Pumps & pump power worksheet with answers

A pump raises the pressure of 50 L/s of water by 750 kPa. Inlet and outlet are at the same height and have the same diameter. Find the hydraulic power P_h in kW.

A pump delivers 25 L/s of water (ρ = 1000 kg/m³) against a total head of 21 m. Use g = 9.81 m/s². Find the hydraulic power P_h given to the water, in kW.

In a test, a pump delivers 100 L/s of water (ρ = 1000 kg/m³) against a head of 40 m while its shaft takes 56.1 kW. Use g = 9.81 m/s². Find the pump efficiency η in percent.

A pump delivers 10 L/s of water (ρ = 1000 kg/m³) against a head of 36 m. The pump efficiency is 70% and the electric motor driving it has an efficiency of 94%. Use g = 9.81 m/s². Find the electrical power P_el the motor draws, in kW.

A pump moves 50 L/s of water (ρ = 1000 kg/m³) from an open lower reservoir to an upper tank whose water surface is 39 m higher. The pipe is 200 m long with an inside diameter of 150 mm and a Darcy friction factor f = 0.018; the minor-loss coefficients add up to ΣK = 8 (entrance and exit included). Use g = 9.81 m/s². The upper tank is closed and the air above its water is at a gauge pressure of 300 kPa. Find the head H the pump must add.

A pump moves 80 L/s of water (ρ = 1000 kg/m³) from an open lower reservoir to an upper tank whose water surface is 36 m higher. The pipe is 150 m long with an inside diameter of 200 mm and a Darcy friction factor f = 0.018; the minor-loss coefficients add up to ΣK = 8 (entrance and exit included). Use g = 9.81 m/s². The upper tank is closed and the air above its water is at a gauge pressure of 400 kPa. Find the head H the pump must add.