7 replies to this topic

[Tonu]

Hello All,

I know the
a. Back pressure
b. Set pressure
c. Area of cross section
d. temperature of the mixture of gas

I want to calculate the mass flow rate across the valve. Can you suggest me the formula to do so.

Please give me the reference to learn the same, I am new to this field. Any help would be useful.

Thanks,
Tonu

[gegio1960]

try
http://www.cheresour...f-valve-sizing/

[breizh]

Consider these resources to support your query .

A lot of stuff to learn inside those documents.

Hope this helps

Breizh

[Tonu]

Thank you Gegio and Breizh ,

I am confused in the formula given in the crosby manaul (pg 5-3) and the one used in the excel sheet (sub ciritcal flow) , both appears to be different.
Is the one given in the crosby manaul only for the critical flow , what should be in that case the formula for the sub critical flow.(couldn't find it in crosby manaul).
Thanks,
Tonu

[Tonu]

Also another equation (PFA),

Cannot understand the difference between them all,
WHich formula should be used ?
Thanks,
Tonu

Attached Files

•  Flow-Calculation-for-Gases.pdf   18.91KB   32 downloads

[fallah]

Tonu,

All the story is:

There are separate formulas for PSV sizing in critical flow and subcritical flow, but you can use critical flow equation for conventional/pilot operated PSVs sizing in subcritical flow with considering capacity correction due to back pressure effect. The rest is your efforts to realize which formula would be applicable to your special case.

API 520 part I is one of the best sources in which you can find all PSVs sizing formulas for all conditions.

Fallah

Edited by fallah, 13 August 2012 - 06:02 AM.

[breizh]

Tonu ,
To support you we need support from you . Show us your calculation sheet and assumptions you took to solve your query . If it is an existing equipment I will take the tag number of the valve and will check in the maintenance and engineering files where probably data are kept.

Let you try to get a copy of API 520 part 1 as suggested .

Note : This short course should help .

Hope you understand

Breizh

Edited by breizh, 13 August 2012 - 08:23 PM.

[Tonu]

Thanks Breizh,
Shall go through the notes,
Make a excel file and upload the same in some time ,
Thanks for the help,
Tonu