Goulds Pumps 3409 - IOM - Manual (Page 23)

3409 IOM 11/04
23
DISCHARGE PIPING
If the discharge piping is short, the pipe diameter can be the
same as the discharge opening. If the piping is long, the
pipe diameter should be one or two sizes larger than the
discharge opening. On long horizontal runs, it is desirable
to maintain as even a grade as possible. Avoid high spots,
such as loops, which will collect air and throttle the system
or lead to erratic pumping.
A check valve and an isolating gate valve should be
installed in the discharge line. The check valve, placed
between pump and gate valve, protects the pump from
excessive back pressure, and prevents liquid from running
back through the pump in case of power failure. The gate
valve is used in priming and starting, and when shutting the
pump down.
PRESSURE GAUGES
Properly sized pressure gauges should be installed in both
the suction and discharge nozzles in the gauge taps
provided. The gauges will enable the operator to easily
observe the operation of the pump, and also determine if
the pump is operating in conformance with the
performance curve. If cavitation, vapor binding, or other
unstable operation should occur, widely fluctuating
discharge pressure will be noted.
Fig. 12
3