Question

A water pump delivers 6 hp of shaft power when operating. The pressure differential between the outlet and the inlet of the pump is measured to be 1.2 psi when the flow rate is 10 ft³/s, and the velocity changes to 5 ft/s from 2 ft/s as the water passes through the pump. Determine the mechanical efficiency of this pump assuming the water density to be 62.4 lbm/ft³ (written in decimal form with 3 significant figures).  

Answer 1

Calculate the theoretical pump head using Bernoulli equation for the flow. P: V?th - Po V2 Pg2g Pg 2g h, Po-Pi/V.?-v? Pg2g _(1.2x(12)'), (5)2-(2) = h, 3.095 ft (62.4) 2(32.2) Calculate the theoretical pumping power delivered. Price = PgQh, =YQh, = (62.4)(10)(3.095 )= 1931.28 1b-ft/sec ==> 1931.28 - hp = 3.511 hp Calculate the mechanical efficiency of this pump. n. Preoretical = (3.311) = 0.5852 358.5%