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 shubrick
 
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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 Another flow hood hepa question 
#16117564 - 04/20/12 09:42 PM (1 year, 28 days ago) |
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Hi all,
I'm struggling to find a filter that is less then 12 inches deep. My interest is finding a filter that's about 6 inches deep so that I can make a flow hood box that doesn't require more than one sheet of 4 x 8 plywood.
My interest in keeping the filter less than 12 inches deep is that as i see it you can't make a box with a deep enough plenum with one sheet. In other words if a 12 inch deep filter requires an additional 24 inches deep of plenum space than you would need more than just 1 4x8 sheet. Ie, you need 4 sides of 2'x3' pieces ( actually maybe a bit bigger by the width of the sheet and kerfs--thickness of saw blade) plus a back panel. By the way, I've got a 4 speed fan that goes up to 12-1300 cfm.
I suppose I could cut some corners and make the Plenum a bit smaller then what is recommended but would rather not.
The only 6" deep hepa I could find was only .70 resistance at 500 cfm.
But I did find a 24"x 24" x 3" hepa rated at .84 wg at 500 cfm and wonder if that would work. Most of the filters I find on eBay have really high cfm ratings for resistances that aren't that close to 1 wg. Most Of them are 12 inches deep, too.
I'm actually thinking of springing for a new one from tridim or fungi perfecti.
So, can a 3 inch deep filter work, assuming appropriate resistances and cfm?
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RogerRabbit
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Registered: 03/26/03
Posts: 39,269
Loc: USA Mountain Northwest
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Re: Another flow hood hepa question [Re: shubrick]
#16119346 - 04/21/12 10:12 AM (1 year, 28 days ago) |
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Order the proper filter and if you need two sheets of plywood, so be it. Saving a sheet of plywood should not be an engineering consideration for a tool you'll use for decades. FP has filters which are suitable for flow hood use.
RR
--------------------
Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
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 Javadog
Continuing along
Registered: 05/03/10
Posts: 7,273
Loc: USA 
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Re: Another flow hood hepa question [Re: RogerRabbit]
#16119889 - 04/21/12 01:40 PM (1 year, 28 days ago) |
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While I was willing to find my fan wherever, and built my ugly hood
myself, I also used FP for the filter. It was too critical to chance.
Good luck,
JD
--------------------
Boyd Rice told my brother that life is a corny pack of freesakes
Myco-tek.org
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EvilMushroom666
Heretic
Registered: 11/18/09
Posts: 10,094
Loc: Canada 
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Re: Another flow hood hepa question [Re: Javadog]
#16119910 - 04/21/12 01:44 PM (1 year, 28 days ago) |
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Tri-dim also offers quality filters, that is where I got mine. They located
what I needed, had it shipped from a depot a few provinces over to them,
and then set up special shipping arrangements so I did not have to pay for
shipping via a courier. If that is the route you are going to go Tri Dim
will treat you well.
RR also brings some valid points to the table.
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GimpCollector
To Drunk To Taste The Chicken
Registered: 02/09/12
Posts: 512
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Re: Another flow hood hepa question [Re: RogerRabbit]
#16120001 - 04/21/12 02:05 PM (1 year, 28 days ago) |
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Dudes eco friendly 
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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I'm waiting on a quote from Tri-dim, actually.
Psychologically I often let "the perfect" get in the way of "the good." By wanting to not waste 30 bucks for extra sheet of plywood, I get stuck.
So, RR's directness is appreciated.
As has been all of the literature in these forums.
Quote:
EvilMushroom666 said:
Tri-dim also offers quality filters, that is where I got mine. They located
what I needed, had it shipped from a depot a few provinces over to them,
and then set up special shipping arrangements so I did not have to pay for
shipping via a courier. If that is the route you are going to go Tri Dim
will treat you well.
RR also brings some valid points to the table.
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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wow TriDim is reasonable [Re: shubrick]
#16129719 - 04/23/12 08:06 PM (1 year, 25 days ago) |
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Just got a quote today for a 24X24X6 hepa, rated at 500 CFM 1" WG resistance and it was very reasonable. I'm still waiting for the shipping quote, but assuming they got the specs right (99.997% at .3 microns), I've been wasting my time looking for filters on Ebay.
Those filters were often manufactured 5-10 years ago (still new, though) and have CFM's at 1500-2000 for resistances below .8
I'd be happy to share what the quote is (after I confirm that they got the specs right), but I'm not sure if that would be frowned upon.
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Terry M
Stranger in a Strange Land
Registered: 06/18/10
Posts: 1,353
Loc: Rhode Island
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Re: wow TriDim is reasonable [Re: shubrick]
#16132204 - 04/24/12 09:40 AM (1 year, 25 days ago) |
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Quote:
Denise85 said:
I suppose I could cut some corners and make the Plenum a bit smaller then what is recommended but would rather not.
I used a very shallow plenum, and have perfectly uniform laminar flow. But I was extremely depth limited at the time. I got lucky. If I had it to do over again, I'd play it safe and follow recommended guidelines.
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Liberté, égalité, humidité.
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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Re: wow TriDim is reasonable [Re: shubrick]
#16137837 - 04/25/12 02:31 PM (1 year, 23 days ago) |
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Here are the specs of the hepa filter. Any worry of 99.97%? I see people referencing 99.997%, which would be different...
3.0 Performance
3.1 Each filter shall have a minimum overall efficiency of 99.97% on 0.3 micron size particles.
3.2 Each filter shall have an initial resistance of 1.00 inches w.g. at a rated flow of 125 Feet per Minute face velocity (500 CFM for a 24” x 24” X 5.875” Filter).
3.3 Each filter shall have a label showing the filter part number, test flow, resistance and filter efficiency.
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
Posts: 39,269
Loc: USA Mountain Northwest
Last seen: 2 days, 23 hours
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Re: wow TriDim is reasonable [Re: shubrick]
#16138223 - 04/25/12 04:29 PM (1 year, 23 days ago) |
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Quote:
shubrick said:
Here are the specs of the hepa filter. Any worry of 99.97%? I see people referencing 99.997%, which would be different...
3.0 Performance
3.1 Each filter shall have a minimum overall efficiency of 99.97% on 0.3 micron size particles.
3.2 Each filter shall have an initial resistance of 1.00 inches w.g. at a rated flow of 125 Feet per Minute face velocity (500 CFM for a 24” x 24” X 5.875” Filter).
3.3 Each filter shall have a label showing the filter part number, test flow, resistance and filter efficiency.
That's what you want. The 99.997% are higher grade, but the 99.97 is fine. Be sure to use a good prefilter such as a super-allergen furnace filter and the HEPA will last a lifetime.
RR
--------------------
Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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So, Tri Dim just sent me a replacement hepa filter (the first had some tears in the fabric of the filter). Power to them. I barely asked for a replacement and was more curious about if there was any repair possibilties.
I still have a dilemma, though:
My original filter was rated at .91 wg at 500 CFM.
The one they sent me in replacement is .65 wg at 500 CFM.
I've got a pretty strong 4 speed blower that I'll put on low and choke it off, but I'm wondering if I can still achieve laminar flow.
I'm still a bit shocked that they replaced the filter.
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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Re: wow TriDim is reasonable [Re: shubrick]
#16554355 - 07/19/12 02:39 PM (9 months, 24 days ago) |
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Thank you everyone for your input and journals. RR and Evil shroom especially. I know that evilshroom made a lot of his notes off of other people's past work and so they get credit too.
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
Posts: 39,269
Loc: USA Mountain Northwest
Last seen: 2 days, 23 hours
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Re: wow TriDim is reasonable [Re: shubrick]
#16554695 - 07/19/12 03:59 PM (9 months, 24 days ago) |
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Looks about perfect. If the flame bends that same amount over the entire surface, you're golden.
RR
--------------------
Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
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shubrick
Registered: 06/11/10
Posts: 139
Last seen: 1 month, 24 days
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Re: wow TriDim is reasonable [Re: RogerRabbit]
#16555616 - 07/19/12 07:21 PM (9 months, 24 days ago) |
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You know I was afraid that it wouldn't be even, but I'll be damned, I'm golden.
Quote:
RogerRabbit said:
Looks about perfect. If the flame bends that same amount over the entire surface, you're golden.
RR
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