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Author Topic: Relationship between minimum smoke extraction rate and smoke depth  (Read 1570 times)

kcn283

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Relationship between minimum smoke extraction rate and smoke depth
« on: September 01, 2017, 03:30:22 am »

Hey guys,

I am currently working on some fire and smoke modeling for retail units. So, before I have built my FDS model, I calculated the minimum smoke extraction rate with the ASHRAE AtriumCal excel spreadsheet (download link: http://xp20.ashrae.org/HBofSmokeControl/index.html) So, I have got my reference extraction rate to put into my FDS model. However, I found that the smoke is spilling under the smoke barrier. And thus, I have discovered that the calculated extraction rate (ASHRAE) is not dependent to the smoke depth (Height of extraction point - smoke clear height). So, my question for you guys is, how can we relate the minimum smoke extraction rate to the required smoke depth?

Thank you in advance! ;) ;)
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Erik Carlsson

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Re: Relationship between minimum smoke extraction rate and smoke depth
« Reply #1 on: September 01, 2017, 11:07:21 am »

From memory, the ASHRAE calcs are only rough, provide a minimum value (not maximum), and do not specify where or how your extract is achieved.  You may have to experiment with spreading your extract points in multiple locations to ensure there is no plug-holing, or you may need to increase make up air or similar.  Do you have extract points on the non-fire side of the "smoke barrier"?

There are a number of issues that could be causing the smoke to spread, without seeing the model and detailed inputs it's difficult to help unfortunately.
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Jared

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Re: Relationship between minimum smoke extraction rate and smoke depth
« Reply #2 on: September 01, 2017, 02:58:17 pm »

You will likely get better response if you post this type of FDS specific issue to the FDS discussion forum.  https://groups.google.com/forum/#!forum/fds-smv
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