dmf2dl5sm-rev0317
Model DMF2 Page 7
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, gasket and bumper 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. 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. Reinstall 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, reinstall the valve body
on the pump using new gaskets. Tighten the four hex head capscrews evenly
and in an alternating cross pattern.
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. (See page 7)
Freezing or icing-up of the air exhaust can occur under certain temperature
and humidity conditions. Use of an air 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.
FLAP VALVE SERVICING
Valve inspection requires removal of 3/8" hex nuts and elbows. When
the top suction elbows are removed, the valve and seat are connected as
an assembly. When the bottom discharge elbows are removed, the valve
and seat stay with the outer chamber. Visual inspection and cleaning is
possible. If parts are to be replaced, remove the self-locking nuts and all parts
are accessible.
