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Calculator start selection

Read all about available
deployments.
In any way of utilizing calculator, Internet connection is required, for authentication at least.

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Available in download version

save/open multiple results

export to word and excel

print results

custom fluid properties

K factor for fittings, resistance coefficient

pipe surface roughness selection

select between gauge and absolute pressure

compressible isothermal flow

dry air isothermal flow

gas offtake flow

natural gas flow

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When is this calculator suitable?

To select a size of a control valve, you should calculate the required
flow coefficient Cv/Kv for the flow rate and pressure drop.

For a specific control valve, flow coefficient Cv/Kv is determined experimentally
by control valve manufacturers, and you can found it in manufacturers technical specifications.

They express coefficient Cv/Kv as the flow rate of water in g.p.m. [m3/h] for a pressure drop of 1 psi [1 bar] across a flow passage [flow coefficient: Cv-imperial, Kv-metric].
You can use the calculator to calculate maximum flow rate through control valve for given
pressure drop and known flow coefficient of control valve Cv. With maximum flow rate calculated,
you can compare control valves from different manufacturers for their efficiency for the same
nominal size.

Control valve calculator is suitable for turbulent flow of liquids.

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When is this calculator not relevant?

Flashing, cavitation, and chocked flow may reduce the control valve capacity.
That calculation is not in this version of control valve calculator.

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How is the calculation executed?

The calculator is calculating flow coefficient Cv/Kv using the relationship between
pressure drop and flow rate in the control valve which is for complete turbulent flow
following power law where flow coefficient Cv/Kv is the proportional constant:

where is:

q - flow rate

Cv - flow coefficient

Δp - pressure drop

S - specific gravity (relative density)

# Need a helping hand?

If you need a quick calculation, but you are not still familiar how to use the calculator, you
can order calculation service from the calculator developer.