SANDPIPER HDF4-A - Manual (Page 9)

hdf3adl7sm-rev0614 Model HDF3-A & HDF4-A Page 7
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.
AIR EXHAUST
If a diaphragm fails, the pumped liquid or fumes can enter the air end of the pump, and
be exhausted into the atmosphere. When pumping hazardous or toxic materials, pipe the
exhaust to an appropriate area for safe disposition.
This pump can be submerged if materials of construction are compatible with the liquid.
The air exhaust must be piped above the liquid level. Piping used for the air exhaust must
not be smaller than 1" (2.54 cm). Reducing the pipe size will restrict air flow and reduce
pump performance. When the product source is at a higher level than the pump (flooded
suction), pipe the exhaust higher than the product source to prevent siphoning spills.
Freezing or icing-up of the air exhaust can occur under certain temperature and
humidity conditions. Use of a Warren Rupp Extractor/Dryer unit should eliminate most
icing problems.
BETWEEN USES
When used for materials that tend to settle out or transform to solid form, the pump
should be completely flushed after each use, to prevent damage. Product remaining
in the pump between uses could dry out or settle out. This could cause problems with
valves and diaphragms at re-start. In freezing temperatures, the pump must be drained
between uses in all cases.
CHECK VALVE SERVICING
For flap valve inspection or replacement, remove the flange bolts securing the suction
and discharge elbows and loosen Dresser-type couplings. The flap valves are exposed
for inspection or servicing upon removal of elbows.
DIAPHRAGM SERVICING
Diaphragms are serviced by removing the outer diaphragm chambers which are
secured with 12 bolts. After removing the outer chamber, unbolt the diaphragm plate by
removing 6 socket head capscrews (Allen wrench required). To remove the diaphragm
rod, remove the inner diaphragm plate secured by a nut on the end of the diaphragm rod.
The opposite diaphragm and rod can then be removed as a unit. The interior components
consisting of sleeve bearings, rod seals, and pilot valve actuator bushings are now
accessible for service if required.
REASSEMBLY
All procedures for reassembling the pump are the reverse of the above with these
further instructions:
1. Install the diaphragms with their natural bulge outward. Make certain that the rubber
diaphragm rod bumper is installed on the rod behind each inner diaphragm plate. Re-
torque the 6 socket head capscrews that secure the diaphragm between the plates to 30
foot Ibs. (40.67 Newton meters) torque reading.
2. Caution should be used while reassembling the check valves. The valves are
designed for some preload over the retainer and the 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 primes. However, after priming action has started,
valves will function due to differential pressure without concern or trouble.