The?size?of?a?butterfly?valve?is?determined?by?a?number?of?factors,?including?the?flow?rate,?pressure,?and?temperature?of?the?fluid

being?controlled.?In?this?article,?we?will?discuss?the?key?considerations?for?sizing?a?butterfly?valve.

Flow?Rate

The?flow?rate?is?the?most?important?factor?to?consider?when?sizing?a?butterfly?valve.?The?flow?rate?is?measured?in

gallons?per?minute?(GPM)?or?cubic?feet?per?minute?(CFM).?To?determine?the?flow?rate,?you?will?need?to?know?the?following?information:

• The?type?of?fluid?being?controlled

• The?viscosity?of?the?fluid

• The?specific?gravity?of?the?fluid

• The?pressure?drop?across?the?valve

Once?you?have?this?information,?you?can?use?a?flow?rate?calculator?to?determine?the?required?flow?rate.

Pressure

The?pressure?rating?of?a?butterfly?valve?is?the?maximum?pressure?that?the?valve?can?withstand?without?failing.?The?pressure?rating?is

typically?expressed?in?pounds?per?square?inch?(PSI).?The?pressure?rating?of?the?valve?must?be?greater?than?or?equal?to?the?maximum

pressure?that?the?valve?will?be?subjected?to.

Temperature

The?temperature?rating?of?a?butterfly?valve?is?the?maximum?temperature?that?the?valve?can?withstand?without?failing.?The?temperature

rating?is?typically?expressed?in?degrees?Fahrenheit?(°F).?The?temperature?rating?of?the?valve?must?be?greater?than?or?equal?to?the?maximum?temperature?that?the?valve?will?be?subjected?to.

Material?Selection

The?material?of?the?butterfly?valve?should?be?compatible?with?the?fluid?being?controlled.?The?following?are?some?of?the?most?common

materials?used?for?butterfly?valves:

• Cast?iron:?Cast?iron?is?a?strong?and?durable?material?that?is?resistant?to?corrosion.?It?is?a?good?choice?for?valves?that?will?be?used?in?corrosive?environments.

• Ductile?iron:?Ductile?iron?is?a?type?of?cast?iron?that?is?more?ductile?than?regular?cast?iron.?It?is?a?good?choice?for?valves?that?will?be?subjected?to?high?pressures.

• Stainless?steel:?Stainless?steel?is?a?corrosion–resistant?material?that?is?also?strong?and?durable.?It?is?a?good?choice?for?valves?that?will?be?used?in?food?or?pharmaceutical?applications.

• Bronze:?Bronze?is?a?corrosion–resistant?material?that?is?also?ductile.?It?is?a?good?choice?for?valves?that?will?be?used?in?marine?applications.

Valve?Sizing

Once?you?have?considered?the?flow?rate,?pressure,?temperature,?and?material,?you?can?use?a?valve?sizing?calculator?to?determine?the?size?of

the?butterfly?valve.?Valve?sizing?calculators?are?available?online?and?from?valve?manufacturers.

To?use?a?valve?sizing?calculator,?you?will?need?to?enter?the?following?information:

• The?flow?rate

• The?pressure?drop

• The?fluid?viscosity

• The?fluid?specific?gravity

• The?valve?material

The?valve?sizing?calculator?will?then?provide?you?with?the?size?of?the?butterfly?valve?that?is?required.

Conclusion

Sizing?a?butterfly?valve?is?a?relatively?simple?process.?By?following?the?steps?outlined?in?this?article,?you?can?select?the?right?valve?for

your?application.

Additional?Resources

• Valve?Sizing?Calculator 1

• Valve?Sizing?Calculator 2

For More Detailed Information, Visit: Lixin Valve Group