Cv Flow Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Fluid calculations are especially sensitive to density, viscosity, geometry, pressure conventions, and unit systems. Cv Flow Calculator narrows that problem to the relationship used on this page, making the displayed cᵥ flow easier to audit against the inputs and the governing equation.

What this calculator does

The Cv Flow Calculator uses Specific gravity to estimate the page’s Cᵥ flow from the fluid-mechanics relationship below. It is meant for a defined geometry and property set, so the useful part is not just the headline number but also whether your density, viscosity, dimensions, pressure reference, and flow convention match the model.

How to use it

Start with the fields that actually drive this result: Specific gravity. Keep units consistent with the menus beside the fields and avoid mixing values measured under different conditions. After calculating, change one input at a time if you are comparing scenarios; that makes cause-and-effect much easier to see.

How the calculation works

For a liquid valve in U.S. customary form, flow is Q(gpm) = Cv√(ΔP(psi)/SG), or equivalently Cv = Q/√(ΔP/SG). The page converts its supported pressure/flow units before applying that relationship.

Example

For a worked liquid example, Cv = 10, pressure drop = 10 psi, and SG = 1 give Q = 10√10 ≈ 31.62 gpm. The current page may show zero when both Cv and flow are blank, so enter one of those quantities before expecting a meaningful solved value.

How to interpret the result

Interpret the Cᵥ flow within the fluid, geometry, pressure reference, and property values you entered. A numerically plausible answer can still be physically wrong if gauge/absolute pressure, diameter/radius, viscosity type, or unit convention is mismatched, so compare the result with the assumptions as well as the formula.

Limitations and notes

With both Cv and flow left blank, the current page can show a zero result even though inlet/outlet pressures are filled. Enter either a known Cv or a known flow and verify the other value; the fluid selector does not automatically set specific gravity.