Instrumentation Key equations for Process Engineers Miscellaneous

Flow Coefficient

Flow coefficient of a device represents the ease for a fluid flow to pass through the device. High flow coefficient of a device such as restriction orifice or a control valve indicates low resistance to the passage of flow. Similarly low coefficient indicates higher resistance to the passage of flow and high pressure drop for a given flow.

Mathematically flow-coefficient can be defined as,

Cv = Flow coefficient

V = Volumetric flow

ρ = Fluid density

ΔP = Pressure drop

Depending on the different units used for each of the term on right side of the equation, range of values for flow-coefficient (Cv) changes. Sometimes specific gravity of a fluid can be used instead of the density.

A flow-coefficient (Cv) is a commonly used parameter for the design of flow devices like control valves, flow meters, sprinklers etc.


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