SANDPIPER PB1-A - Manual (Page 4)

PB1-A Type 3 Page 4 520-032-000 5/99
care that the bumper stays in place allowing the sleeve to press in all the way. Re-
install the spool, opposite end cap, gasket and bumper on the valve body. After
inspecting and cleaning the gasket surfaces on the valve body and intermediate, re-
install the valve body on the pump using new gaskets. Tighten the four hex head
capscrews evenly and in an alternating cross pattern.
Models with 1" suction/discharge or larger, and NON-METAL center sections:
The main air valve sleeve and spool set is located in the valve body mounted on
the pump with four hex head capscrews. He valve body assembly is removed from
the pump by removing these four hex head capscrews.
With the valve body assembly off the pump, access to the sleeve and spool set
is made by removing a retaining ring (each end) securing the end cap on the valve
body assembly. With the end caps removed, slide the spool back and forth in the
sleeve. The spool is closely sized to the sleeve and must move freely to allow for
proper pump operation. An accumulation of oil, dirt or other contaminants from the
pump’s air supply, or from a failed diaphragm, may prevent the spool from moving
freely. This can cause the spool to stick in a position that prevents the pump from
operating. If this is the case, the sleeve and spool set should be removed from the
valve body for cleaning and further inspection.
Remove the spool from the sleeve. Using an arbor press or bench vise (with an
improvised mandrel), press the sleeve from the valve body. Take care not to damage
the sleeve. At this point, inspect the o-rings on the sleeve for nicks, tears or abrasions.
Damage of this sort could happen during assembly or servicing. A sheared or cut o-
ring can allow the pump’s compressed air supply to leak or bypass within the air valve
assembly, causing the pump to leak compressed air from the pump air exhaust or not
cycle properly. This is most noticeable at pump dead head or high discharge pressure
conditions. Replace any of these o-rings as required or set up a routine, preventive
maintenance schedule to do so on a regular basis. This practice should include
cleaning the spool and sleeve components with a safety solvent or equivalent,
inspecting for signs of wear or damage, and replacing worn components.
To re-install the sleeve and spool set, lightly lubricate the o-rings on the sleeve with
an o-ring assembly lubricant or lightweight oil such as 10 wt. air line lubricant). Re-
install one end cap, and retaining ring on the valve body. Using the arbor press or
bench vise that was used in disassembly, carefully press the sleeve back into the valve
body, without shearing the o-rings. Re-install the spool, opposite end cap and
retaining ring on the valve body. After inspecting and cleaning the gasket surfaces on
the valve body and intermediate, reinstall the valve body on the pump using new
gaskets. Tighten the four hex head capscrews evenly and in an alternating cross
pattern, at 150 in./lbs. (16.94 Newton meters).
PILOT VALVE SERVICING
This assembly is reached by removing the air distribution valve body from the
pump and lifting the pilot valve body out of the intermediate housing (see Fig. 7).
When reinserting an externally serviceable pilot valve, push both plungers out of
the path of the pilot valve so that they and the pilot valve are not damaged.
Service Note: If a problem arises with the pilot valve, it is usually corrected by
replacing only o-rings. Always grease the spool prior to inserting into the sleeve. If the
sleeve is removed from the body, reinsertion must be from the same side it was
removed from, the chamfered side. Again, grease the o-rings so that it slides into the
body. Make sure the retaining ring has securely been inserted around the sleeve.
PILOT VALVE ACTUATOR SERVICING
The bushings for the pilot valve actuators are pressed into the inner chambers from
the outside (see Fig. 8). The plunger may be removed for inspection or replacement
from the inside by removing the air distribution valve body and the pilot valve body from
the pump. The plungers should be visible as you look into the intermediate from the
top. Depending on their position, you may find it necessary to use a fine piece of wire
to pull them out.
Under rare circumstances, it may become necessary to replace the o-ring seal.
The bushing can be pushed through the inner chamber by removing the outer
chamber assembly to reach the bushing and removing the bushing retaining ring.
CAUTION
In the event of diaphragm rupture,
pumped material may enter the air end
of the pump, and be discharged into the
atmosphere. If pumping a product which
is hazardous or toxic, the air exhaust
must be piped to an appropriate area for
safe disposition.
CAUTION
Before maintenance or repair, shut off
the compressed air line, bleed the pres-
sure, and disconnect the air line from
the pump. The discharge line may be
pressurized and must be bled of its
pressure. When used for toxic or ag-
gressive fluids, the pump should
always be flushed clean prior to
disassembly.
IMPORTANT
Before pump operation, all external
gasketed fasteners must be inspected
for looseness caused by gasket creep
after leaving the factory. Retorque loose
fasteners to insure against leakage.
Follow recommended torques where
called out. (A card is attached to each
new pump stating this fact.)
This pump is pressurized internally with
air pressure during operation. Always
make certain that all bolting is in good
condition and that all of the correct
bolting is reinstalled during assembly.