A shuttle valve selects one of two inlet pressure paths to a common outlet while its internal shuttle blocks the opposite inlet. This calculator is an incompressible-liquid Cv sizing reference, not a valve selection or pressure-rating tool.
Shuttle Valve Incompressible-Liquid Cv Reference
Explore an incompressible-liquid Cv sizing reference beside a connected two-inlet shuttle-valve schematic.
Equation Used
- Flow is steady and the liquid is incompressible.
- Specific gravity is referenced consistently with the standard liquid Cv relation.
- Applied pressure drop is capped at inlet gauge pressure to keep outlet gauge pressure nonnegative.
- Viscosity, cavitation, flashing, transients, leakage, materials and ratings are excluded.
Selected Cv utilization is a sizing margin, not predicted shuttle position or valve opening.
Two inlets, one outlet and a translating shuttle
The cutaway shows a ball moving between two opposing inlet seats. Pressure from one inlet pushes the ball against the other inlet seat while supplying the common outlet. The animation alternates the source for explanation and shows flow only in the seated states; entered liquid-sizing data does not determine which inlet wins.
What the calculator determines
Select liquid flow, allowable pressure drop, specific gravity, inlet gauge pressure and desired Cv utilization. The calculator reports required Cv, a Cv with the selected utilization margin, nonnegative outlet gauge pressure and applied pressure-drop percentage.
Incompressible-liquid Cv reference
Applied ΔP = min(selected ΔP, inlet gauge pressure); required Cv = Q√(SG/ΔP); selected Cv = required Cv/utilization; outlet gauge pressure = inlet−applied ΔP.
Selected-input arithmetic
For 12 GPM, 75 psi selected drop, SG 0.87, 2500 psi inlet and 65% utilization, the required Cv is about 1.29 and the selected reference Cv is about 1.99.
Sizing reference only
The liquid Cv relation excludes viscosity correction, cavitation, flashing, compressibility, transient switching, leakage, contamination, seal friction, port geometry, temperature, material compatibility and pressure rating. Manufacturer data and engineering review remain necessary.
Questions
Why can applied drop be lower than the selected drop?
Outlet gauge pressure cannot be negative in this reference, so selected drop is capped at inlet gauge pressure.
Does utilization predict valve opening?
No. It is only a declared sizing-margin convention.
Primary technical references
HAWE: Shuttle valve — ball-seat section and two-inlet, one-outlet operation.
- Parker, Hydraulic Threaded Cartridge Valves catalog — manufacturer shuttle-valve symbol, two-inlet/one-outlet topology, pressure-drop curve and product-specific flow, pressure, leakage, viscosity and temperature data.
Building or designing a mechanism like this?
Explore the precision-engineered motion control hardware used by mechanical engineers, makers, and product designers.
