Control Valve Pressure Drop

[HardyPatel]

To All:

I want to know how to calculate the pressure drop across control valve for compressible fluid (gas or vapor). I dont want to use fisher CV gas sizing equation as i have Masoneilan Control Valve. Can anyone tell me step by step procedure. I kanow inlet CV pressure, CV of Control Valve, and physical properties of gas flowing through control valve, Gas flow through control valve.

I would appriciate your help.

Hardy

 

[StoneCold]

The fischer valve sizing equations are standardized. They work for any manufacturers valve but if you are against doing that you could use the Masoneilan control valve sizing software.

Regards
StoneCold.

 

[RICARDOARTURO]

Hi Hardy:

In this web page you can find some information about the steps to follow in designing a stpe valve. It can be very helpful.

http://www.cheresources.com/valvezz.shtml

Tell me if it was.

Regards

 

[HardyPatel]

Ricardoarturo,

Thanks for your references, but i went to that site before and i found that it is only for Liquid case they dont have anything for Compressible fluid. It doesnt include expansion factor Y. But i agree that for basic control valve sizing, that is very good information.

To StoneCold,
I can calculate the pressure drop form Masoneilan Control Valve software but i want to know how they calculate it. I mean i want to know the equations used to calculate it.

Thanks
Hardy

 

[STYMIEDPIPER]

This thread in the 'Piping and Fluid Mechanics Engineering' forum may offer some items for consideration

thread378-188854

Hope this Helps!

 

[pleckner]

The Fisher sizing book that you can get on-line at their website not only has all the equations but they give a step-by-step example for both gas and liquids. The equations are all ISA based and thus, as StoneCold said above, are good for any manufacturer's valve.

 

[JLSeagull]

Obtain sizing equations from ISA 75.01.01. Masoneilan also provides sizing software although I don't have it.

 

[TD2K]

Two suggestions. Use the standard ISA equations for control valves or contact Masoneilan and ask for their recommended equations for vapor sizing. This information used to be included in valve catalogs and will still be available even if it's now embedded in a program (or I hope, I know I have talked to some vendors about the background to their canned program and been told they are essentially a black box).

 

[TD2K]

Do a google for "Masoneilan vapor valve sizing equation". Their handbook with the formulas for vapor sizing is at the top of the list, their handbook 0Z1000 7/00 is at the top of their list of hits.

 

[pleckner]

Sorry to be repeating myslef but I don't see the problem with using the Fisher Control Valve handbook. The equations ARE ISA and they give step-by-step examples for both liquid and gas. You do not need a sizing program, the applications of the equations are simple enough. You can even program them into your own spreadsheet without fancy macros.

Here is the link:

http://www.documentation.emersonprocess.com/groups/public/documents/book/cvh99.pdf