Need to find Cv when it exceeds maximum stroke / opening

[kishoredevadoss9704]

In a control valve CV is directly proportional to stroke of valve what happens when stroke exceeds max limit, Say the stroke of the valve maximum is 100% what if it exceeds to 110 % , with the valve fully open.
For example
Valve size %opening Cv

1" 10 0.79
1" 100 13.2
1" 110 ?
Thankyou.

 

[JGard1985]

Doesn't work that way... if its a linear CV, you probably have run out of opening area on your cage (e.g. globe valve) in the valve trim. Any additional stroke doesn't open any additional area.

BTW check your control valve position vs. CV, only certian trims are CV directly proportional to valve position

If its a quarter turn valve (butterfly or ball valve) you could actually be closing (reducing CV) when you go past 100% (Stops usually prevent this)

Jeff
Pipe Stress Analysis
Finite Element Analysis

http://www.xceed-eng.com

 

[LittleInch]

Control valve CV as stated above CAN be equal to linear travel (linear opening) or a variety of other options see

http://www.iceweb.com.au/valve/control valves/determinecharcurve.pdf

I've never seen any control valve capable of opening more than 100%. Simply doesn't happen.

There are control valves of all shapes and sizes - need to be a bit more specific.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kishoredevadoss9704]

Thank you Mr. JGard1985 , Mr. LittleInch, Actually we people in new product development doing R&D i have one last doubt
say for example
Valve type= control valve-linear opening
valve size = 4 inch
Bore= Full bore
Stroke = 2 inch
Maximum Cv= 328
Flow rate = 264 m3/hr
P1=16 bar
P2= 15 bar

My question is if stroke is changed to 2.1 inch Cv differs to 340 and flow rate also changes, and again changing the stroke to 2.25 inch Cv and flow rate remains same as 2.0 inch stroke
i.e Maximum Cv= 328
Flow rate = 264 m3/hr

How and why @2.25 stroke the Flow rate and Cv is same as 2 inch stroke

Thank you

 

[LittleInch]

But what is the control valve type? Globe? Plug and cage? Ball? Gate? Plug?

Give us something to go on here.

"Full bore control valve" ?? Really?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kishoredevadoss9704]

Hi littlte inch, yes it is a Globe type full bore control valve