Pump System Inputs
Formula Used
How to Use This Calculator
- Select the main calculation mode.
- Choose a fluid preset or enter custom properties.
- Enter source, destination, and pump elevations.
- Enter boundary pressures with the correct pressure basis.
- Add every important suction and discharge pipe section.
- Select Darcy-Weisbach or Hazen-Williams for each section.
- Enter NPSH, efficiency, and safety values.
- Review warnings before selecting a pump.
Example Data
| Input | Example value | Purpose |
|---|---|---|
| Fluid | Fresh water at 20°C | Sets density and viscosity. |
| Flow | 18 m³/h | Determines pipe velocity and power. |
| Suction elevation | 0 m | Defines the source liquid level. |
| Discharge elevation | 15 m | Defines the destination liquid level. |
| Suction pipe | 6 m, 75 mm | Calculates suction-side loss. |
| Discharge pipe | 40 m, 50 mm | Calculates discharge-side loss. |
| Pump efficiency | 75% | Estimates shaft power. |
| NPSH required | 3 m | Checks cavitation margin. |
Pump Head and Pressure Guidance
What pump head means
Pump head represents energy added per unit liquid weight. It is commonly expressed in meters or feet. Head remains useful across many pressure and fluid systems.
Head versus pressure
Head is a liquid-column height. Pressure also depends on the fluid density. Denser fluids create greater pressure at identical head.
Static and dynamic head
Static head comes from elevation and boundary pressure differences. Dynamic losses appear while fluid moves through piping. Pump selection should normally use total dynamic head.
NPSH importance
NPSH available describes suction conditions at the pump. NPSH required comes from the pump manufacturer. A positive margin helps reduce damaging pump cavitation.
Frequently Asked Questions
What is pump head pressure?
Pump head is the fluid energy expressed as height. Pressure is the corresponding force per unit area. Density connects head and pressure through the conversion formula.
Does pump head change with fluid density?
Pump head for a given pump curve is largely density independent. The pressure produced changes with fluid density. Heavier fluids require greater power at equal flow.
What is Total Dynamic Head?
TDH combines static, pressure, friction, and velocity effects. It represents the operating head required from the pump. Use TDH when reviewing a manufacturer pump curve.
Which friction method should I use?
Darcy-Weisbach works with many liquids and pipe materials. Hazen-Williams is commonly used for water distribution systems. Use project standards when they specify one method.
What is a reasonable pipe velocity?
Recommended velocity depends on service and system requirements. High velocity increases friction, noise, and surge risks. Review applicable engineering standards before final pipe sizing.
What causes low NPSH available?
High suction lift can reduce NPSH available. Suction friction and hot liquids also reduce it. Lower atmospheric pressure creates another important reduction.
Can gauge and absolute pressures be mixed?
They should not be mixed without conversion. Gauge pressure excludes local atmospheric pressure. Absolute pressure includes atmospheric pressure in its value.
How much safety margin should be added?
The suitable margin depends on uncertainty and operating variation. Excessive margin can cause poor pump selection. Follow owner specifications and experienced engineering judgment.
Are series and parallel estimates exact?
The displayed split is an ideal planning estimate. Real performance depends on combined pump and system curves. Verify final duty using manufacturer performance data.
Can this replace professional pump design?
This tool supports preliminary estimates and engineering checks. It cannot model every transient or installation detail. Critical systems require qualified review and manufacturer confirmation.