Page 48 - Valve Selection Handbook

Fundamentals 35

19
This relationship is contained in IEC Publication 534-1 and applies
to single-phase and fully turbulent flow of Newtonian liquids. For other
flow conditions, see IEC Publication 534-2, Parts 1 and 2.

Interrelationships Between Resistance and Flow Coefficients

Resistance and flow coefficients are interrelated. If one coefficient is
known, the other coefficients can be calculated. These are the interrela-
tionships in which:

d inch = reference pipe bore, inches
d mm = reference pipe bore, mm

Relationship Between Resistance Coefficient and
Valve Opening Position

The relationship between fractional valve opening position and relative
flow through the valve is denoted as flow characteristic. When flow at all