7 replies to this topic

[nishantril]

Hello everyone....I have just started my career as a chemical engineer with nearly 3 months of experience in an industry....I have learned that theory and practical knowledge both have a large difference...thus hoping to learn a lot from you all...thanks..!

according to my information butterfly valves are ON OFF valves..similarly gate valves are also used for the same purpose....what is the factor which decides the use of butterfly or gate valve..?

[fallah]

Hi,

 

Some factors affects the usage:

 

Clean service:Gate

Fast action (quarter-turn from full open to full close and vice versa): Butterfly

Frequent opening/closing: Butterfly

................................................................

 

Googling will provide much more info...

[samayaraj]

In general,

 

+ Gate valve: Gradual closing which avoids hammering, available from 1/2 inch & above, pressure drop is less compared to butterfly valve, can be used for high pressure and high temperature service.

- Gate valve: Stem movement is huge and hence requires more effort to operate, for bigger size valve (eg 24 inch above) manufacturing cost is huge, cant use for throttling service, requires integral bypass valve for opening (for larger size valves).

 

+Butterfly valve: 90 deg turn, quick opening/closing, can be used for throttling purpose also, if the seat is of replaceable rubber it would save you money instead of replacing the valve, replacement for gate valve for higher size (eg: 24 inch above), do not require integral bypass valve, optimum for general service application.

- Butterfly valve: Cant be used where gradual open/closing (with gear setup you can operate gradually), commercial available size is from 2 inch onward, more pressure drop compared to gate valve, not recommended for high pressure and temperature.

 

Regards,

Samayaraj

Edited by samayaraj, 22 November 2013 - 01:21 PM.

[latexman]

When line size gets big and you need to control the flow rate, but do not require great control, think of a butterfly valve.  It can save a ton of $ over a globe valve.

[nishantril]

When line size gets big and you need to control the flow rate, but do not require great control, think of a butterfly valve.  It can save a ton of $ over a globe valve.

why is it so?

[nishantril]

Hi,

 

Some factors affects the usage:

 

Clean service:Gate

Fast action (quarter-turn from full open to full close and vice versa): Butterfly

Frequent opening/closing: Butterfly

................................................................

 

Googling will provide much more info...

thanks..!

[latexman]

 

When line size gets big and you need to control the flow rate, but do not require great control, think of a butterfly valve.  It can save a ton of $ over a globe valve.

why is it so?

 

 

Globe valves are more expensive than butterfly valves at any size.  Globe valves require more metal/material, are much heavier, require more machining, have closer tolerances, are more robust, are more precise, etc.  As the line size gets bigger these differences gets huge as does the price difference.

[nishantril]

ok sir thanks