control valve basic question 1

[ddtech]

when a control valve is specified as a 12X8 or 4X2 what do these two dimensions mean. One is the line size and the other? thank you

 

[jeebusmn]

My guess is that your looking at the reducer. Control valves will often have a reducer/expander before and after them so that they can use a smaller valve and have greater control.

 

[ddtech]

sorry my first post was not so clear, the line size is 8in in and out, but for the body size its listed as 4x2 special meaning?

 

[ddtech]

fisher ewt body to be exact

 

[JLSeagull]

I don't have a catalog handy. I think that the EW series such as the EWT are cage style globe pattern valves with expanded end connections. The larger number applies to the line size and the smaller number applies to the body size.

The EWT is likely balanced with about FCI Class IV shutoff. I think that these are in-line with larger body expanders to accommodate either noise or cavitation control trim. One of the specialty valve bodies was canted about 30 degrees but I don't think that it was the EW series. The expanded end valves apply to high pressure drop and high velocity applications with larger pipe size due to the velocity. It is common to have the piping a few sizes larger than the control valve but where the reduced piping velocity is still reasonable.

 

[dcasto]

typically the first number is the body size and the second the trim size. The trim size is the diameter of the the actual moving parts or "cage" in the valve.

 

[Ashereng]

dcasto is correct.

A 4 x 2 EWT valve is a 4" body with a 2" trim. (This is nominal, and not exact size.)

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