Equal Percentage Valves

Equal Percentage valves have a valve plug shaped so that each increment in valve percent open (lift) increases the flowrate by a certain percentage of the previous flow.

The relationship between valve lift and orifice size is not linear but logarithmic.

It is expressed mathematically as follows:

where:

  • τ = valve rangeability (ratio of the maximum to minimum controllable flowrate)

  • H = valve percent open or lift (0 = closed; 1= fully open)

  • Cv,max = full open valve loss value

Related Topics

General Junction Information

Two Window Formats

Common Junction Input Parameters

Optional Input for Junctions

Specifying Losses

Conventions for Specifying Basis Area

Reference Density