Fluids and pumps calculators

Pipe pressure drop, pumps, valves and water hammer: the calculations behind most fluid system sizing, with the friction factor and every assumption shown.

• Control valve Cv / Kv sizingLiquid control valve coefficient Kv and Cv to IEC 60534 with the choked-flow and cavitation check, valve opening and pipe velocity.
• Orifice and venturi flow (ISO 5167)Flow from differential pressure for orifice plates and venturis with the Reader-Harris/Gallagher discharge coefficient and expansibility.
• Pipe flow and pressure dropVelocity, Reynolds number, Darcy friction factor (Colebrook, Swamee–Jain) and pressure drop for a straight pipe with fittings.
• Pump and fan affinity lawsFlow, head or pressure and power at a new speed or impeller diameter from one known operating point, with efficiency and specific speed.
• Pump NPSH and suction liftNPSH available from suction conditions, vapour pressure and losses, margin against NPSH required and the maximum suction lift.
• Relief valve sizing (API 520)API 520 required relief area for gas/vapour (critical and sub-critical) and liquid service, with the API 526 orifice letter and margin.
• Water hammer (Joukowsky)Pressure surge from valve closure or pump trip: Korteweg wave speed with pipe elasticity, Joukowsky and Michaud surges, critical time, line pressure check.