MIL-PRF-25961H
3.6 Environmental conditions. The valve shall operate in the following conditions:
a. Temperature: -65° to 260°F.
b. Vibration: An acceleration power spectral density (APSD) of 0.04 g²/Hz from
15 to50 Hz, and then an increase at a rate of ± 4 dB per octave 300Hz. Also,
an APSD of 0.3 g²/Hz from 300 to 1,000 Hz, and then a decrease at a rate
6 dB per octave to 2,000 Hz.
3.7 Performance.
3.7.1 General. The valve shall be automatic type that controls liquid and gaseous oxygen
flow during filling and operation of LOX converters in the fill, vent, and buildup circuits of 70
and 300 psig LOX systems.
3.7.2 Operating positions. The valve shall have two operating positions: buildup (closed)
and fill-vent (open). When the CRU-59/E valve is disconnected, or connected but not rotated to
full engagement, the CRU-50/A valve shall be in the buildup position. When the CRU-59/E
valve is connected and rotated clockwise to full engagement, the CRU-50/A valve shall be in the
fill-vent position. The required flow patterns for each position are shown in Figure 6.
3.7.3 Cleanliness. All surfaces shall be free of visible particulates (50 microns and
larger), free of visible fluorinated lubricants, and free of hydrocarbon contamination to a level
not greater than 3 milligrams per square foot (mg/ft²) (see 6.6).
3.7.4 Fill check element. The fill check element in the fill outlet port shall prevent a
reverse flow through the fill inlet port in excess of 0.25 standard liter per minute (SLPM) (see
6.4) when a pressure of 70 psig is applied to the fill outlet port and the CRU-59/E valve in fully
engaged.
3.7.5 Leakage.
3.7.5.1 Fill inlet port and vent port back pressure leakage. Leakage from the fill inlet and
vent ports shall not exceed 0.02 and 0.04 SLPM, respectively, when the gas port is plugged, the
cap is removed from the fill inlet port, and pressures of 10 inches of water, 70 psig, and 300 psig
are applied to the fill outlet and the buildup ports.
3.7.5.2 Gas port leakage. The leakage from the gas port shall not exceed 0.25 SLPM
when the vent and fill outlet ports are plugged and a pressure of 30 psig is applied to the buildup
port and through the CRU-59/E valve into the fill inlet port.
3.7.5.3 Mating valve leakage. The CRU-50/A valve shall not leak LOX when fully
engaged with the CRU-59/E valve.
3.7.6 Flow rate.
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