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Hem Vs. Hne Impact Of Iso 4126 On Psv Sizing For Two Phases

Started by Guest_mdepeche_*, Oct 25 2012 04:42 AM
hem hne psv sizing iso 4126 liquid gas two phases

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#1 Guest_mdepeche_*

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Posted 25 October 2012 - 04:42 AM

I wish to evaluate the impact of HNE (ISO 4126) model over HEM (API Omega) for liquid and two-phase (vapor+liquid) flows,
as I understand the HNE model predicts critical flows in excess of 200% and more over HEM model which will signicantly reduce the size of orifices under certain conditions,
how are engineering companies reacting to this (upcoming) standard ?
Should the decision (about the method to apply) left entirely on the hands of manufacturers ?
We are purchasing several PSV for vapor+liquid service and I have noticed that size of orifices can be very different with ISO-4126

Edited by mdepeche, 25 October 2012 - 04:50 AM.

#2 frpe

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Posted 26 October 2012 - 01:21 AM

as engineering company we apply the standards specified by our clients,
european industries may accept HNE-DS, not sure about US companies,
of course different standards may produce a large impact on parts of a project

#3 PaoloPemi

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Posted 26 October 2012 - 09:49 AM

as said in a different thread I think one should be reasonably safe with the values predicted by HNE models,
according many authors HEM is conservative while HNE models give more accurate results,
a problem being that different manufacturers may offer different solutions and it is not easy to compare,
for those not familiar with HNE models I attach the results of an Excel page distributed with Prode Properties which allows to compare the values calculated with HEM and HNE models,

Attached Files


Edited by PaoloPemi, 26 October 2012 - 09:49 AM.

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