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Pressure / Vacuum Valve Tolerance


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#1 bevjones

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Posted 15 February 2021 - 04:35 PM

Hi all,

 

{edit} - I've just noticed I may have put this in the wrong section, sorry.

 

I am just wondering if a PVRV has a +/- % tolerance on the set pressure?

I know they have leak rate stipulations (API 2000) but I'm interested if they have.

 

Many thanks

 

Bev


Edited by bevjones, 15 February 2021 - 05:33 PM.


#2 Pilesar

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Posted 15 February 2021 - 06:00 PM

Tolerance is part of the capacity certification procedure. As I understand it, PRVs are allowed to simmer at 98% of set pressure and also allowed 3% overpressure. There are good references by relief valve manufacturers that you might enjoy. Look for the Crosby Engineering Handbook on the internet for example.



#3 breizh

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Posted 15 February 2021 - 07:20 PM

Hi,

Consider this resource , page 3-16 

another link:

https://www.eng-tips....cfm?qid=460584

Good luck

Breizh 


Edited by breizh, 16 February 2021 - 12:58 AM.


#4 fallah

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Posted 15 February 2021 - 11:36 PM

 

{edit} - I've just noticed I may have put this in the wrong section, sorry.

 

I am just wondering if a PVRV has a +/- % tolerance on the set pressure?

I know they have leak rate stipulations (API 2000) but I'm interested if they have.

 

 

Hi Bev,

 

The acceptable tolerance range for set pressure (vacuum) test of PVRVs is +/- 10% which can be applied as tolerances of setting PVRVs in operation too.



#5 bevjones

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Posted 16 February 2021 - 09:51 AM

Thanks everyone.

 

I've been reading up and looks like tanks that fall under API 620 & 650 the tolerance would be equal to or less than the set pressure for both pressure and vacuum. Does this sound correct or do I have my wires crossed?



#6 latexman

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Posted 16 February 2021 - 10:11 AM

It would help if you quoted the language that led you to believe this.



#7 bevjones

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Posted 16 February 2021 - 12:04 PM

I found it here: https://www.cheresou...ure/#entry96768



#8 latexman

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Posted 16 February 2021 - 02:05 PM

 

That thread is not about the "tolerance" of the set pressure of a PVRV.  It is about the "overpressure" and "allowed accumulation" of an API-620 or API-650 tank.  See the definitions of  "overpressure" and "accumulation" and "maximum allowed accumulation" in breizh's attached file in post # 3.  I understand the confusion because these words are closely related, but you have to master these definitions so you can ask the right questions and understand the right answers.  It is not easy, even for me.



#9 bevjones

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Posted 16 February 2021 - 02:38 PM

 

 

That thread is not about the "tolerance" of the set pressure of a PVRV.  It is about the "overpressure" and "allowed accumulation" of an API-620 or API-650 tank.  See the definitions of  "overpressure" and "accumulation" and "maximum allowed accumulation" in breizh's attached file in post # 3.  I understand the confusion because these words are closely related, but you have to master these definitions so you can ask the right questions and understand the right answers.  It is not easy, even for me.

 

Ah.

 

So, talking about overhaul and maintenance. Is there a given tolerance on the set pressure on both positive and negative pressure on a tank breather valve?



#10 latexman

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Posted 16 February 2021 - 02:44 PM

I defer to fallah's answer because I am not on the maintenance end of things.  He said +/- 10%.  So for a set pressure of 1 kPag, it would be acceptable for the PVRV to open anywhere between 0.9 to 1.1 kPag.

 

Also, see breizh's link to Eng-Tips.


Edited by latexman, 16 February 2021 - 02:49 PM.


#11 bevjones

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Posted 16 February 2021 - 03:19 PM

Thanks very much.



#12 bevjones

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Posted 03 March 2021 - 08:57 AM

 

 

{edit} - I've just noticed I may have put this in the wrong section, sorry.

 

I am just wondering if a PVRV has a +/- % tolerance on the set pressure?

I know they have leak rate stipulations (API 2000) but I'm interested if they have.

 

 

Hi Bev,

 

The acceptable tolerance range for set pressure (vacuum) test of PVRVs is +/- 10% which can be applied as tolerances of setting PVRVs in operation too.

 

Hey Fallah, please may I ask where you get these tolerances from? Is there any standards to support it?






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