Process Pump Power and Annual Energy Cost Calculator
Transfer pumps in a chemical plant run for thousands of hours a year, so a few kilowatts matter. Enter flow, head and density to get hydraulic, shaft and electrical power, then see what the pump costs to run each year.
Your numbers
Sulfuric acid 98% is about 1840, ethanol about 790, water 1000.
Static lift plus friction losses plus pressure difference converted to metres of liquid.
Your results
Assumes a Newtonian liquid and a single duty point. Viscous fluids reduce pump efficiency, so apply the manufacturer's correction. Select the motor with margin above the shaft power at the worst operating point.
Shaft and electrical power vs differential head
Sweeps Total differential head from 5 to 80, holding your other inputs fixed.
Link equipment run hours to production orders
Optional: a short review of how utilities and run hours reach your ERP.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the flow in cubic metres per hour and the total differential head in metres of liquid. Include static lift, friction losses in pipe, valves and fittings, and any pressure difference between source and destination converted to head. Set the pump efficiency from the vendor curve at that duty point. The chart shows how power rises with head so you can test valve throttling.
The formulas
Hydraulic power in kW equals flow in m3/s times density times 9.81 times head, divided by 1000. Shaft power divides that by pump efficiency. Electrical input divides again by motor efficiency. Annual energy is electrical kW times hours, and cost is energy times tariff. Density matters: a pump moving acid at 1840 kg/m3 needs almost double the power of water for the same head.
- Head is independent of density, power is not
- Pressure rise in bar = head x density x 9.81 / 100000
- Operate near best efficiency point for lowest energy
- A VFD usually beats throttling for variable duty
Common mistakes
Using the water curve for viscous or dense products leads to an undersized motor. Forgetting the extra head from a pressurised receiver is another. Efficiency also drops far from the best efficiency point, so a pump running at half the designed flow can consume much more energy per cubic metre than the table suggests.
- Check NPSH available for hot or volatile liquids
- Add margin for fouled filters and ageing pipework
- Use compatible seals and materials for corrosive fluids
- Log run hours from your CMMS or MES to refine the cost
Frequently Asked Questions
What is total differential head?
It is the energy per unit weight the pump adds: static lift, plus friction loss, plus the pressure difference between discharge and suction vessels expressed as metres of liquid. It sets the duty point together with flow.
Why does density change power but not head?
Head is in metres of the liquid being pumped. A denser fluid weighs more per cubic metre, so lifting the same volume the same height needs more energy. Pressure rise scales with density, power too.
What pump efficiency should I use?
Read it from the pump curve at your duty point. Typical centrifugal process pumps run between 50 and 80 percent. Small pumps and off-curve operation are lower, large pumps near best point are higher.
Does it handle viscous fluids?
Only approximately. High viscosity lowers flow, head and efficiency, so apply the Hydraulic Institute correction factors or ask the vendor for a corrected curve before selecting the motor.
If you want pump run hours and energy per batch tied back to production orders, Netray can help join MES and ERP data. Ask us for a review.
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