Figure 4-4. Set-up for Testing Check Valve

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

nitrogen.

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.