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8
• Model SH2-M
sh2mdl7sm-rev1218
Principle of Pump Operation
PRINCIPLE OF OPERATION
This pump is a 2:1 pressure ratio single acting pump powered by compressed air. The 2:1 ratio is achieved by simultaneously applying
air pressure over a single end of each of two pistons connected in series by a shaft. The two pressurized ends are those most distant
from the pumped fluid, with the force from the air pressure exerted in the direction of the pumped fluid. The combined force is transferred
through to the single end of the piston nearer to the pumped fluid—the single piston end having an area equal to one-half that of the two
“air” ends—and then through a fluid cell to a single pumping diaphragm.
On this single acting pump the suction stroke is independent of all discharge conditions and requires less air pressure than the discharge
stroke. The suction stroke is accomplished through an air regulator which pressurizes the piston area in the rear cylinder adjacent to the
intermediate bracket, while simultaneously exhausting the other two piston areas: one in the front cylinder, adjacent to the intermediate
bracket, and the other behind the rear cylinder piston, adjacent to the cap end.
OPERATION
The regulator is factory preset to 30 psi. After the pump is installed and in operation, the operator should raise or lower the setting until
maximum performance is determined by trial and error. A setting which is too high will result in excessively rapid and noisy operation,
with a loss in performance and eventually shortened pump life. The hose assemblies deliver air to the non-wetted portions of the pump,
and care should be taken that they are neither crimped nor cut.
INSTALLATION PROCEDURES
Position the pump as close as possible to the source of the liquid to be pumped. Avoid long or undersize suction lines and use the
minimum number of fittings. For permanent installation involving rigid piping, install short flexible sections of hose between the pump
and piping. This reduces strains and permits easier removal of the pump for service when required.
AIR SUPPLY
Do not connect the unit to an air supply in excess of 125 PSI (8.61 bars). Install a shutoff valve in the air supply line to permit removal of
the unit for servicing. When connecting an air supply of rigid piping, mount a section of flexible line to the pump to eliminate piping strain.
In permanent installations, an air-line filter is recommended.
FREEZING OR ICING OF EXHAUST
Icing of the air exhaust can occur under certain conditions of temperature and humidity on compressed air power equipment. Icing is
more likely to occur at high discharge pressures. Use of the Warren Rupp Air Dryer should eliminate the problem.
MAINTENANCE AFTER USE
When the pump is used for materials that tend to settle out or transform from liquid to solid form, care must be taken after each use or
during idle time to remove them and flush the pump as required to prevent damage. In freezing temperatures the pump must be completely
drained when idle. This model must be tilted to allow the liquid from the chambers to run out of the discharge port.
CAUTION
The air exhaust should
be piped to an area
for safe disposition
of the product being
pumped, in the event of
a diaphragm failure.
UNIVERSAL ALL AODD
2: INST
AL
& OP
