SANDPIPER PB1/2-A - Manual (Page 3)

520-041-000 2/99 Model PB½ -A Type 3 Page 3
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 available from Warren Rupp) to supple-
ment 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 information found on the name plate of the pump.
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 assembIy 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 spooI 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 his 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 suppiy to leak or bypass within the air valve
assembly, causing the pump to leak compressed alr from the pump air exhaust or not
cycle properly. This is most noticeable at pump dead head or high discharge pres-
sure conditions. Replace any of these o-rings as required or set up a routine, preven-
tive maintenance schedule to do so on a regular basls. This practice should include
cleaning the spool and sleeve components with a safety solvent or equivalent, in-
specting for signs of wear or damage, and replacing worn components.
To re-install the sleeve and spool set, Iightly lubricate the o-rings on the sleeve
with an o-ring assembly lubricant or lightweignt 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, and retaining ring on the valve body. Using the arbor press or bench vise
that was used in disassembly, press the sleeve back into the valve body. Re-install
the spool, keeping the counter-bored end toward you, and install the spring, opposite
end cap and retaining ring 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, at 70 in./lbs. (7.9 Newton meters).
CAUTION
Before maintenance or repair, shut off
the compressed air line, bleed the
pressure, 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
aggressive fluids, the pump should
always be flushed clean prior to
disassembly.
Figure 5: Sleeve and spool set.
Figure 6: Disassembling the pilot valve.
Figure 7: Pilot valve with o-rings.