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14
• Model SH2-M
sh2mdl7sm-rev1218
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. Inspect
the surface of the check valve for surface imperfections. Replace as necessary.
DIAPHRAGM SERVICING/FILLING DRIVER FLUID
Motive power is delivered to the single diaphragm of the pump through a fluid cell located between the diaphragm and the drive piston. During preventative
maintenance servicing (where the diaphragm has not ruptured, and the fluid cell is still filled), the fluid should be drained from the chamber by removing
the pipe plug, in the lower most portion of inner chamber. To fill the fluid cell, the piston(s) must be on full discharge stroke. To do this and hold during fill
procedure, remove the fitting from the cylinder cap and insert air pressure. This need not be more than 10 PSI. The pressure will move the piston(s) and hold
them in the discharge position. Remove the pipe plug at the top of the fluid chamber, and fill the chamber with ethylene glycol (anti-freeze). The chamber
will take 3000 ml (101.5 fluid ounces) of fluid. If the diaphragm is Teflon, use 2800 ml (95 fluid ounces). Tilt the pump to evacuate air pockets from the fluid
chamber. A box wrench can be used to flex the diaphragm and purge air from the fluid chamber. Fill the chamber to the top of the fill hole, and re-insert the
pipe plug, using thread compound. If the glycol cell fluid is not compatible with the pumped product or would form a potentially dangerous mixture if the
diaphragm ruptured, consult the factory before choosing an alternative fluid.
CYLINDER PISTON SERVICING
The driver fluid must be drained (see above) to service the cylinder piston. The piston seals are different on the air side versus the driver fluid side. Typically,
the fluid side will require replacement before the air side. Remove the nuts and washers that secure the air side piston cap and inner fluid chamber to the
intermediate bracket. The cylinders may now be removed. Inspect the cylinder wall carefully. Scratches can cause driver fluid to leak to the air side of the
pump, which can find its way to the exhaust muffler. Scratches on the air cylinder will cause too much air to leak when on pressure stroke. The locknuts
holding the cylinder to the rod can now be removed. Carefully inspect the piston for scratches, burrs and wear, especially if the piston seals are worn. The
piston seals can now be inspected or replaced. AIR SIDE–The air side piston has a T-Seal. If the seal is worn showing flat areas or gouges, it will require
replacement. Remove seal and back-up (spacer). Remove wear rings and carefully inspect for wear. During reassembly make sure the ends of the backup
spacer and wear ring end are not across from each other. WET SIDE–The wet side piston has a yellow PSP seal. Inspect for flat spots and gouges. Behind
the seal is an energizer ring that helps to load the seal against the cylinder wall. (The energizer ring is included with the new seal.) The wear rings are the
same as on the air side. Again, make sure the ends are not across from each other. Reassembly of both pistons is the opposite of removal. Make sure the
side of the
locknut with the seal is next to the piston.
The groove in the piston or o-ring must be toward the pump center (o-ring seals next to the rod).
Apply a heavy oil, such as STP or 50W gear oil, to the piston seals when sliding on the cylinder. The piston/nut should be torqued at 500 in-lbs. (56.49
Newton meters). The studs that secure the cylinders to the intermediate should be torqued at 250 in-lbs. (28.24 Newton meters).
IMPORTANT NOTE:
Reassembly of the wet side piston/seal assembly differs from the air side in that it must be carefully pressed into the cylinder. An
arbor press is commonly used for this task.
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 opera-
tion. There may be instances of personal preference or poor quality air supplies when lubrication of the compressed air supply is required. The pump air
distribution system will operate with a properly lubricated compressed air supply. 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 (avail-
able from Warren Rupp) to supplement a plant’s air drying equipment. This device will remove excess water from the compressed air supply and reduce
the frequency of icing or freezing.
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 visit the Warren Rupp website. To receive the correct manual, you must specify the MODEL and TYPE
information found on the name plate of the pump.
Main Air Valve
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. 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. Reinstall 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, reinstall the valve body on the pump using new gaskets. Tighten the four hex head capscrews evenly and in an alternating cross pattern.
PILOT VALVE ACTUATOR SERVICING
The bushings for the pilot valve actuators are threaded into the intermediate bracket from the outside. The plunger may be removed for inspection or re-
placement 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 circum-
stances, it may become necessary to replace the o-ring seal. The bushing can be pushed through the inner chamber by removing the outer chamber the
assembly to reach the bushing.
UNIVERSAL ALL SP
5: WET END
