VALVE Cv SOLVER

Valve Cv Solver sizes control valves to ANSI/ISA-75.01.01 (IEC 60534-2-1): the flow coefficient required for a target flow, or the maximum flow through a valve of known Cv, with cavitation and choked-flow limits checked in the same calculation.

Capabilities

• Required Cv for a target flow, or maximum flow for a known Cv.
• Liquid and gas service, with phase state determined at line conditions.
• Cavitation, flashing and choked-flow checks.
• Line capacity — the maximum flow the line itself can carry before reaching its API RP 14E erosional velocity, independent of any valve.
• Valve selection from representative body, trim and size candidates, at a chosen ANSI/FCI 70-2 seat-leakage class and balanced or unbalanced trim.
• Actuator force (globe) or torque (rotary) for the selected candidate.
• Side-by-side comparison of shortlisted candidates.
• Exportable PDF report.

Why the results hold up

The core sizing equations are those of ANSI/ISA-75.01.01 (IEC 60534-2-1), with fluid density and phase state taken from the Peng-Robinson equation of state at line conditions rather than entered. Candidate selection applies the standard’s piping geometry factors (FP, FLP, xTP) to each candidate individually, so a smaller valve installed between reducers is assessed against its corrected Cv rather than an uncorrected figure. Actuator sizing follows a published control-valve handbook method for unbalance force and seat load.

Scope

The core Cv calculation assumes line-size installation and high Reynolds numbers; reducer corrections are applied in candidate selection. Cavitation and flashing are assessed by comparing vena contracta and outlet pressures with vapour pressure. This does not replace manufacturer trim-material selection for severe service. The candidate table is a representative handbook set, not a vendor catalogue; confirm the final selection against current manufacturer data. Actuator sizing covers unbalance force and seat load; Class V seat load and packing friction are not calculated. This sizing check is not a substitute for a safety-critical design review; see the Software & Engineering Disclaimer for the suite-wide statement on safety-critical use.