SELF-PRIMING CENTRIFUGAL PUMPS
OM--04760
OPERATION
PAGE C -- 3
ter the pump cools, drain the liquid from
the pump by removing the casing drain
plug. Use caution when removing the
plug to prevent injury to personnel from
hot liquid.
If overheating does occur, stop the pump immedi-
ately and allow it to cool before servicing it.
Ap-
proach any overheated pump cautiously
.
As a safeguard against rupture or explosion due to
heat, some pumps are equipped with a pressure
relief valve which will open if vapor pressure within
the pump casing reaches a critical point. It is rec-
ommended that the pressure relief valve assembly
be replaced at each overhaul, or any time the
pump casing overheats and activates the valve.
Never
replace this valve with a substitute which
has not been specified or provided by the Gorman-
Rupp Company.
Strainer Check
If a suction strainer has been shipped with the
pump or installed by the user, check the strainer
regularly, and clean it as necessary. The strainer
should also be checked if pump flow rate begins to
drop. If a vacuum suction gauge has been in-
stalled, monitor and record the readings regularly
to detect strainer blockage.
Never
introduce air or steam pressure into the
pump casing or piping to remove a blockage. This
could result in personal injury or damage to the
equipment. If backflushing is absolutely neces-
sary, liquid pressure
must
be limited to 50% of the
maximum permissible operating pressure shown
on the pump performance curve.
If the pump is fit-
ted with a Gorman-Rupp double grease lubri-
cated seal, the maximum incoming pressure
must be reduced to 10 p.s.i.
Pump Vacuum Check
With the pump inoperative, install a vacuum gauge
in the system, using pipe dope on the threads.
Block the suction line and start the pump. At oper-
ating speed the pump should pull a vacuum of 20
inches (508 mm) or more of mercury. If it does not,
check for air leaks in the seal, gasket, or discharge
valve.
Open the suction line, and read the vacuum gauge
with the pump primed and at operation speed.
Shut off the pump. The vacuum gauge reading will
immediately drop proportionate to static suction
lift, and should then stabilize. If the vacuum reading
falls off rapidly after stabilization, an air leak exists.
Before checking for the source of the leak, check
the point of installation of the vacuum gauge.
Operational Checks
Check the pump for proper operation when it is first
started and periodically thereafter to identify minor
problems.
Check the pump for unusual noises or excessive
vibration while it is operating. If noise or vibration is
excessive, stop the pump and refer to
Trouble-
shooting
in the Maintenance And Repair Manual
for possible causes.
To avoid serious damage to the pump,
check for unusual noises or excessive vi-
bration while the pump is running. If noise
or vibration is excessive, stop operation
and refer to the troubleshooting chart in the
Maintenance and Repair manual.
STOPPING
Never halt the flow of liquid suddenly. If the liquid
being pumped is stopped abruptly, damaging
shock waves can be transmitted to the pump and
piping system. Close all connecting valves slowly.
On engine driven pumps, reduce the throttle
speed slowly and allow the engine to idle briefly be-
fore stopping.
If the application involves a high discharge
head, gradually close the discharge
throttling valve before stopping the pump.
