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|  MIL-V-46727C(AT)
4.7.3.1 Rated flow and pressure drop. To determine conformance to 3.4.1, the rated flow
of the valve shall be accurately maintained at the applicable value specified in 3.4.1. A
manometer, or other accurate means of measuring pressure drop from one port to another, shall
be employed. The pressure drop for valves shall be measured and recorded.
4.7.3.2 Operating torque. To determine conformance to 3.4.2, the valve shall be subjected to
a hydraulic pressure of 3000 psi at the pressure port, the torque required to operate the valve
shall be measured and recorded.
4.7.3.3 Operating pressure. To determine conformance to 3.4.3, the valve pressure shall be
applied to each port, except return, and varied throughout a range of 0 to 3000 psi. Operation
shall be observed and results recorded.
4.7.3.4 Proof pressure. To determine conformance to 3.4.4, the valve shall be subjected to
proof pressures in accordance with 3.4.4 applied at the pressure and return ports for a period of
2 minutes. The valve shall be manually actuated after application of pressures. There shall be
no evidence of external leakage, permanent deformation, or failure. The results shall be
recorded.
4.7.3.5 Burst pressure. After completion of all other tests. the valve shall be subjected to the
pressure specified in 3.4.5 at the pressure ports and return port for a period of 3 minutes at each
application. This test shall be performed for all three positions. When testing pressure ports, the
return port shall be open. The rate of application of pressure shall not exceed 26 000 psi per
minute. The valve need not be operable after these tests. Results shall be recorded to determine
conformance to 3.4.5.
4.7.3.6 Internal leakage. To determine conformance to 3.4.6, the valve shall be tested for
leakage by applying hydraulic pressure of 3000 psi to each sealing member, of individual fluid
chambers, in succession for a 2 minute period each. The pressure shall then be lowered by 5 to
10 psi (gauge) and held for 2 minutes. There shall be no external leakage and the combined
internal leakage from each port shall be recorded.
4.7.3.7 Endurance. To determine conformance to 3.4.7, the valve shall be subjected to
hydraulic pressure of 3000 psi and a rated flow as specified (see 3.4.1), for 20 000 cycles.
Cycling shall be as specified in 3.4.7. The valve shall be observed for evidence of external
leakage during cycling. After cycling, internal leakage shall not exceed the value specified in
3.4.6. The valve shall evidence no excessive wear or breakdown and the results shall be
recorded.
4.7.3.8 High temperature. To determine conformance to 3.4.8.1, the valve shall be placed
within a test chamber and exposed to high temperature as specified in MIL-STD-810,
method 501, procedure II, for a time period of 24 hours. After 24 hours of exposure, valve shall
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