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5280R
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Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter?
#28478449 - 09/22/23 08:22 AM (1 year, 3 months ago) |
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I'm working on a custom laminar flow hood and I feel like MAYBE I just had a great idea. I've been trying to find an inexpensive H13 or H14 HEPA filter that fits my exact size needs but am coming up short because you basically need to find an air purifier that randomly uses the exact size you need.
Then it hit me- maybe I can have the blower fan blasting air into the HEPA filter, into the box cavity, and then use the perfect size 2" or maybe 4" deep furnace filter at the exit? So the air is clean, and I get to use the perfect size filter since furnace filters are made in a hundred easily found sizes.
Would that work okay? In my mind I can't see why not. Can people with bigger brains than me please weigh in? Thanks!
My terrible rough sketch:
Edited by 5280R (09/22/23 08:24 AM)
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RockinRobot
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: 5280R]
#28478455 - 09/22/23 08:31 AM (1 year, 3 months ago) |
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No furnace filter will provide laminar flow.
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Mycolorado
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: RockinRobot]
#28478458 - 09/22/23 08:36 AM (1 year, 3 months ago) |
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The real issue is the efficacy of those filters. For our purposes, we shoot for filters with 99.97-99.99% efficiency down to .3 microns.
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5280R
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: Mycolorado]
#28478503 - 09/22/23 09:32 AM (1 year, 3 months ago) |
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Quote:
Mycolorado said: The real issue is the efficacy of those filters. For our purposes, we shoot for filters with 99.97-99.99% efficiency down to .3 microns.
Yes, understood, that's why it's first passing through an H13/H14 HEPA filter which meets the standards you've mentioned.
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5280R
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: RockinRobot]
#28478506 - 09/22/23 09:34 AM (1 year, 3 months ago) |
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Quote:
RockinRobot said: No furnace filter will provide laminar flow.
I don't understand why not. Why does a HEPA filter provide it but a furnace filter wouldn't? They're both just pleated paper in the end, right? Is it the thickness of the filter? I mentioned using a deep furnace filter, 2-4".
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Mycolorado
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: 5280R]
#28478513 - 09/22/23 09:40 AM (1 year, 3 months ago) |
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Cool, should work to produce a sterile field.
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RockinRobot
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: 5280R]
#28478544 - 09/22/23 10:18 AM (1 year, 3 months ago) |
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TQuote:
5280R said:
Quote:
RockinRobot said: No furnace filter will provide laminar flow.
I don't understand why not. Why does a HEPA filter provide it but a furnace filter wouldn't? They're both just pleated paper in the end, right? Is it the thickness of the filter? I mentioned using a deep furnace filter, 2-4".
Laminar Flow means that the air currents have no turbulence. Furnace filters are not designed for this. Actual filters for FFUs are designed for this.
Personally unless you are doing bags or massive number of jars a SAB is all you need. If you want a hood invest in a proper FFU filter to begin with. There is already an entire thread dedicated to why what you're trying won't work.
Edited by RockinRobot (09/22/23 10:22 AM)
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Kinoko314
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: Mycolorado]
#28478547 - 09/22/23 10:19 AM (1 year, 3 months ago) |
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Not all hepa filters will produce laminar flow. It depends on the geometry of the filter.
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Mycolorado
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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: Kinoko314]
#28478549 - 09/22/23 10:20 AM (1 year, 3 months ago) |
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…as well as the air moving through it.
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meta_mmxxii



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Re: Working on a budget large laminar flow hood, can I have the fan blow through HEPA and then furnace filter? [Re: Mycolorado]
#28478568 - 09/22/23 10:36 AM (1 year, 3 months ago) |
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I am a retired HVAC tech and what they are saying is absolutely true. Furnace filters are designed to catch large particles Like dust, skin cells and dirt. The particles that make this up are quite a bit larger than say spores or bacteria. A HEPA filter is designed to filter particles that are .3 microns or lower. A HEPA filter is designed a different way then a furnace filter. And a HEPA filter that is designed for laminar flow is designed even different then that. To make a proper LFH it costs about $300 after buying the parts that are REQUIRED to produce Laminar Flow. You are better off just buying one already made that is guaranteed to work. I am just sticking with an SAB, gets it done and cost me like $20 and 20 min. to make. That's my story and I'm sticking to it
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