NPSHa Calculator (Net Positive Suction Head Available)

Pump Sizing, Affinity Laws & NPSH Calculator | growmechanical.com

Pump Sizing, Affinity Laws & NPSH Calculator

Professional quick-selector for process, mechanical, chemical engineers — growmechanical.com

Complete required data • Units visible • Mobile-friendly

Pump Sizing & Design

Flow Rate—m³/h
Total Head—m
Power Absorbed—kW
Pump Efficiency—%
Motor Power (selected)—kW

Motor Power = Power Absorbed × 1.15 (safety & service factor)

Affinity Laws

Q₂ (Flow)—m³/h
H₂ (Head)—m
P₂ (Power)—kW

Q₂/Q₁ = (N₂/N₁) × (D₂/D₁)
H₂/H₁ = (N₂/N₁)² × (D₂/D₁)²
P₂/P₁ = (N₂/N₁)³ × (D₂/D₁)³

NPSHa & NPSHr Margin

NPSHa–m
NPSHr–m
Margin (NPSHa-NPSHr)–m

Margin should be > 1 m for safe pump operation.

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