Estimate the irreversible pressure loss across a valve or fitting from its resistance (K) coefficient — the standard method for single-phase, incompressible flow. Computes pressure drop, mean velocity, flow coefficients Cv/Kv, equivalent length and Reynolds number.
Live schematic — fluid flows through the pipe, and the gauges show the pressure drop across the valve in real time.
Resistance-coefficient based pressure loss for valves, fittings and throttling devices.
Ideal single-phase estimate for a fully-open valve. Click Compute or change any input to update.
A valve imposes a local (minor) loss, described by a dimensionless resistance coefficient K. The value depends on valve type, opening fraction and flow direction. Fully-open ball and gate valves have very low K; globe and control valves are much higher.
The resistance coefficient K and the flow coefficient Cv describe the same valve resistance and can be converted. The equivalent-length method turns the valve into an equivalent length of straight pipe at the same frictional loss.