Pumps & pump power worksheet with answers

Free printable Pumps & pump power worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
Δp = 450 kPaPQ = 10 L/s

A pump raises the pressure of 10 L/s of water by 450 kPa. Inlet and outlet are at the same height and have the same diameter. Find the hydraulic power Ph in kW.

Q = 10 L/sΔp = 450 kPa
Ph = kW
2.Easy
PQ = 20 L/sH = 5 m

A pump delivers 20 L/s of water (ρ = 1000 kg/m³) against a total head of 5 m. Use g = 9.81 m/s². Find the hydraulic power Ph given to the water, in kW.

Q = 20 L/sH = 5 mρ = 1000 kg/m³g = 9.81 m/s²
Ph = kW
3.Medium
PQ = 50 L/sH = 28 m

A pump delivers 50 L/s of water (ρ = 1000 kg/m³) against a head of 28 m. The pump efficiency is 72% and the electric motor driving it has an efficiency of 95%. Use g = 9.81 m/s². Find the electrical power Pel the motor draws, in kW.

Q = 50 L/sH = 28 mηpump = 72%ηmotor = 95%g = 9.81 m/s²
Pel = kW
4.Medium
PQ = 25 L/sH = 60 m

A pump with an efficiency of 82% delivers 25 L/s of water (ρ = 1000 kg/m³) against a head of 60 m. Use g = 9.81 m/s². Find the shaft power Pshaft needed, in kW.

Q = 25 L/sH = 60 mη = 82%g = 9.81 m/s²
Pshaft = kW
5.Hard
PQ = 12 L/sΔz = 10 mL = 300 m, D = 100 mm, f = 0.022, ΣK = 8

A pump moves 12 L/s of water (ρ = 1000 kg/m³) from an open lower reservoir to an upper tank whose water surface is 10 m higher. The pipe is 300 m long with an inside diameter of 100 mm and a Darcy friction factor f = 0.022; the minor-loss coefficients add up to ΣK = 8 (entrance and exit included). Use g = 9.81 m/s². The pump efficiency is 80%. Find the shaft power Pshaft in kW.

Q = 12 L/sΔz = 10 mL = 300 mD = 100 mmf = 0.022ΣK = 8η = 80%
Pshaft = kW
6.Hard
PQ = 50 L/sΔz = 25 mL = 500 m, D = 150 mm, f = 0.015, ΣK = 6

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 25 m higher. The pipe is 500 m long with an inside diameter of 150 mm and a Darcy friction factor f = 0.015; the minor-loss coefficients add up to ΣK = 6 (entrance and exit included). Use g = 9.81 m/s². The pump efficiency is 65%. Find the shaft power Pshaft in kW.

Q = 50 L/sΔz = 25 mL = 500 mD = 150 mmf = 0.015ΣK = 6η = 65%
Pshaft = kW

Answer key

  1. 1. Ph = 4.5 kW
  2. 2. Ph = 0.981 kW
  3. 3. Pel = 20.08 kW
  4. 4. Pshaft = 17.95 kW
  5. 5. Pshaft = 2.767 kW
  6. 6. Pshaft = 36.11 kW

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