Figure 4-4. Set-up for Testing Check Valve
4.9.4 REASSEMBLY (Refer to Figure 5-6).
4.10.3 CLEANING AND INSPECTING PARTS. Clean
and inspect the parts of the check valve assembly as
a. Install rupture disc (3), disc ring (2) and ring
follows:
retainer cap (1) In shorter arm of fitting housing (6).
a. Wash all parts in dry-cleaning solvent (Federal
Tighten ring retainer cap with a torque of 300 pound
Specification P-S-661).
Do not soak parts.
Dry
inches. Loosen and retighten cap three times.
thoroughly with clean, filtered, compressed air or
b. Slip O-ring packing (5) on filter cap (4). Screw
filter cap into fitting housing (6). Tighten filter cap with a
b. Inspect parts for evidence of damage and wear
torque of 375 pound-inches. Loosen and retighten cap
such as stripped screw threads, scratches and scoring of
three times.
finished surfaces, nicks and burrs on valve surfaces.
c. Use 20 gage (0. 032 inch diameter) Monel wire
c. Check poppet return spring for deformation and
to safety caps to fitting housing.
damage. Spring must be cylindrical in shape with ends
closed and square. Free length of spring should be
4.9.5 INSTALLATION. (Refer to Figure 5-3). Install
0.396 0.005 inch.
safety fitting assembly on union (58) in accordance with
instructions in paragraph 4.5.7. Reconnect valve-to
d. Discard all damaged, worn, and questionable
safety-fitting connecting tube (54) to safety fitting
parts.
assembly.
4.10.4 REASSEMBLY (Refer to Figure 5-7).
4.10 CHECK VALVE ASSEMBLY
a. Apply a thin film of pneumatic system grease
(Specification MIL-L-4343) to threads of body screw (2).
4.10.1 REMOVAL. The check valve is mounted on the
outlet fitting of the back pressure valve (see Figure 1-3).
b. Install poppet guide (8), spring (7), poppet (6),
To remove the check valve (see Figure 5-3):
seat retainer (5) and valve seat (4) in valve body (9).
c. Position O-ring packing (3) in groove of body
a. Disconnect dryer-to-tee connecting tube (31)
screw (2). Screw body screw into valve body (9) and
from nipple (32) installed in tee (34).
tighten with a torque of 600 25 pound-inches.
b. Unscrew nipple (35), together with nipple (32),
valve (33) and tee (34) from outlet port of check valve.
4.10.5 TEST. Test the reassembled check valve as
Remove tube fitting gasket (36) from nipple.
follows:
c. Unscrew check valve from outlet fitting of back
pressure valve. Remove tube fitting gasket (5-7, 10)
a. Install check valve in test set-up as shown
from back pressure valve.
schematically in Figure 4-4, except reverse valve so
free flow arrow points toward air supply.
4.10.2 DISASSEMBLY. Disassemble the check valve
assembly in accordance with the exploded view, Figure
5-7.
31
