Enlarger before PSV?
Enlarger before PSV?
(OP)
ASME states that you should not use an enlarger before a PSV on a vessel. Can someone give me an explanation to why this is?
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RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
I currently have a 3" and need to upsize to a 4". The 4" is not a limiting factor. I'm trying to figure out why ASME will not allow using enlargers inbetween the vessel and PSV.
RE: Enlarger before PSV?
I2I
RE: Enlarger before PSV?
Good luck,
Latexman
RE: Enlarger before PSV?
As @Latexman wrote, it is the Code (ASME) and if your location has adapted ASME as Code then the answer is simply "you have to follow what is written". As to why, you can send a request to ASME as to the explanation for this. Perhaps someone on the ASME committee will write in with the answer. I would think that if the line is only 3" but you need a 4" inlet to the PSV then @dcasto probably has it correct that your 3" line will be a constriction to the required relieving rate. It may also not meet the 3% Rule. Before discounting the pressure drop, perhaps you should go through the calculation.
RE: Enlarger before PSV?
I understand what the code states, thats my reason for posting. I'll see if I can contact ASME and find a solid reason. Thanks for the responses.
RE: Enlarger before PSV?
Aplogy in advance if this is an obvious question to you but when you calculated the pressure drop for the 3% Rule, did you use the stamped capacity of the PSV as you are required to do so? Perhaps you can feed us some details.
RE: Enlarger before PSV?
Doug
RE: Enlarger before PSV?
RE: Enlarger before PSV?
I'm not so sure we can do that. If you look at Bernoulli’s theorem and strike out the elevation terms (because we always do that with gas/vapor flow) and strike out the velocity terms (because that’s where the pressure recovery comes from), we are left with something like:
144P1/ρ1 - 144P2/ρ2 = hL
It looks to me we can only ignore an expander when recoverable and non-recoverable losses are to be evaluated, or am I missing something.
Good luck,
Latexman
RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
Good luck,
Latexman
RE: Enlarger before PSV?
RE: Enlarger before PSV?
RE: Enlarger before PSV?
Good luck,
Latexman