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 Tripping2Adventure
StealingKnowledge
 
Registered: 03/28/16
Posts: 371
Loc: Under a Rock, Bottom of t...
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 Uneven laminar flow. 
#25364874 - 08/03/18 05:08 PM (5 years, 8 months ago) |
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Hi everyone. Here's a link to my build
https://www.shroomery.org/forums/showflat.php/Number/24431448
I think I may have over done it with the two side by side filters. The math mad sense, but the unit itself didn't quite work out.
Around the edges of the two filters, I am getting very strong air flow, and in the middle of the filters i am getting barely any flow at all.
the plenum is 16" deep, 24" tall, and 48" long. the fan blows in through the center back of the plenum.
I had an idea that maybe if i blocked off one of the HEPA filters than i may have more even flow across the other?
Otherwise, I may have to take this thing apart and make some adjustments.... I just am not %100 sure what is causing the uneven flow. is it the separation of the flow where the two filters are butted up side by side? is it the size/shape of my plenum?
I also had an idea that if I sealed off the top 6" and bottom 6" of the filter i can get even flow across the middle.
Maybe when it comes down to it, I need to take this apart and build a single filter unit or buy a 24" x 48" hepa filter that doesn't have a separation in the middle. I'm not sure that the separation if the filter is the pure cause of the uneven flow though.
I'm done rambling. For those of you that can make sense of my rambling and throw some advice out, I'd love to hear it. Thanks all!!
front side
front side again
Back side
back side again
Front side, after back panel is sealed on.
and again
with prefilter in.
EDIT: Here's a visual
BLUE = High Flow
GREEN = Medium/Good Flow
RED = No Flow
Edited by Tripping2Adventure (08/03/18 05:24 PM)
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 Thesunbeam
Stranger
Registered: 07/08/18
Posts: 1,646
Last seen: 3 years, 1 month
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I would seal up the hole from the previous blower and put a blower behind each filter. Maybe have the blowers pointed to the center of the filters? It would require some serious design mods but it’s an idea. Why do you need such a big hood anyways?...I’m jealous!
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Thesunbeam
Stranger
Registered: 07/08/18
Posts: 1,646
Last seen: 3 years, 1 month
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Re: Uneven laminar flow. [Re: Thesunbeam]
#25364925 - 08/03/18 05:38 PM (5 years, 8 months ago) |
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Know what I’m saying though? Instead of above the filters have everything pointed in the same direction. Since you are experiencing low flow in the middle of have the blowers positioned in the middle of the filters .
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bodhisatta  
Smurf real estate agent
Registered: 04/30/13
Posts: 61,891
Loc: Milky way
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Re: Uneven laminar flow. [Re: Thesunbeam]
#25365521 - 08/03/18 11:08 PM (5 years, 8 months ago) |
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Are the filters used?
If not try a baffle in the plenum by the blower outlet first
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Tripping2Adventure
StealingKnowledge
Registered: 03/28/16
Posts: 371
Loc: Under a Rock, Bottom of t...
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Re: Uneven laminar flow. [Re: bodhisatta]
#25365733 - 08/04/18 04:08 AM (5 years, 8 months ago) |
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Brand new. Ones been sitting opened for 1 year and the other has been sealed in the box. A baffle?
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drake89
Mushroom Magnate
Registered: 06/26/11
Posts: 4,168
Loc: TN
Last seen: 5 years, 1 month
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Your fans is too small. That tiny thing probably develops no back pressure at all. You want at least a half HP fan and run it on low speed. Or get a 10 or 12" can fan
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bodhisatta
Smurf real estate agent
Registered: 04/30/13
Posts: 61,891
Loc: Milky way
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Re: Uneven laminar flow. [Re: drake89]
#25366308 - 08/04/18 11:37 AM (5 years, 8 months ago) |
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I think that's a 1tdu2 he has which is about 1/2 hp iirc.
But that fan won't run 2x4 feet of filter it will run 2x2 feet filter.
That blower does about 1000cfm at 1-1.2" resistance which sounds like enough for 800sqft but it's only 20% over so won't last the life of the filters
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Thesunbeam
Stranger
Registered: 07/08/18
Posts: 1,646
Last seen: 3 years, 1 month
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Re: Uneven laminar flow. [Re: bodhisatta]
#25366408 - 08/04/18 12:52 PM (5 years, 8 months ago) |
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You can get a furnace blower for about 30$ and it’s got A SHIT TON of power, more than enough for a 2x4 filter. Just look on Craig’s list
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bodhisatta
Smurf real estate agent
Registered: 04/30/13
Posts: 61,891
Loc: Milky way
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Re: Uneven laminar flow. [Re: Thesunbeam]
#25366418 - 08/04/18 12:55 PM (5 years, 8 months ago) |
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Not necessarily, the blower he already has is bigger than some central air blowers. and designed for higher resistance
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Quadman
Challenged
Registered: 04/23/16
Posts: 2,529
Loc: IL 
Last seen: 2 months, 6 days
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Re: Uneven laminar flow. [Re: bodhisatta]
#25366747 - 08/04/18 03:51 PM (5 years, 8 months ago) |
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Based on what Bodi says about your fan. It may be short on intake area .Try taking off the front that has the filter in it and then test. It won't hurt to run wide open without a filter for 15 or 20 minutes.
Fan won't produce cfms if it can't get enough air.
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Edited by Quadman (08/04/18 04:01 PM)
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Tripping2Adventure
StealingKnowledge
Registered: 03/28/16
Posts: 371
Loc: Under a Rock, Bottom of t...
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Re: Uneven laminar flow. [Re: Quadman]
#25366930 - 08/04/18 05:54 PM (5 years, 8 months ago) |
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Quote:
bodhisatta said:
I think that's a 1tdu2 he has which is about 1/2 hp iirc.
But that fan won't run 2x4 feet of filter it will run 2x2 feet filter.
That blower does about 1000cfm at 1-1.2" resistance which sounds like enough for 800sqft but it's only 20% over so won't last the life of the filters
Yes, 1tdu2 is correct. Quote:
Quadman said:
Based on what Bodi says about your fan. It may be short on intake area .Try taking off the front that has the filter in it and then test. It won't hurt to run wide open without a filter for 15 or 20 minutes.
Fan won't produce cfms if it can't get enough air.
Here are the flow rates without the prefilter. It does have flow across all the filters, but the CFM's are too high and it's still not even flow.
         
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NothingsChanged
Striving for Excellence
Registered: 05/28/11
Posts: 10,311
Loc: North/Western WA
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Opinion only.
The solid joint between filters is causing an eddie like if you put a stick in a stream. Something like this(Strickley an example obviously different context(?)).
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NothingsChanged
Striving for Excellence
Registered: 05/28/11
Posts: 10,311
Loc: North/Western WA
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Pulling air from the front above the discharge may also be affecting things in other ways?
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Quadman
Challenged
Registered: 04/23/16
Posts: 2,529
Loc: IL
Last seen: 2 months, 6 days
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I haven't checked mine with a meter. Would venture to say filters may not give perfectly even flow.
Do the numbers look better with the bigger intake? Flow rates will drop some with the pre filters.
With the discharge boxed in like you have. The air stream should be clean with those numbers?
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Rombino
Strange noobie jedi
Registered: 09/21/17
Posts: 324
Loc: The Id
Last seen: 1 year, 9 months
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Quote:
NothingsChanged said:
Opinion only.
The solid joint between filters is causing an eddie like if you put a stick in a stream. Something like this(Strickley an example obviously different context(?)).
I'm thinking this is partly why Bod suggested a baffle? To get the air pressure to hit each side more squarely....
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bodhisatta
Smurf real estate agent
Registered: 04/30/13
Posts: 61,891
Loc: Milky way
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Re: Uneven laminar flow. [Re: Rombino]
#25369436 - 08/06/18 05:03 AM (5 years, 8 months ago) |
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Mostly to eliminate any harmonic patterns in the air flow or eddies.
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Tripping2Adventure
StealingKnowledge
Registered: 03/28/16
Posts: 371
Loc: Under a Rock, Bottom of t...
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Re: Uneven laminar flow. [Re: bodhisatta]
#25370095 - 08/06/18 12:28 PM (5 years, 8 months ago) |
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Quote:
Quadman said:
Based on what Bodi says about your fan. It may be short on intake area .Try taking off the front that has the filter in it and then test. It won't hurt to run wide open without a filter for 15 or 20 minutes.
Fan won't produce cfms if it can't get enough air.
So i definitely did have the intake area of the blower chocked back in attempt to achieve lower CFMS. This gave me a small dead spot in the middle of the filters and good flow around the edges.
Opening the Intake area back up to less restriction (still prefiltered) gives me flow across the whole unit, which is what i need. The flow is a little higher around the edges, but the central area of the filters will most culture work will be done has the flow I need.
I'm using a few agar dishes to test any contamination issues with the machine... when testing is done I'll move into more culture work with it or take the Flow Hood unit back apart if need be.
If it comes to tearing it back apart, I'm first going to take Bodhisatta's advice
Quote:
bodhisatta said:
try a baffle in the plenum by the blower outlet first
If I have issues with being able to get even flow across still, I will just buy another 1tdu2 and build a wall between the two filters in the plenum.
Quote:
Thesunbeam said:
I would seal up the hole from the previous blower and put a blower behind each filter. Maybe have the blowers pointed to the center of the filters?
I appreciate everyone pitching in to help me figure this out. You have all helped tremendously.
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Quadman
Challenged
Registered: 04/23/16
Posts: 2,529
Loc: IL
Last seen: 2 months, 6 days
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Not perfect, but I think it should serve you fine.
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Thesunbeam
Stranger
Registered: 07/08/18
Posts: 1,646
Last seen: 3 years, 1 month
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Re: Uneven laminar flow. [Re: Quadman]
#25370641 - 08/06/18 05:16 PM (5 years, 8 months ago) |
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Damn that wall idea is pretty good...you showed us!
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Thesunbeam
Stranger
Registered: 07/08/18
Posts: 1,646
Last seen: 3 years, 1 month
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Re: Uneven laminar flow. [Re: Thesunbeam]
#25370649 - 08/06/18 05:19 PM (5 years, 8 months ago) |
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Hahahaha guess you’re thinking “inside the box” if you will 
Edited by Thesunbeam (08/06/18 05:20 PM)
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