Control Valve Sizing

Cv / Kv for liquid, gas/vapour and steam service · ANSI/ISA-75.01.01-2012 · IEC 60534-2-1 · validated <0.5% vs the standard worked examples (methodology).

Edition: ANSI/ISA-75.01.01-2012 · IEC 60534-2-1

Flow, Q

Inlet P₁ (abs)

Outlet P₂ (abs)

Vapour pressure Pv

Critical pressure Pc

Density ρ₁

Viscosity μ

Valve size d

Pipe ID D₁

Pipe ID D₂

Rated Cv

Required Cv

190.76

Kv 165· 76% open

FAIL

Sub-critical: service ΔP is below the choked limit.σ=1.33 — likely damaging cavitation; review trim/Δp staging.Required opening 76% within the 20–80% band.

relRho0.9664

dP_kPa460

FF0.9442

dpChoked_kPa497.19

dpSizing_kPa460

sigma1.326

FP1

FLP0.9

FR1

Rev3012128

control-valve-liquid · 1.0.0 — cv→ANSI/ISA-75.01.01 §7.2 / Eq.1–5 (incompressible) · ff→ANSI/ISA-75.01.01 §7.3 FF critical pressure ratio · dpChoked→IEC 60534-2-1 choked liquid flow · sigma→ISA-RP75.23 cavitation index σ

Multi-case (what-if) · turndown 2.6×

Case	Required Cv	Opening
Min	95.378	38.2%
Normal	190.76	76.3%
Max	247.98	99.2%

Inherent characteristic

0% travel100%