VGH SERIES
OM-06114
OPERATION
PAGE C - 3
OPERATION
Pump speed and operating points must be
within the continuous performance range
shown on the pump curve (see page E-1).
Leakage
No leakage should be visible at pump mating sur
faces, or at pump connections or fittings. Keep all
line connections and fittings tight to maintain maxi
mum pump efficiency.
Liquid Temperature And Overheating
Refer to the Specification Data sheet for the
maxi
mum
liquid temperature for your specific pump.
Do not apply the pump at a higher operating tem
perature.
Overheating can occur if operated with the valves
in the suction or discharge lines closed. Operating
against closed valves could bring the liquid to a
boil, build pressure, and cause the pump to rup
ture or explode. If overheating occurs, stop the
pump and allow it to cool before servicing it. Refill
the pump casing with cool liquid.
Allow an over‐heated pump to com
pletely cool before servicing
.
Do not re
move plates, covers, gauges, or fittings
from an over‐heated pump. Liquid with
in the pump can reach boiling tempera
tures, and vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Af
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
.
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.
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
, Section D, for possible causes.
