Blagdon Pump X50 Metallic Flap Valve - Manual (Page 10)

x50fvmdl6sm-rev0612 Page 8
gradually and evenly on both sides.
Caution should be used while reassembling Flap valves. The valves are designed for some preload over the retainer hinge pad.
This is done to insure proper face contact with the seat. After all parts are in place, tighten the lock nuts down on the assembly
to the point where visual inspection shows that seat and valve face mate without gap. This is important for dry prime. However,
after priming action has started, valves will function due to differential pressure without concern or trouble.
PILOT VALVE
The pilot valve assembly is accessed by removing the main air distribution valve body from the pump and lifting the pilot valve
body out of the intermediate housing.
Most problems with the pilot valve can be corrected by replacing the o-rings. Always grease the spool prior to inserting it
into the sleeve. If the sleeve is removed from the body, reinsertion must be at the chamfered side. Grease the o-rings to slide
the sleeve into the valve body. Securely insert the retaining ring around the sleeve. When reinserting the pilot valve, push both
plungers (located inside the intermediate bracket) out of the path of the pilot valve spool ends to avoid damage.
PILOT VALVE ACTUATOR
Bushings for the pilot valve actuators are threaded into the intermediate bracket from the outside. The plunger may be removed for
inspection or replacement. First remove the air distribution valve body and the pilot valve body from the pump. The plungers can be located
by looking into the intermediate. It may be necessary to use a fine piece of wire to pull them out. The bushing can be turned out through the
inner chamber by removing the outer chamber assembly. Replace the bushings if pins have bent.