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MicroMycelium
Curious Optimizer


Registered: 06/06/23
Posts: 461
Loc: Probably at work
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Re: Box fan flowhoods, Glove boxes, Positive pressure boxes and Automated Mono-Tubs [Re: Stipe-n Cap]
#28482163 - 09/25/23 09:41 AM (4 months, 23 hours ago) |
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If I were to build my hood with a Hepa pre/intake filter attached to the blower, and a standard high-MERV rated workspace filter on the workside, would it be effective as effective as the reverse? (assuming the CFM provided enough pressure)
It seems financially smarter as a hepa intake filter may cost 40-60$ and MERV 24x24 filter around 40$ as well. Comparative to larger 24x24x2 H14/H13 hepa filters costing near 200$ for the filter itself if the other way around.
Assuming the air comping it was hepa filtered, and the box containing the airflow was gasketed/sealed, there shouldn’t be anything foreign introduced before being diffused over your work area.
I see the Grainger blowers are recommned ex: 1TDT2 At around 190$ the 1TDT2 however only has a max CFM of 538. Compared to: $180 for AC Infinity Pro S8 with max CFM of 807 Or if strong enough, $40 gets 428 CFM with the AC Infinity Raxial S8
To save desk space with less depth on the FFU an inline duct fan would be placed laterally in the box, perpendicular to the filter like in Gordo’s knock off of 7sun’s poor man’s TEK.
Is a blower more beneficial because it can push air directly toward the filter for less turbulence compared to perpendicular airflow moving around more internally before exiting?
Edited by MicroMycelium (09/25/23 10:29 AM)
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MicroMycelium
Curious Optimizer


Registered: 06/06/23
Posts: 461
Loc: Probably at work
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Re: Box fan flowhoods, Glove boxes, Positive pressure boxes and Automated Mono-Tubs [Re: Stipe-n Cap]
#28482445 - 09/25/23 02:34 PM (4 months, 18 hours ago) |
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Quote:
Stipe-n Cap said: Why doesn't this "budget flowhood" work? Well, remember that laminar flow is required which is the product of resistance, velocity, and geometry; furthermore the filter is not designed to filter out microscopic particles with high efficiency.
A blower attached to a filter, or set of filters, would be more aptly called a "blowhood". The particle sampling data clearly illustrates how ineffective the standard hardware store filters are when it comes to filtration efficiency.
3. The filter does not produce enough resistance and does not possess the correct internal geometry to align the airlflow into lamina.
As a result you're left with a turbulent flow machine that sucks in contaminant particles, (maybe the filter catches some of the larger debris like cat hair, etc) but ultimately blows microscopic particulate all over your work area.
Quote:
Stipe-n Cap said: See the particle filtration sampling data listed in the OP.
I missed that part, thanks.
So if I’m interpreting this correctly, Regardless of how clean the air is, it is the relative resistance of the filter facing your workspace that cause the turbulent internal air to diffuse into a laminar flow?
So essentially both a blower/fan can actually have much CFM even with the proper filtration, and if there isn’t enough of a pressure drop/resistance from your exhaust filter the air won’t be moving in a laminar flow?
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