17 April 2026 at 06:32

Pump Sizing

Calculate pump differential pressure, differential head, NPSH available, and absorbed power including pipe friction losses.

Pump Sizing Calculator Guide (PDF)

This calculator is used to size pumps. The calculator determines the total differential head of the pump and the absorbed power required. Frictional and static pressure drops in the suction and discharge lines are also calculated as well as the NPSH available.

Frictional and static pressure losses are determined for the suction side and discharge side of the pump. NPSH available, including a user specified margin if required, is also calculated.

  1. Enter the pump and vessel tag numbers
  2. Enter the barometric pressure at the pump
  3. Enter the margin over the basic NPSH available, if required
  4. Enter the pump efficiency
  5. Enter the fluid details and physical properties
  6. Enter the suction and discharge vessel gas pressures
    • Set the suction vessel pressure to 0 barg if the pump is pumping from atmospheric pressure
    • Set the discharge vessel pressure to 0 barg if the pump is pumping to atmospheric pressure
  7. Enter the suction and discharge static heads
  8. Choose the nominal diameter and schedule of the suction and discharge lines
  9. The calculator will determine the inside diameter of each line
  10. Enter a length for the suction and discharge lines
  11. Enter an absolute roughness for each pipe. Typical values:
    • Commercial steel: 0.046 mm
    • Drawn tubing (brass, lead, glass): 0.002 mm
    • Asphalted cast iron: 0.122 mm
    • Galvanized iron: 0.152 mm
    • Cast iron: 0.259 mm
  12. Enter the quantities of each type of fitting for each pipe if known
  13. If the type and quantities of each fitting are unknown, enter a fitting factor. Typical factors for 50 metre long lines:
    • 3" diameter and smaller: 1.5
    • 4" and 6" diameter: 2.0
    • 8" diameter and larger: 2.5
  14. Enter a discharge control valve differential pressure if a control valve is fitted in the discharge line
  15. Click the "Calculate" button
  16. The calculator will determine the total differential pressure and power required to pump the specified fluid
  17. The NPSH available will also be calculated
Pump Sizing Diagram
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PUMP DETAILS
Pump tag number  
Suction vessel tag number  
Discharge vessel tag number  
Barometric pressure Patm
NPSH available margin Hmargin
Pump efficiency η %
FLUID PROPERTIES
Fluid  
Phase  
Flowrate m
Density ρ
Viscosity μ
Vapour pressure Pvap
VESSEL GAS PRESSURES
Suction vessel gas pressure Psuc. vessel
Discharge vessel gas pressure Pdis. vessel
STATIC HEADS
Suction static head Hsuc. static
Discharge static head Hdis. static
PIPELINES
Suction Line Discharge Line
Pipe nominal diameter   inch
Pipe schedule  
Pipe internal diameter d 6.8 6.8 mm
Pipe length L
Absolute roughness e
FITTINGS
Quantities Suction Line Discharge Line
90° LR bends
90° Std elbows
45° LR bends
45° Std elbows
Straight tees (flow thro' run)
Straight tees (flow thro' branch)
Pipe entrances
Pipe exits
Pipe contractions
Pipe expansions
Gate valves
Globe valves
Swing check valves
Lift check valves
Tilting disc check valves
Stop check valves
Poppet foot valves (with strainers)
Hinged disc foot valves (with strainers)
Ball valves
Butterfly valves
Plug valves
Miscellaneous losses (no. velocity heads)
Fittings factor
DISCHARGE CONTROL VALVE
Control valve differential pressure ΔPCV
OUTPUTS
Volumetric flow rate Q 10.0
Suction Line Discharge Line
Relative roughness e:d 0.00676 0.00676
Flow area A 4e-05 4e-05
Velocity u 76.49 76.49
Reynolds No. Re 520114.0 520114.0
Flow regime   turbulent turbulent
Friction factor f 0.03358 0.03358
Pipe velocity head loss Kpipe 0.0 0.0
Fittings total velocity head loss Kfittings 0.0 0.0
Frictional pressure loss ΔPfriction 0.0 0.0
Frictional head loss Hfriction 0.0 0.0
Pump suction pressure Psuction 1.01
Pump suction head Hsuction 10.33
Pump discharge pressure Pdischarge 1.01
Pump discharge head Hdischarge 10.33
Net positive suction pressure available PNPSHA 0.9
Net positive suction head available NPSHa 9.12
Pump total differential pressure ΔPpump 0.0
Pump total differential head Hpump 0.0
Pump absorbed power E 0.0
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