MIL-DTL-23953D(SH)
3.6.2 Cracking/reseating pressures. The check poppet shall begin opening before the pressure differential (inlet
to outlet) across the valve exceeds 20 pounds per square inch (psi), and shall be fully closed at or before 7 psi
pressure differential on decreasing inlet pressure (see 4.4.9).
3.6.3 Vent capacity. The vent feature shall vent pressure in an upstream volume from 100 to 25 psig in a time
not greater than 2.7 seconds per 100 cubic inches of upstream volume (see 4.4.12).
3.6.4 Check poppet tightness. With a closing pressure differential (outlet to inlet) of anywhere between zero
and 4,500 psig, there shall be no visible leakage past the check poppet (see 4.4.8).
3.6.5 Vent valve tightness. With the check valve open, leakage through the vent port, at upstream pressures
anywhere between zero and 4,500 psig, shall not be greater than 0.05 pound mass per second [(lbm/sec) (39.6
standard cubic feet per minute (scfm)] (see 4.4.7).
3.6.6 Check poppet stability. Valves shall operate without chatter or instability at all flow rates above
400 cubic feet per minute (ft³/min). Packing on the check poppet stem, or other means to improve stability which
could adversely affect the functional reliability of the valve, shall not be used (see 4.4.15).
3.6.7 External leakage. There shall be no external leakage except that allowed from the vent port (see 3.6.5)
when tested as specified (see 4.4.10).
3.6.8 Mechanical shock and vibration. Valves shall meet the mechanical shock requirements of Grade A,
Class I, of MIL-S-901 and the environmental vibration requirements of Type I of MIL-STD-167-1 (see 4.4.19 and
3.6.9 Underwater explosion shock. When installed in a test fixture which represents the most vulnerable
shipboard installation and subjected to two shots of 125 pounds of HBX-1 underwater explosions as described in
4.4.18, the valves shall maintain the integrity of the pressure boundary and retain the performance requirements
3.6.10 Water-slug. Valves shall withstand the transient shock pressure conditions that can result when the
piping upstream of the valve is completely flooded with water and then subjected to 4,500 psig air by way of a quick
opening valve. The valve shall meet the requirements of the water-slug test as specified (see 4.4.17).
3.6.11 Needle assembly tightness. The needle assembly shall be capable of holding 6,750 psig of water
pressure without leaking. The valve shall meet the requirements of the needle assembly test as specified (see 4.4.6).
3.6.12 Durability. Valves shall withstand a minimum of 5,000 cycles without signs of damage, wear, or
degradation of operability. The valve shall meet the requirements of disassembly and examination (see 4.4.3) after
3.7 Marking.
3.7.1 Body markings. A flow arrow shall be cast or forged integral with the valve body as specified in
803-8436621.
3.7.2 Identification plates. Each valve shall have a permanently attached identification plate as specified in
803-8436621.
3.7.3 Manufacturer s traceability numbers. In accordance with 0948-LP-045-7010, a unique traceability
number shall be marked on all parts designated as "Level I" on 803-8436621 (see 6.2). All parts identified as
"Level I" on 803-8436621 shall be marked and directly traceable to certification data attesting to the chemical
composition and mechanical properties for each piece (i.e., heat number, heat-treat number/or lot number, as
applicable, in accordance with material specification). The following information shall be provided on all
permanently marked material:
a.
Type of material (in accordance with the material specification).
b.
Traceability number.
Manufacturer s name, trademark, or symbol.
c.
3.7.4 Radiography marking. Radiographed components shall be legibly and permanently marked "RT".
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