EN 60534-2-2:1993

National foreword
Cooperating organizations
Specification
1 Scope
2 Definitions
3 Installation
4 Nomenclature
5 Sizing equations
6 Piping geometry factor FP
7 Expansion factor Y
8 Pressure differential ratio factor xT or xTP
9 Specific heat ratio factor F gamma
10 Compressibility factor Z
Appendices
A Rigorous expression for the expansion factor Y
B Other sizing equations
Tables
I Numerical constants N
II Representative xT values for full size trim at full
    rated opening
AI Values of gamma and sigma gamma
BI Numerical constants N
Figures
1 Pressure tap locations
AI Expansion factor vs. pressure drop ratio for widely
    differing values of Fg (for gamma = 1.4, air)

Presents equations for sizing industrial-process control valves when flowing media are compressible fluids. At very low ratios of pressure differential to absolute inlet pressure, compressible fluids behave similarly to incompressible fluids. The sizing equations presented can then be traced to the basic Bernoulli equation for Newtonian incompressible fluids. However, increasing values result in compressibility effects which require basic equations to be modified by appropriate correction factors. Equations presented are for gas or vapour. Not intended for multiphase streams, e.g., gas-liquid, vapour-liquid or gas-solid mixtures.