Plotting Points based on Discharge Pressure
Gauge Readings - A pressure gauge is located
at the discharge of the pump. A
throttling valve is just after the gauge, in
the discharge pipe. A flow meter is just after
the valve, measuring flow in the discharge
pipe. The points shown on the curve are
determined by running the pump at full
speed. Reading the curve points from left to
right, point number 1 shows the
discharge pressure when the valve is CLOSED.
There is no flow. Point number 2 is determined
by opening the valve until 5 gallons per minute
(GPM) of flow occurs and pressure on the
discharge gauge is recorded. The sequence is
continued for each remaining point. NOTE:
Running the pump at full speed with the
discharge valve completely closed is known as a
dead-head condition for the pump and can damage
the pump.