port. The flow from the gas port shall be a minimum of 40 SLPM.
4.6.10 High temperature exposure. The valve shall be exposed to 260° ± 2°F for a
minimum of 4 hours. The valve then shall be subjected to tests in 4.6.3 through 4.6.5.
4.6.11 Low temperature exposure. The valve shall be exposed to -65° ± 2°F for a
minimum of 4 hours. The valve then shall be subjected to tests in 4.6.3 through 4.6.5.
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