This information is part of the Modelica Standard Library maintained by the Modelica Association.

This characteristic is such that the relative change of the flow coefficient is proportional to the change in the opening position:

d(rc)/d(pos) = k d(pos).

The constant k is expressed in terms of the rangeability, i.e., the ratio between the maximum and the minimum useful flow coefficient:

rangeability = exp(k) = rc(1.0)/rc(0.0).

The theoretical characteristic has a non-zero opening when pos = 0; the implemented characteristic is modified so that the valve closes linearly when pos < delta.

rc = equalPercentage(pos, rangeability, delta)

pos	Type: Real Description: Opening position (0: closed, 1: fully open)
rangeability	Default Value: 20 Type: Real Description: Rangeability
delta	Default Value: 0.01 Type: Real

rc	Type: Real Description: Relative flow coefficient (per unit)