TM 5-4310-393-14d.Torque the valve head cap screws (15) to 18 lb -ft (25 Nm) before tightening the socket set screw (5)in order to avoid damage to the valve body (10).e.Tighten the socket set screw (5) with the appropriate sized hex key.f.Position the gasket (4) and plain cap nut (3) and tighten it with an open end wrench.g.Reinstall the tube connections (16, 18) and the inlet connection to the valve head (17).4-14.5. VALVE HEAD ASSEMBLY, SECOND STAGE.This task covers: A. Inspect B. ReplaceTools:Materials/Parts:Valve Head Wrench (P/N 004555)GasketsTorque Wrench (P/N 6006NMA)RTV Sealant NSN 8040-00-225-4548Grease (Item 17) NSN 9150-00-754-2760Equipment Conditions:Compressor Secured and ColdAll Air Pressure Purged From SystemA Inspect.1.Second Stage Discharge Valve. Remove and inspect the 2nd stage discharge valve as follows:a.Remove the plain cap nut (Figure 4-10, Item 3) and the gasket (4). Inspect the gasket. The gasketshould be replaced If damaged.b.Unscrew and remove the socket set screw (5) and the discharge valve cover (6).c.Remove the spring washer (7) and the O-ring (8). The O-ring should be undamaged. Replace it ifnecessary.d.Extract the discharge valve assembly (9).e.Discard the valve gasket (14) and replace It with a new gasket.f.Inspect the valve seat (13). The sealing surface must be in good condition: devoid of pitting orcracking. The maximum valve seat width is 0.039" (1.0 mm)g. Clean and inspect the valve plate (12). The maximum acceptable groove depth must not exceed0.008" (0 2 mm).h.Check the tolerance of the inside diameter of the valve body (10). The valve body must not show anygrooves at ID 0 669"-0.673" (17.0-17.1mm).i.The valve spring (11) is reusable if it shows no outside scuffing and the spring coils are not touching.2.Removing the 2nd Stage Inlet Valve. To remove the 2nd stage inlet valve, it is necessary to first removethe valve head. Proceed as follows:4-22
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