type specification number (see examples listed below).
In most cases for liquid transfer and/or vapor recovery
compressors, the valve type will be spec 3 or 3P.
Model number 491AM 3 FBANSNN
Valve type = spec 3
Model number 691AM 3P FBANSNN
Valve type = spec 3P
Valve Holddown Assemblies: Depending on your model
of compressor, the valve holddown assembly has all or a
combination of the following:
1. Valve cap / cover
2. Valve cap O-ring
3. Holddown screw
4. Valve cover plate
5. Valve cover plate bolts
6. Valve cover plate O-ring
7. Valve spacer (model 491 only)
8. Valve cage
9. Valve assembly
10. Valve gasket
Valve Assemblies: Depending on your valve specification,
the valve assembly has all or a combination of the following:
1. Gasket
2. Adjusting screw
3. Relief ball spring
4. Relief ball
5. Valve seat
6. Valve plate
7. Spacers
8. Washer
9. Valve spring
10. Suction valve post
11. Valve bumper
12. Valve gasket
See valve holddown and valve assembly part details
in the appendix for a complete list of part numbers
and descriptions.
Valve Inspection and/or Replacement for Models
91 and 291 Compressors
Before removing and inspecting the valves, begin by
depressurizing and purging (if necessary) the unit.
Disassembly
1. Unscrew the valve cap and remove O-ring.
2. With the special wrench supplied with your compressor
at time of purchase, remove the holddown screw.
3. After the holddown screw has been removed, the
valve assembly and valve gasket can be lifted out.
4. Carefully inspect for dirt or broken/damaged parts.
5. Inspect valves for breakage, corrosion, debris and
scratches on the valve disc or plate. In many cases,
valves may simply be cleaned and reinstalled. If the
valves show any damage, they should be repaired or
replaced. Replacement is usually preferable although
repair parts are available. If valve plates are replaced,
seats should also be lapped until they are perfectly
smooth. If more than .005 in. must be removed
to achieve a smooth surface, the valve should be
discarded. If plates are replaced without relapping the
seat, rapid wear and leakage may occur.
Assembly
1. Insert metal valve gasket into the suction and/or
discharge opening of the head. The metal valve
gasket should always be replaced when the valve
is reinstalled.
2. Insert cleaned or new valve assembly. Make sure the
suction and discharge valves are in the proper suction
and discharge opening in the head. NOTE: The spec
3 suction valves for a model 91 and 291 compressor
are pre-set so no adjustments to liquid relief pressure
are necessary.
3. Replace the holddown screw and tighten to the value
listed in Appendix B to ensure the valve gasket is
properly seated. NOTE: Gaskets and O-rings are not
normally reusable.
4. Replace the O-ring and valve cap and tighten to the
value listed in Appendix B. O-rings sealing the valve
caps should be replaced.
5. Check bolts and valve holddown screws after first
week of operation. Re-torque if necessary. See
Appendix B for torque values.
Valve Inspection and/or Replacement for Models
491, 691 and 891 Compressors
Before removing and inspecting the valves, begin by
depressurizing and purging (if necessary) the unit.
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