SANDPIPER ET1 1/2 - M - Manual (Page 7)

Model ET1 1 /
2
-M Type 3 Page 6 et15mdl3sm-rev0614
CHECK VALVE SERVICING
Need for inspection or service is usually indicated by poor priming, unstable cycling,
reduced performance or the pump’s cycling but not pumping.
Remove the six flange bolts securing the inlet and outlet flanges to the manifold.
Inspect the surfaces of both check valve and seat for wear or damage that could
prevent proper sealing. If pump is to prime properly, valves must seat air tight (see Fig. 6).
DIAPHRAGM SERVICING
Driver Diaphragms:
Drain the driver diaphragm chamber by removing the boss plug on the underside of
the driver chamber. NOTE: This is also the part used for leak detector probes. Remove
twelve bolts securing the two manifolds to the chambers. Remove eight bolts securing
the diaphragm chamber. This permits inspection of the TFE diaphragm and the driver
diaphragm. Loosen the plate which secures the diaphragm and plate to the rod by
keeping the diaphragm engaged with the inner diaphragm chamber. Insert two or three
capscrews through the bolt holes so the diaphragm cannot rotate when loosening. The
diaphragm plates, diaphragm and bumper will now come off the assembly. Repeat all
actions if the other diaphragm needs to be inspected or replaced.
NOTE: See “Filling of Driver Chamber with Liquid” for the correct procedure to
recharge the pump for operation.
Reassembly is the reverse of the tear down. During reassembly, be sure the rubber
bumper is on the rod on each side. Install the diaphragm with the natural bulge to the
outside as marked on the diaphragm. Be sure that the large radius side of each plate
is toward the diaphragm. Place the sealing washer between the inner diaphragm plate
and the end of the rod. Tighten the plate to approximately 25 ft. lbs. (3.456 pounds/sq.
cm.). Torque while allowing the diaphragm to turn freely with the plate. Hold the opposite
side with a wrench on the plate to prevent rotation of the rod. If the opposite chamber
is assembled, this will not be necessary.
When reassembling the outer chambers and the manifold, the bolts securing the
manifold flange to the chamber should be snugged prior to tightening the manifold
flange. Finish tightening the manifold flange bolts after the chamber bolting is secured.
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
(see Fig. 9).
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 held in the inner chambers with
retaining rings. An o-ring is behind each bushing. If the plunger has any sideways motion
check o-rings and bushings for deterioration or wear. 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 (see Fig. 10 and Fig. 11).