Water Source and Storage Calculations - Basic Mathematics for Water and Wastewater Operators - page 225

■ Example 15.10
Problem: The pumping water level for a well pump is 150 ft and the discharge pres-
sure measured at the pump discharge centerline is 3.5 psi. If the flow rate from the
pump is 700 gpm, use Equation 15.11 to calculate the water horsepower.

Solution: First calculate the field head. The discharge head must be converted from
psi to ft:

3.5 psi × 2.31 ft/psi = 8.1 ft

The field head, therefore, is

150 ft + 8.1 ft = 158.1 ft

The water horsepower can now be determined:

Fieldhead (ft)Capacity (gpm)
33,0

×
00 ft-lb/min

Water hp =

158.1 ft × ×

3,000 ft-lb/min

700 gpm 8.34 lb/gal

= = 28 whp

3

■ Example 15.11
Problem: The pumping water level for a pump is 170 ft. The discharge pressure mea-
sured at the pump discharge head is 4.2 psi. If the pump flow rate is 800 gpm, use
Equation 5.11 to calculate the water horsepower.

Solution : The field head must first be determined. To determine field head, the dis-
charge head must be converted from psi to ft:

4.2 psi × 2.31 ft/psi = 9.7 ft

The field head can now be calculated:

170 ft + 9.7 ft = 179.7 ft

And the water horsepower can be calculated:

179.7 ft 800 gpm
3960

×

Water hp = = 36 whp

■ Example 15.12
Problem: A deep-well vertical turbine pump delivers 600 gpm. The lab head is 185
ft and the bowl efficiency is 84%. What is the bowl horsepower?