MIL-V-25675E, MILITARY SPECIFICATION: VALVES, CHECK, MINIATURE, HYDRAULIC, AIRCRAFT AND MISSILE (13 MAY 1968) [S/S BY MIL-PRF-25675B]., This specification covers hydraulic, spring-loaded, normally closed aircraft and missile hydraulicsystem check valves with operating pressures up to 3,000 pounds per square inch (psi) and operating temperaturesfrom -65 deg to 450 deg F.