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 = 400 kPaPQ = 60 L/s

A pump raises the pressure of 60 L/s of water by 400 kPa. Inlet and outlet are at the same height and have the same diameter. Find the hydraulic power Ph in kW.

Q = 60 L/sΔp = 400 kPa
Ph = kW
2.Easy
PQ = 75 L/sH = 9 m

A pump delivers 75 L/s of water (ρ = 1000 kg/m³) against a total head of 9 m. Use g = 9.81 m/s². Find the hydraulic power Ph given to the water, in kW.

Q = 75 L/sH = 9 mρ = 1000 kg/m³g = 9.81 m/s²
Ph = kW
3.Medium
PQ = 150 L/sH = 68 m

A pump with an efficiency of 65% delivers 150 L/s of water (ρ = 1000 kg/m³) against a head of 68 m. Use g = 9.81 m/s². Find the shaft power Pshaft needed, in kW.

Q = 150 L/sH = 68 mη = 65%g = 9.81 m/s²
Pshaft = kW
4.Medium
PQ = 20 L/sH = 38 m

A pump delivers 20 L/s of water (ρ = 1000 kg/m³) against a head of 38 m. The pump efficiency is 65% 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 = 20 L/sH = 38 mηpump = 65%ηmotor = 95%g = 9.81 m/s²
Pel = kW
5.Hard
PQ = 50 L/sΔz = 13 mL = 500 m, D = 150 mm, f = 0.015, ΣK = 5

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 13 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 = 5 (entrance and exit included). Use g = 9.81 m/s². The pump efficiency is 72%. Find the shaft power Pshaft in kW.

Q = 50 L/sΔz = 13 mL = 500 mD = 150 mmf = 0.015ΣK = 5η = 72%
Pshaft = kW
6.Hard
PQ = 50 L/sΔz = 29 mL = 200 m, D = 150 mm, f = 0.02, 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 29 m higher. The pipe is 200 m long with an inside diameter of 150 mm and a Darcy friction factor f = 0.02; the minor-loss coefficients add up to ΣK = 6 (entrance and exit included). Use g = 9.81 m/s². The pump efficiency is 70%. Find the shaft power Pshaft in kW.

Q = 50 L/sΔz = 29 mL = 200 mD = 150 mmf = 0.02ΣK = 6η = 70%
Pshaft = kW

Answer key

  1. 1. Ph = 24 kW
  2. 2. Ph = 6.622 kW
  3. 3. Pshaft = 153.9 kW
  4. 4. Pel = 12.07 kW
  5. 5. Pshaft = 24.14 kW
  6. 6. Pshaft = 29.66 kW

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