Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

3-Stage Propane Ref Performance

New Blog Entry

Steam Tracing Design- posted in Ankur's blog

1

Psv Nozzle


10 replies to this topic
Share this topic:
| More

#1 Kachisa

Kachisa

    Gold Member

  • Members
  • 61 posts

Posted 14 November 2017 - 10:18 AM

Hi All,

I got a mach number at PSV outlet nozzle  = 1 but 0,7 at pipe outlet.

It is ok ?

 

Thank you



#2 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 2,266 posts

Posted 14 November 2017 - 11:53 AM

We have no idea what you are doing. Maybe you can provide some information so we might help.

 

Bobby



#3 Kachisa

Kachisa

    Gold Member

  • Members
  • 61 posts

Posted 14 November 2017 - 12:08 PM

Dear Mr. Bobby,

 

API recommend to limit mach number of pipe oulet to 0,7 but it does not talk about PSV outlet nozzle.

 

I am checking an existing PSV, and I got a Mach Number at PSV outlet nozzle = 1.



#4 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,389 posts

Posted 14 November 2017 - 12:41 PM

 

I got a mach number at PSV outlet nozzle  = 1 but 0,7 at pipe outlet.

It is ok ?

 

Kachisa,

 

It could be possible in critical flow through the PSV means having sonic flow in PSV orifice which will result in a subsonic flow through the relevant tail pipe due to the back pressure...



#5 Kachisa

Kachisa

    Gold Member

  • Members
  • 61 posts

Posted 14 November 2017 - 12:47 PM

Thanks Mr. Fallah for your comment. 

I got clearly your idea and I totally agree with you.

My worry is not the result, it is rather sound criteria.

 

Another point : the PSV is sized only for fire case.

As fire flowrate is very important, I will use 2 PSV. 

My question is : if these PSV should be staggered ?

I see that is not necessary.



#6 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,389 posts

Posted 14 November 2017 - 12:53 PM

Thanks Mr. Fallah for your comment. 

I got clearly your idea and I totally agree with you.

My worry is not the result, it is rather sound criteria.

 

Another point : the PSV is sized only for fire case.

As fire flowrate is very important, I will use 2 PSV. 

My question is : if these PSV should be staggered ?

I see that is not necessary.

 

If you have to use multiple PSV's to handle the whole relif load they should be staggered.either in fire case or in another case...



#7 Kachisa

Kachisa

    Gold Member

  • Members
  • 61 posts

Posted 14 November 2017 - 01:01 PM

 

If you have to use multiple PSV's to handle the whole relif load they should be staggered.either in fire case or in another case...

 

 

Thanks Mr. Fallah,

2 PSV in service : 1 PSV * 100% + 1 PSV * 105 %

How about the spare PSV, it is set at 100% or 105%, and why ?



#8 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,389 posts

Posted 14 November 2017 - 01:11 PM

 

2 PSV in service : 1 PSV * 100% + 1 PSV * 105 %

How about the spare PSV, it is set at 100% or 105%, and why ?

 

 

Spare PSV should be set same as the main PSV...because it's not intended to be operated simultaneous with the main PSV ..



#9 Kachisa

Kachisa

    Gold Member

  • Members
  • 61 posts

Posted 14 November 2017 - 02:48 PM

Thank you Mr. Fallah,

But PSV 105% may fail ? It is a recommendation from API ?



#10 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,389 posts

Posted 15 November 2017 - 01:27 AM

 

But PSV 105% may fail ? It is a recommendation from API ?

 

Your statement isn't clear; please explain...



#11 demank

demank

    Gold Member

  • ChE Plus Subscriber
  • 145 posts

Posted 15 November 2017 - 09:25 AM

For Fire Case PSV, it is not necessary to install spare PSV.






Similar Topics