5 replies to this topic

[Ankit_Kumar]

Hi there,

 

I need to calculate Cv of an existing valve for a gas service at increased flow.

I searched on this forum and found two excel sheets. I have used and found Cv value to be different from each other.

Has anyone used these excel sheets? If yes, what is your feed back.

If No, can you just check the data with your software/excel sheets and see the results are same or different.

 

Regards

 Sizing through Cheresources sheet.pdf   287.21KB   130 downloads

Attached Files

•  asd.xls   172KB   115 downloads

[breizh]

Hi ,

Why don't you ask reputable vendor ? they will be happy to support you .

 

You can find literature in this forum using the search engine and of course you can download from internet good software for such calculation ,as an example NorriSize .

 

Good luck .

Breizh

[Ankit_Kumar]

Thanks Breizh

 

I was new to this topic so i found the standard ISA_750101_SPBd and matched it with excel sheet (i found on this forum).

 

Not only the results are same but also i got the understanding why there is difference in two sheets.

 

Regards

[breizh]

Hi ,

Thanks for sharing your work .I've added a calculator you may consider to support .

 

http://www.pipeflowc...m/controlvalve/

 

Good luck

 

Breizh

[Erwin APRIANDI]

 

Hi Ankit,

 

I'm reading on your posting above and I'm trying to understand the challenge here.

 

From your posting above what I understand is you have and existing valve (this valve already have a rated Cv) and you wanted to check whether or not this Cv is still enough for the increased gas flow.

 

First thing that you have to check if what is the your current control valve manufacture and also type. Cause each Control Valve manufacture has his own different formula based on the characteristic of the valve that they manufacture so to be able to have on the same basis with how the current control valve is sized you have to use the same formula.

 

If you cannot have the data of the existing control valve, one that you can use is by using the existing general Cv sizing formula, the formula can be found in several engineering guideline or standard. But be aware that the calculations that you use may be different with the calculation that is have been used to calculate the current control valve Cv, so it is like you are comparing Apple to Orange here.

 

The validity of any method that you used, whether to try to use the same formula as before or to use generic control valve sizing will be depend on the stage of you problem. If this is to be applied on the operations I would prefer to try to find the current valve manufacture control valve sizing formula, but if this is for feasibility study you can use the generic control valve sizing.

 

Hope the answer is helping

[Ankit_Kumar]

Thanks All.

 

@Erwin,

 

Formula remained same for each manufacturer but the value of certain contants like FL, Fp, XT etc. change depending on manufacturer.

Rest wht you said is right and i did the same.

 

Regards