F
OR
M
ODELS
: JGI, JGM, JGN, JGP
AND
JGQ
S
ECTION
5 - M
AINTENANCE
PAGE 5-42
tool which is softer than the valve plate material be used or care be exercised to
prevent damage to the plate. A suction valve plate can only be depressed from
the valve fastener (bolting) side of the valve, and a discharge valve plate can
only be depressed from the side of the valve that goes toward the cylinder bore.
Reference Figure 5-29 on page 5-41.
3.
Using the proper valve puller/installation tool, illustrated in Figure 7-1 on page
7-2, the valve and the retainer may be inserted into the pocket together. Be sure
the valve is properly seated in the pocket. When installed correctly the valve
should rotate freely when turned by hand, and the distance from the outer
retainer face to the surface of the valve boss on the cylinder will be 1/8 inch
(3 mm) shorter than the length of the nose on the valve cap.
4.
The retainer keeper is a plastic thumb screw in a threaded hole in the bottom
valve retainers. This should be screwed through just far enough to provide fric-
tion so that bottom retainers will not fall out while the cap is being installed.
5.
Inspect the valve cap o-ring for cuts or gashes and replace it if necessary. Lubri-
cate the o-ring and the nose of the valve cap. Some high pressure cylinders use
a soft metallic wire gasket in lieu of the o-ring design. Insert the cap and tighten
the bolting evenly to the recommended torque in Table 1-12 on page 1-16. See
“Bolt Tightening for Valve Caps” on page 5-42. If the assembly is correct, the dis-
tance from the underside of the cap to the valve boss surface on the cylinder will
be 1/8 inches (3 mm).
NOTE: BE CERTAIN ALL PARTS, GASKET FACES, AND MATING SURFACES ARE
ABSOLUTELY CLEAN AND ALWAYS USE CLEAN, FRESH OIL ON THE
THREADS BEFORE RE-INSTALLING BOLTS.
Bolt Tightening for Valve Caps
Proper fastener tightening technique is essential for sealing of valve caps with soft metallic
wire gaskets used in some high pressure cylinders. It is important to draw up bolting to full
torque in even and gradual steps. Do not allow the valve cap to be tightened with bias on
one bolt or to become cocked in the bore. Such bias or cocking can cause uneven crush of
the gasket, which could cause a leak and could also cause bolt failure. This step tightening
procedure is also recommended for all valve caps.
Valve Cap
Metallic Wire
Gasket
Valve
Retainer
Pre-formed
Metallic
Gasket
Valve
Assembly
F
IGURE
5-31 H
IGH
P
RESSURE
V
ALVE
C
AP
A
SSEMBLY
Install the valve assembly (and high
clearance spacer, when applicable),
with the flat gaskets(s) and valve
retainer, in the valve pocket. See
“Valves - Reassembly” on page
5-41. For high pressure applica-
tions, place a new, proper, soft
metallic wire gasket on the retainer
and install the valve cap. Be careful
not to gouge the bore, distort or
damage the wire gasket. Always use
a new metallic wire gasket; wire gas-
kets are not reusable.
Lubricate threads and bolt seating
surfaces with petroleum type lubricant (except for stainless steel bolting, use a thin coating
