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|  MIL-V-24694(SH)
3.4.1 Preformed packing (O-rings). O-rings shall be fluorocarbon rubber
in accordance with MIL-R-83485 and MIL-R-83485/l.
3.4.2 Special tools. Valves shall be adjustable throughout the pressure
range without the use of special tools. The adjustment type, either external or
internal, shall be as identified in the applicable specification sheet (see 3.1).
(Special tools are those tools not listed in the Federal Supply Catalog, copies
of which may be consulted in the Office of the Defense Contract Administration
Services Management Area (DCASMA)).
3.4.3 Safety. Hand-adjustable threaded parts subject to tampering shall
be securely locked by safety wiring or self-locking nuts. Safety wire shall be
applied in accordance with MS33540 and shall conform to MS20995. Star washers,
lock washers and jam nuts shall not be used as locking devices. Internal
fasteners shall have features which prevent them from coming loose and inter-
fering with system operation.
Valves shall perform as specified in 3.5.1 through
3.5 Performance.
3.5.10.
3.5.1 Operating pressure. The valve shall wet the requirements specified
herein at operating pressures specified in the applicable specification sheet
(see 3.1).
3.5.2 Rated flow. Rated flow shall be in accordance with the values shown
on the applicable specification sheet and shall occur at a differential pressure
not greater than that shown on figure 1 for any nominal set pressure.
3.5.3 Proof pressure. The valve shall withstand a proof pressure of 69 bars
without external leakage, failure, or permanent set (see 4.7.2). If
(1000
a spring is used that permits a pressure setting beyond 35 bars (500
the
proof pressure shall be 200 percent of the maximum pressure setting.
3.5.4 Internal leakage.
3.5.4.1 Reseat. For any pressure settling throughout the applicable operating
range, the valve shall reseat at not less than the minimum reseat pressure shown
on figure 1. The valve is considered to be reseated when leakage does not exceed
that specified In the applicable specification sheet (see 3.1).
3.5.4.2 Leakage. As pressure is decreased after reseating, the leakage shall
not exceed 1 milliliter (mL) per minute at a pressure equivalent to 75 percent of
the set pressure. With pressure Increased from zero to the minimum reseat pressure,
the leakage shall not exceed 1 mL per minute.
3.5.5 Endurance. The valve shall show no sign of damage to the seating sur-
face, instability, or leakage in excess of twice the amount specified in the appli-
cable specification sheet (see 4.7.7).
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