Compute available NPSH for a pump suction line including line losses: NPSHa = (P_tank - Pv)/(rho·g) + z_static - h_friction, where suction-line friction uses Darcy-Weisbach (Swamee-Jain) plus Crane fitting K. The result reports the margin against pump NPSHr and flags cavitation risk.
Inputs
| Parameter | Notes |
|---|---|
| Tank pressure (abs) | Pressure above the liquid |
| Vapor pressure (abs) | At pumping temperature |
| Static head z (m) | + flooded, - lift |
| Suction line L, ID, fittings | Darcy + Crane losses |
| Flow, density, viscosity | Flowing conditions |
| Pump NPSHr (m) | For the margin check |
Outputs
| Output | Basis |
|---|---|
| NPSHa (m) | Pressure head + static - friction |
| Friction head (m) | Darcy + fittings |
| NPSH margin (m) | NPSHa - NPSHr |
| Status | Cavitation / tight / adequate |
Standards & Method
NPSHa balance with suction-line Darcy-Weisbach friction (Swamee-Jain) and Crane TP-410 fitting K-values. Keep margin at least 0.6 m per Hydraulic Institute practice.
Open the Pump Suction NPSH Calculator →
Screening-level preliminary calculation. Verify against project standards and vendor data before engineering use.