TM 10-4320-317-13
5-6. MAINTENANCE OF MAIN VALVE ASSEMBLY - (Cont)
WARNING
To prevent injury to personnel, be sure to vent internal pressure from pressure-reducing valve
before disassembling valve. Water released under pressure may cause injury to personnel.
(1)
Remove nuts (1) from cover (3).
(2) Using dull cold chisel, drive upward around edge of cover (2) to loosen.
WARNING
Remove cover slowly to release tension on spring. Sudden release of spring tension may cause
injury to personnel.
CAUTION
Pull cover straight up, to avoid damaging cover bearing or valve stem.
(3) Slowly lift cover (3) from valve body (4). Remove stud spacers (5).
(4) Remove spring guide (6), spring (7), and spacer (8) from valve stem (9).
(5)
Lift assembled diaphragm (12) and disc (14) components from seat (16). Remove spacers (15).
CAUTION
To prevent damage to stem, be sure to use vise that has soft brass jaws.
(6)
Secure lower end of valve stem (9) (on diaphragm and disc assembly) in vice with soft jaws.
(7)
Examine threads above stem nut (10) for signs of corrosion or mineral deposits. If needed, clean
threads with wire brush before removing nut.
(8)
Remove stem nut (10).
(9)
Remove diaphragm washer (11), diaphragm (12), disc retainer (13), and disc (14) from valve stem (9).
(10) Pry disc (14) from disc retainer (13). Remove disc (14).
c.
INSPECT (Figure 5-3).
(1) Inspect threads for damage. If thread are damaged, replace main valve body (4).
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(2) Inspect seating surface on valve body. If worn, replace valve body (4).
(3)
Inspect valve stem (9) for corrosion and scale. If needed, use crocus cloth moistened with water to
clean valve stem.
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