Need advice on Pressure Equalization

[giggg]

Dear All,

Need your expert advice on this phenomenon:
Say, N2 supply is 60barg.
There is a mechanical PCV which will reduce the pressure down to 17barg.
1 meter downstream of this PCV there is a block valve.

If we close the block valve, will the pressure upstream and downstream of the PCV be equalized to 60barg?

Thank you very much in advance.

 

[itsmoked]

It should not equalize to 60. It may be slightly higher than 17barg because of overshoot if the blocking valve were shut off suddenly during flow.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LittleInch]

If the PCV doesn't seal 100 % then it will equalise. Due to their use, many control valves do not seal and in general can't be relied on to seal.

Speed of response might be an issue here as well.

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

 

[katmar]

For the reasons given by LittleInch I would prefer to put the block valve upstream of the PCV. The piping and equipment downstream of the PCV should either be designed for 60 bar or it should be protected with a relief valve.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[BigInch]

Agree with LittleInch and Katmar. Be safe and consider that the pressure everywhere will rise to that of the supply. Unless you can absolutely quarantee that a control valve (with no pressure relief valve downstream, set at 17Barg or lower) will always function properly and hold that downstream pressure to <= 17Barg, you must consider that the 60Barg supply pressure can be developed at all points.

 

[bimr]

It depends on the type of mechanical PCV (which you have not stated).

 

[georgeverghese]

It also depends on whether the leak rate through the block valve is more or less than that from the leak rate through the " closed " PCV.

 

[davefitz]

If you are trying to reduce the design pressure of the downstream piping and block valve to something below 60 barg, the PCV will not allow you to safely meet that objective; you would need to add enough safety valves to relieve the casualty flow thru the PCV valve. It is likely less costly to retain the 60 barg design pressure on the downstream components.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick