Isolation Globe Valve - Linear or EQ%

[EmmanuelTop]

G'Day

I hope to hear some clarification on this subject as I am lacking of any information related to this particular valve.

It is a 1" globe isolation valve, installed on the bypass line around the Thermal relief valve (TRV). Without having any valve datasheet, is there a way to find out if the valve in question is of Linear or EQ% type? We need to do some operational tests and we require certain continuous flow through this valve, so e.g. 30% opening will result in quite different flows for a Linear and EQ% valves.

How to determine the valve characteristic? Sorry if dumb question and many thanks in advance.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[MortenA]

You can do two things imo:

1) Assume "the worst"

2) FInd out what is cheapest and assume thats what has been used

Best regards

Morten

 

[bcd]

Most likely an EQ%. Linear requires a special plug shape which is used for specific applications which are common such as where the upstream and downstream pressures are constant regardless of the valve opening. For valve bypass, EQ% is all that is needed so that is why I suspect that is what is installed. The only ways to be sure are to check with the valve manufacturer or to remove the plug and look at it.