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MrPinkFloyd


Registered: 07/13/09
Posts: 683
Loc: United States
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Flowhood Help
#12014820 - 02/12/10 10:07 AM (14 years, 6 days ago) |
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So I called these folks, and they are going to get back to me after he consults the technical adviser(later today/tomorrow).
I have this blower that I was able to score, new, for 30 bucks.
From what I understand, I want at least 100fpm out of the filter, to achieve laminar flow.
So according to the data for the blower, as seen by my link, I want a total static pressure of .6, including the prefilter. I hear prefilters are generally .2 in static pressure (I haven't looked into a prefilter yet), so with that said, I need a HEPA at .4 static pressure, correct? According to the blower's data, .6 static pressure will give me 125cfm(is that the same as feet per minute, as in 100fpm, as stated here. This data sheet is kind of unclear...
Also, what kind of housing should it have? I think just the regular galvanized frame is ok, no header, no gasket, right? I can gasket it myself....right? On second thought, maybe I should get a header on it. Anyway, please help/affirm.
Thanks!
-Mr.Pink
Edited by MrPinkFloyd (02/12/10 10:41 AM)
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wygram
Myconaut

Registered: 01/28/07
Posts: 573
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Quote:
MrPinkFloyd said: I need a HEPA at .4 static pressure, correct?
This is the problem with trying to match filters to fans as opposed to the other way around. You can generally assume that a HEPA filter will have 1" of static pressure. The fan you have will not be able to push enough air for any usable sized filter since it already drops to 125 cfm at only 0.6".
I think you can have a reasonably sized workspace using a 12x24 filter. This means your fan should be able to push 200-250 cfm at 1" of static pressure, so you can have the 100+ linear feet per minute of air leaving the filter.
-------------------- Changing your mind is one of the best ways of finding out whether or not you still have one.
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MrPinkFloyd


Registered: 07/13/09
Posts: 683
Loc: United States
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Re: Flowhood Help [Re: wygram]
#12015021 - 02/12/10 10:50 AM (14 years, 6 days ago) |
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Well shit...
Hmm, soooo am I going to be hard pressed to find a HEPA rated for 99.97%-99.99% with a static pressure of .4?
It's starting to look like this blower needs to be used on a 55gal drum humidifier, ducted into my greenhouse, huh?
Edited by MrPinkFloyd (02/12/10 11:12 AM)
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nachohippie
asshole



Registered: 09/19/09
Posts: 2,623
Loc: right around the corner
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send guns, money ,lawyers, and drugs its been a long night everything i post is a lie im a pathological liar
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MrPinkFloyd


Registered: 07/13/09
Posts: 683
Loc: United States
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Yeah, I've seen this before. Upon rereading it though, I found a flaw in my math, thanks for that I guess.
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MrPinkFloyd


Registered: 07/13/09
Posts: 683
Loc: United States
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Ok.
So if I want a 2ftx2ft work area, with 100ft/min (minimum air speed for laminar flow) I need at least 400cfm at the sum of the static pressure of both filters?
What is the maximum air speed for laminar flow? 200ft/min?
If that's right, maybe I can shoot for a blower that will give me 200ft+/min at maximum power(800CFM at static pressure?), then get a motor contoller, dial down CFM to 100ft/min air speed(400CFM) at the filter face, then down the line, as things get dirty and gummed up, I can increase CFM...?
Edited by MrPinkFloyd (02/12/10 12:53 PM)
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nachohippie
asshole



Registered: 09/19/09
Posts: 2,623
Loc: right around the corner
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sounds good wana sell your 400 cfm fan??
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send guns, money ,lawyers, and drugs its been a long night everything i post is a lie im a pathological liar
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wygram
Myconaut

Registered: 01/28/07
Posts: 573
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Quote:
MrPinkFloyd said: Ok.
So if I want a 2ftx2ft work area, with 100ft/min (minimum air speed for laminar flow) I need at least 400cfm at the sum of the static pressure of both filters?
What is the maximum air speed for laminar flow? 200ft/min?
If that's right, maybe I can shoot for a blower that will give me 200ft+/min at maximum power(800CFM at static pressure?), then get a motor contoller, dial down CFM to 100ft/min air speed(400CFM) at the filter face, then down the line, as things get dirty and gummed up, I can increase CFM...?
For a 24x24 filter you want at least a 500 cfm fan at close to 1", which allows you to have about a 20% reserve for resistance and prefilter without having to calculate static pressure exactly.
I'm not sure about a maximum for laminar flow, but 200 ft/min seems excessive unless you scale it back.
Overbuilding by that much will probably cost you quite a bit for a blower capable of delivering 800 cfm at 1". And if you're using a prefilter it doesn't seem necessary to build for that much power loss as most of the large dirt responsible for clogging the HEPA will get trapped in the cheap prefilter that can be easily replaced.
A 500 cfm at 1" fan would be perfect for a 24x24 filter without using a speed control and a 600 would give you a little more room to work with.
-------------------- Changing your mind is one of the best ways of finding out whether or not you still have one.
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MrPinkFloyd


Registered: 07/13/09
Posts: 683
Loc: United States
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Re: Flowhood Help [Re: wygram]
#12015786 - 02/12/10 01:35 PM (14 years, 6 days ago) |
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Right on. Thanks brother!
As for the gentleman who wants to buy this blower, I don't think so. I'm going to try to use it on a home-made 55gallon ultrasonic humidifier, unless you want to buy if for retail price, plus shipping. So basically, 100.00 plus shipping. I'll assume no.
Seriously though, if this plan doesn't work out, I'll reconsider.
Edited by MrPinkFloyd (02/12/10 01:43 PM)
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nachohippie
asshole



Registered: 09/19/09
Posts: 2,623
Loc: right around the corner
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send guns, money ,lawyers, and drugs its been a long night everything i post is a lie im a pathological liar
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quadracer
Porcini Hunter



Registered: 12/14/08
Posts: 596
Loc: Here, Now
Last seen: 1 month, 7 days
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A few questions:
Does the HEPA filter need some sort of header or ledge to better fit in the cabinet?
Can a HEPA filter from a "Negative Air Machine" be suitable for a laminar flow hood?
Is 480 CFM @ 1" S.P. enough for laminar flow using a 24" x 24" HEPA?
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