SANDPIPER MP07D - Manual (Page 3)

520-134-000 3/03 Model MP07D Design Level 3 Page 3
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). Press
the set into the valve body easily, without shearing the o-rings. Re-install one end cap,
gasket and bumper on the valve body. Using the arbor press or bench vise that was
used in disassembly, press the sleeve back into the valve body. You may have to clean
the surfaces of the valve body where the end caps mount. Material may remain from
the old gasket. Old material not cleaned from this area may cause air leakage after
reassembly. Take care that the bumper stays in place allowing the sleeve to press in
all the way. Re-install the spool, the 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.
OPERATION
Your Marathon pump has been tested prior to shipment and is ready for use as
received. It is completely self-priming and no initial filling with fluid is required.
If the unit is to be totally submerged, the air exhaust must be piped above the
liquid level to prevent the liquid and foreign material from entering the air
distribution valve mechanism.
Open the inlet air valve at least one turn to allow sufficient cycling rate for the
pump to prime (30 to 60 cycles per minute). After pumping starts, adjust the inlet air
valve for the desired pumping capacity. When further opening of the inlet air valve
increases cycling rate without increasing the flow rate, the pump is being starved of
liquid due to suction limitations. Further opening of the air inlet valve will waste
compressed air. Set the inlet air valve for lowest cycling rate that does not decrease
flow rate for most efficient operation.
FREEZING OR ICING OF EXHAUST
Icing of the air exhaust can occur under certain conditions of temperature and
humidity on compressed air power equipment. When pump performance suffers
because of icing, use of an air dryer will solve the problem. Icing is more likely to
occur at high discharge pressures.
AIR EXHAUST
Marathon pumps can be submerged if the materials of construction are
compatible with the liquid and the exhaust is piped above the liquid level. (See
OPERATION, above.) Piping used for the exhaust should not be smaller than 1"
pipe size. Reduced pipe size can restrict the exhausted air and reduce pump
performance.
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.
DIAPHRAGM SERVICING:
Driver Diaphragms
Drain the driver diaphragm chamber by removing the boss plug on the
underside of the driver chamber. Remove eight bolts securing the two manifolds to
the chambers. Remove eight bolts securing the diaphragm chamber. This permits
inspection of the Teflon diaphragm and the driver diaphragm. Loosen the plate
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
Do not use a wrench on the
diaphragm rod. Flaws on the surface
may damage the bearings and seals.