SANDPIPER ST40 - Manual (Page 11)

st15dl4sm-rev0614 Models ST1½, ST40 Page 9
(44.74 Newton meters) alternating from one side to the other in the process. Do not
overtighten these bolts due to the nature of PTFE to cold flow.
Reinstall the pumping chamber assembly on the pump as it was removed and fill with
the driver liquid as called out in this text. After complete re-assembly the unit should be
tested prior to installation on the job simply to make sure the capscrews and hex nuts
are torqued down properly to ensure no leakage around the PTFE diaphragm surfaces.
A NOTE ABOUT AIR VALVE LUBRICATION
The SANDPIPER pump’s pilot valve and main air valve assemblies are designed
to operate WITHOUT lubrication. This is the preferred mode of operation. There may
be instances of personal preference, or poor quality air supplies when lubrication of
the compressed air supply is required. The pump air system will operate with properly
lubricated compressed air supplies. Proper lubrication of the compressed air supply
would entail the use of an air line lubricator (available from Warren Rupp) set to deliver
one drop of 10 wt., non-detergent oil for every 20 SCFM of air the pump consumed at its
point of operation. Consult the pump’s published Performance Curve to determine this.
It is important to remember to inspect the sleeve and spool set routinely. It should
move back and forth freely. This is most important when the air supply is lubricated. If a
lubricator is used, oil accumulation will, over time, collect any debris from the compressed
air. This can prevent the pump from operating properly.
Water in the compressed air supply can create problems such as icing or freezing
of the exhaust air causing the pump to cycle erratically, or stop operating. This can be
addressed by using a point of use air dryer to supplement a plant’s air drying equipment.
This device will remove excess water from the compressed air supply and alleviate the
icing or freezing problem.
ESADS: EXTERNALLY SERVICEABLE AIR
DISTRIBUTION SYSTEM
Please refer to the exploded view drawing and parts list in the Service Manual supplied
with your pump. If you need replacement or additional copies, contact your local Warren
Rupp Distributor, or the Warren Rupp factory Literature Department at the number shown
below. To receive the correct manual, you must specify the MODEL and TYPE in formation
found on the name plate of the pump.
MODELS WITH 1" SUCTION/DISCHARGE OR LARGER, AND
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. The 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 four hex head capscrews (each end) on the end caps of 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.