Design & SizingQuestion 25 of 110
A sewage ejector pump must handle a building with a discharge of 30 gpm against 18 ft of total head. Using WHP = (gpm x head in ft) / 3,960, what is the water horsepower?
a.0.14 hp
b.0.07 hp
c.0.10 hp
d.0.27 hp
Explanation
WHP = (30 x 18) / 3,960 = 540 / 3,960 = 0.136 hp, about 0.14 hp. The 3,960 constant is used when head is expressed in feet rather than psi. As with any pump, the motor is oversized above this by dividing by the pump efficiency.
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