Control valve Kvs calculator: online

A control valve is sized by its flow coefficient Kv — the flow of water through a fully open valve at a 1 bar pressure drop. Enter flow rate and pressure drop — the calculator computes the required Kv, and checks what flow a chosen Kvs valve will pass.

Fluid and pressure drop

Pressure drop across the valve, ΔPPressure drop — the difference in pressure before and after the valve at the working flow rate. The smaller the drop, the higher the Kv needed. бар Fluid density, ρ water 1000, petroleum products ~800 кг/м³

Sizing Kv by flow

Flow rate, Q м³/ч

Required KvKv — the flow coefficient your flow rate and pressure drop require. It's used to pick a valve with the nearest higher Kvs. — м³/ч

Checking against valve Kvs

Valve KvsKvs — the flow capacity of a fully open valve (m³/h of water at a 1 bar drop), from the nameplate. Take it with a 20–30% margin over the calculated Kv. м³/ч

Flow it will pass — м³/ч

How it's calculated

Kv is the flow of water through a fully open valve at a 1 bar pressure drop. It's the basis for comparing valves against each other.
The required Kv grows with flow rate and falls as the pressure drop increases: the bigger the drop, the smaller a valve can handle it.
Fluid density is factored in relative to water, so the multiplier equals one for water.

Example: A flow of 10 m³/h of water at a 1 bar drop → required Kv = 10 m³/h. A valve with a nameplate Kvs of 16 will pass 16 m³/h at the same drop — a margin of about 60%.

Kv = Q·√(ρrel/ΔP), ρrel = ρ/1000 (water = 1), Q in m³/h, ΔP in bar (GOST 23866 / IEC 60534, turbulent liquid flow). Take Kvs with a +20…30% margin over the calculated Kv.

This is an estimate

Verify final values against current standards, the project design, and equipment nameplates.

Explained in the article Исполнительные механизмы: клапаны, приводы, частотники

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