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 = 300 kPaPQ = 10 L/s

A pump raises the pressure of 10 L/s of water by 300 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 = 300 kPa
Ph = kW
2.Easy
PQ = 12 L/sH = 14 m

A pump delivers 12 L/s of water (ρ = 1000 kg/m³) against a total head of 14 m. Use g = 9.81 m/s². Find the hydraulic power Ph given to the water, in kW.

Q = 12 L/sH = 14 mρ = 1000 kg/m³g = 9.81 m/s²
Ph = kW
3.Medium
PQ = 30 L/sH = 50 m

A pump with an efficiency of 82% delivers 30 L/s of water (ρ = 1000 kg/m³) against a head of 50 m. Use g = 9.81 m/s². Find the shaft power Pshaft needed, in kW.

Q = 30 L/sH = 50 mη = 82%g = 9.81 m/s²
Pshaft = kW
4.Medium
PQ = 80 L/sH = 60 m

A pump delivers 80 L/s of water (ρ = 1000 kg/m³) against a head of 60 m. The pump efficiency is 82% and the electric motor driving it has an efficiency of 94%. Use g = 9.81 m/s². Find the electrical power Pel the motor draws, in kW.

Q = 80 L/sH = 60 mηpump = 82%ηmotor = 94%g = 9.81 m/s²
Pel = kW
5.Hard
150 kPa (gauge)PQ = 120 L/sΔz = 12 mL = 300 m, D = 250 mm, f = 0.018, ΣK = 6

A pump moves 120 L/s of water (ρ = 1000 kg/m³) from an open lower reservoir to an upper tank whose water surface is 12 m higher. The pipe is 300 m long with an inside diameter of 250 mm and a Darcy friction factor f = 0.018; the minor-loss coefficients add up to ΣK = 6 (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 150 kPa. Find the head H the pump must add.

Q = 120 L/sΔz = 12 mL = 300 mD = 250 mmf = 0.018ΣK = 6ptank = 150 kPa
H = m
6.Hard
PQ = 40 L/sΔz = 25 mL = 100 m, D = 150 mm, f = 0.018, ΣK = 8

A pump moves 40 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 100 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. Find the head H the pump must add.

Q = 40 L/sΔz = 25 mL = 100 mD = 150 mmf = 0.018ΣK = 8
H = m

Answer key

  1. 1. Ph = 3 kW
  2. 2. Ph = 1.648 kW
  3. 3. Pshaft = 17.95 kW
  4. 4. Pel = 61.09 kW
  5. 5. H = 35.7 m
  6. 6. H = 30.22 m

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