The following data were recorded when a centrifugal pump worked at its maximum efficiency: Q = 40 lps; Manometric head developed = 25 m; Input shaft horse power = 11.9 W. What is the non-dimensional specific speed of the pump if it was running at 1500 rpm? (May adopt the following (all in S.I. units):
G1/4 = 1.77, g1/2 = 3.132, g3/4 = 5.544,
√2 = 1.414 √5 = 2.236 and √10 = 3.162)1
165
2
155
3
145
4
135