A pump operating at a given speed n11480 rpm delivers a give

A pump operating at a given speed n1=1480 rpm delivers a give flow Ql= 210 gpm at a given head 1-11=83 ft. If the pump operates at a different speed n2=1600 gpm, what are the corresponding head (H2) and discharge (Q2)? Given pump speed n=2200 rpm, flow rate Q=0.03 m3/s, and head H=30 m, calculate the type number (ns), flow in L/min, and efficiency (e) and then recommend a pump type. Use the following figure.

Solution

Solution1.

By pump affinity laws,

Q1 / Q2 = N1 / N2

210 / Q2 = 1480 / 1600

Q2 = 227.027 gpm

Again, by pump affinity laws

H1 / H2 = (N1 / N2)²

83 / H2 = (1480 / 1600)²

H2 = 97.005 ft