Free · Physics models
Liquid Valve Flow Coefficient Cv
Relate liquid flow, specific gravity and a positive pressure drop to conventional valve Cv.
- Formula & worked example
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
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Formula and method
pressure drop = 100.00; valve flow coefficient = 2.7746. This worked example uses the displayed units and declared assumptions.
valve_flow_coefficient = (flow_rate * sqrt(specific_gravity)) / sqrt(pressure_drop); pressure_drop= inlet_pressure - outlet_pressure; specific_gravity = custom_gravity
Worked example
Enter these known values and leave the other values blank.
- Flow rate
- 40 L/min
- Inlet pressure
- 200 kPa
- Outlet pressure
- 100 kPa
- Specific gravity
- 1
- Pressure drop
- 100 kPa
- Valve flow coefficient (Cᵥ)
- 2.7746
Assumptions and limitations
- Cv uses US gallons per minute and psi differential pressure. This is the incompressible nonchoked liquid relation; cavitation, flashing, viscosity corrections and gas sizing are excluded. Retained customary factors are rounded.
- Clear an unknown to solve a supported inverse; keep known values fixed with locks. Singular or underdetermined inverses may remain incomplete.
Common questions
What assumptions apply?
Cv uses US gallons per minute and psi differential pressure. This is the incompressible nonchoked liquid relation; cavitation, flashing, viscosity corrections and gas sizing are excluded. Retained customary factors are rounded.
Which unknowns can I solve?
Editable controls preserve the supported captured inverse branches. Clear the desired unknown and provide enough independent known quantities; singular or underdetermined inverses may remain incomplete.
References
Forward flow requires inlet pressure greater than outlet pressure.