Water-Lifting Devices – Pumps - Practices of Irrigation and On-farm Water Management - page 466

• Align the motor coupling with the motor shaft, while lowering the pump end onto

the motor.

• Replace all capscrews and lockwashers furnished with the pump and bolt up

tightly.

12.9.2 Pump Operation

12.9.2.1 Suction Line

The suction line should be designed so pump inlet pressure, measured at pump inlet
flange, is greater than or equal to the minimum required pump inlet pressure (also
referred to as Net Positive Inlet Pressure Required or NPIPR). Suction line length
should be as short as possible with piping diameters being equal to or larger than
pump's inlet size. All joints in suction line must be leak free.

12.9.2.2 Field Test

When a field test of the pump's performance is required, the following reading
should be taken:

• Discharge rate measurement

• Total head and horsepower measurement

• Rotating speed

• Liquid temperature

Compare the results of the field test with the performance curve for your pump.

Capacity (Discharge Rate) Measurement

Measure the rate of flow (volume per unit time) from the pump discharge, prefer-
ably in liter per second (l/s) or m 3 /s. The volume and/or flow rate measurement
may be done using any of the following equipment: accurately measured reservoir,
calibrated venturi meter, orifice meter, flume, etc.

Total Head Measurement

The total pumping head consists of distance from the water level in the sump (when
pumping) to the center of the discharge pressure gauge, plus the discharge gauge
reading, and the velocity at the discharge. Convert gauge reading using the relation
P

= ω h , where ω is the density of water.

Horse Power Requirement

Measure the horsepower consumption of the pump by a direct reading of a wattmeter
and applying the reading to the following formula:

BHP = (kW Input × Efficiency) / 0.746