Incompressible-water convention
Liquid valve Cv
Inputs
User-entered valve coefficient under a declared liquid-water convention.
User-entered liquid specific gravity relative to water at the declared condition.
User-entered liquid pressure drop across the valve.
User-entered liquid flow for the reverse required-Cv result.
Results
Flow from declared CvQ
4.7434
Required Cv from declared flowCv
1.4989
1Q = Cv√(ΔP/SG); Cvrequired = Q√(SG/ΔP)
A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.
Nearby: Hydrostatic pressure · Flow continuity · Pipe mean velocity · Bernoulli equation
Method
Formula, when it applies, and when it does not
Convert a liquid-water Cv, pressure drop, and specific gravity to flow, and calculate the reverse required Cv from a liquid flow.
Q = Cv√(ΔP/SG); Cvrequired = Q√(SG/ΔP)
When
- Incompressible liquid only
- Cv water convention
- Declared liquid specific gravity
- No viscosity, cavitation, or recovery correction
Don’t
- This is a liquid-water Cv convention only. Do not use it for compressible air, pneumatic valve sizing, gas flow, flashing, choking, cavitation, viscosity correction, pressure-recovery correction, two-phase flow, or a manufacturer-specific valve rating/test condition. Confirm the supplier’s published flow method before selecting hardware.