SANDPIPER DMF3S - Manual (Page 8)

dmf3sdl7sm-rev0614 Model DFM3S Page 6
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.