Control Valve · Glossary

What is a Butterfly Valve?

quarter turn disc valveControl Valve

A butterfly valve is a quarter turn valve with a disc that rotates in the flow path; it is compact and economical for large lines.

Butterfly Valve Explained

Butterfly valves suit large water, air and gas lines at moderate pressure drop. High performance double and triple offset designs give tight shut off.

They have low FL and high pressure recovery, so they cavitate and choke earlier than globe valves.

Butterfly Valve: Typical Values

Typical FL	about 0.55 to 0.7
Useful control range	about 20° to 70° opening

Calculators for Butterfly Valve

CalculatorCv Calculator for LiquidsFree online calculator with formula and worked example.CalculatorCavitation Index CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadControl Valve Datasheet Template in Excel with Cv CheckFree download in Excel and PDF.

Frequently Asked Questions

What is a Butterfly Valve?

A butterfly valve is a quarter turn valve with a disc that rotates in the flow path; it is compact and economical for large lines.

What is a triple offset butterfly valve?

A design with three offsets so the disc seals without rubbing, for tight shut off at high temperature.

Why avoid control near closed?

Torque and gain change sharply near the seat, making control unstable.

Learn more on the blog

Control valve selection: 16 vital factors

A practical guide on instrumentationblog.in with more detail on butterfly valve and how it is applied on real plants.

Read Full Article

More Control Valve Terms

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