10 replies to this topic

[renin]

how can i size a psv for gas blowby scenario?i need the formula that can be used to get the mass flow through the control valve in an open state for critical and sub critical flow?

[fallah]

renin,

The gas blowby scenario isn't so simple that it can be compressed in one formula by which you can obtain the relevant relief load for PSV sizing!

Try to use some basic references such as API 521 to get my above idea and then in the way you will be trying to obtain the relief load, submit your questions in order to get members assistances.

Fallah

[flarenuf]

hi renin

as Fallah says you need to read and understand

API 521 para 5.10 Failure of process stream automatic controls

this should help you progress to teh next stage

flare e nuf

[Bobby Strain]

And you must consider that the bypass valve might be open, too.

Bobby

[renin]

so how can i get the relief load for gas blowby from the control val formula?i would like to know the control valve formula to use in getting the relief load which can then be used for the sizing

[fallah]

renin,

Try to get Fisher control valve handbook.

Fallah

[renin]

can i get a worked example on gasblowby psv sizing so that i can have a good understanding of this scenario?An excel spreadsheet will be much appreciated. Thank you.

[fallah]

renin,

IMO,understanding a concept, let say analysing a gas blowby case in order to obtain relevant relief load, by using just a worked example is not a right way of learning. In gas blowby scenarios each case has its own characteristics and hardly depends on the conditions of upstream/downstream equipment and the process conditions of the whole system in which the control valve, as the main point of such scenario, is included.

As previously mentioned start to learn from basic references and then in this way (and after that in applying the learned skill on an example) if you would need any help we are ready to do.

Fallah

Edited by fallah, 03 October 2012 - 06:58 AM.

[renin]

thanks a lot for your kind response.i have studied the handbook talked about and i am well aware of the relief load that can be used in getting the size for the Psv. but i believe that one still needs a real life example on gas blowby scenario to really grab the concept and put all that is learned into test. your response would be much appreciated.thank you

[fallah]

renin,

Thanks for your understanding. Now you can submit your specific query on a real example to get the needed help.

Fallah

[renin]

a spreadsheet on gas blowby sizing would be good.