4
discharge pipe to allow for minimum liquid flow through the
pump. Minimum liquid flow through the pump is needed for
cooling and lubrication of the pump (see Specifications). Run the
bypass/relief valve and discharge pipe to a floor drain or a tank
for collection.
Suction pipe should be adequately sized (see Specifications) and
run as straight and as short as possible to keep friction losses to a
minimum. Pipes, valves, and fittings must have a pressure rating
equal to or greater than the maximum system pressure.
Pressure check the discharge piping as required by codes or local
regulations.
“Inlet” and “Outlet” are marked on the pump base to show the
direction of the liquid flow through the pump.
Install antivibration mountings on either side of the pump if a
minimum noise level is desired.
Install isolation valves in both inlet and outlet pipes near the
pump (see Figure 3). This allows for removal of pump for service
without draining the system and isolation of the pump in case of
a flooded suction condition.
Install a check valve in the discharge pipe to prevent high system
pressure from backing up to the inlet side of the pump. Excessive
inlet pressure can cause the pump to exceed its maximum
permissible operating pressure.
Make sure, especially on the inlet side of the pump, that there are
no airlocks in the system. See Figure 4 for correct pipe work to
avoid airlocks. The suction pipe should be level or slightly rising.
Support all piping independently of the pump so the weight of the
piping system does not strain the pump case. Make sure that the
expansion and contraction of the piping system from temperature
variations cannot put a strain on the pump.
If the system or pump must be drained periodically (especially if
the discharge pipe is horizontal or slopes downward away from
the pump), install a loop and vacuum valve as shown in Figure 5
to protect the pump against running dry. The highest point of the
loop should be at least as high as the lowest point of the motor.
This loop/valve combination will allow the pump and the system
to be drained independently of one another.
Inlet
Outlet
Nipple
Orifice
Bypass Line
12" Min.
to prevent
erosion
Isolation Valves
Figure 3. Bypass required if pump might operate with discharge
valve closed. See PVM32 Specifications for minimum required flow
through pump to prevent overheating and to ensure lubrication.
O.K.
O.K.
Figure 4. Install pipe correctly to prevent air locks.
Vacuum Valve
Figure 5. Loop and vacuum valve installation.