What this tool does
Estimate the system-side suction head above water vapor pressure and keep absolute pressure, static suction condition and temperature visible.
When to use it
Use it after suction geometry and losses are known. Compare NPSHA with manufacturer NPSHR and an application-specific margin.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
Positive static suction head means the liquid surface is above the pump; a suction lift is entered as negative. Water properties are limited to 0–100 °C.
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
At 101.325 kPa absolute, 2 m flooded suction, 1.5 m friction and 20 °C water, NPSHA is about 10.6 m before any additional loss.
Assumptions
Water only; steady inlet conditions; pressure is absolute; pump reference elevation is used consistently.
Limitations
No acceleration head, dissolved gas, non-water property or transient suction analysis is included.
Sources
- Hydraulic Institute — Pump Principles and NPSH
- NIST — Thermophysical Properties of Fluid Systems
- Hydraulic Institute — Pump FAQs