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 Supalemonhaze
Spore syringe hater.
Registered: 10/02/15
Posts: 6,725
Loc: 12" down Europe's butthole
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 Re: Laminar Flow Hood Calculations  [Re: blindingleaf]
#23079337 - 04/03/16 02:30 PM (8 years, 14 days ago) |
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That's some nice wood leaf. I used scraps from my garage  some got resin stains on them. Ugly as fuck but hey, at least it works just as good. 
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blindingleaf
blue collar underworld
Registered: 07/19/13
Posts: 22,008
Loc: sub-surface unseen
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Thanks dude! I worked my ass off for that hood last summer cause I wantwanted it to b last one I ever build so i did it up. The back peice is scrap wood.
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A few thoughts on cultivation
MICROBIAL HUSBANDRY!!!!
The whole is greater than the sum of its parts
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Stargate
Addicted To Growing
Registered: 05/26/14
Posts: 1,124
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Re: Laminar Flow Hood Calculations [Re: blindingleaf]
#23081435 - 04/04/16 05:36 AM (8 years, 13 days ago) |
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Quote:
Supalemonhaze said:
Mine ain't like that so I dunno how that type is supposed to look. If you have enough space for your blower in that top box, it's good I reckon.
Well, that's a 3D model I made so that I can more easily convey my ideas. It should fit the blower perfectly. Good to know that it should be a workable setup.[
Quote:
blindingleaf said:
yea, that will work. i would get rid of that work area outshoot. keep those filter stops instead of using silicone to adhere the filter. the frame will push up against the weather proofing and hold the HEPA in place without air escaping unnecessarily.
Thanks for the tip about the filter stops. But I'm wondering, why take off the work area outshoot? You don't think a 1.2 inch drop below the laminar flow will matter?
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From before I started growing gourmet mushrooms:
  
Edited by Stargate (04/04/16 05:36 AM)
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blindingleaf
blue collar underworld
Registered: 07/19/13
Posts: 22,008
Loc: sub-surface unseen
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Re: Laminar Flow Hood Calculations [Re: Stargate]
#23081488 - 04/04/16 06:28 AM (8 years, 13 days ago) |
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i think u should be fine. i do elevate my plates now with the larger hood, but with the old one i would pour right onto the table.
the main reason I suggest omitting it is because it will be a PITA to move like that. so if u want to keep it, just don't attach it to the hood itself
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A few thoughts on cultivation
MICROBIAL HUSBANDRY!!!!
The whole is greater than the sum of its parts
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 Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: mushpunx]
#23082064 - 04/04/16 11:10 AM (8 years, 13 days ago) |
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Quote:
mushpunx said:
Yea I love flow hoods hehe.
You really shouldn't have bought the 12" deep filter. I know its cheaper than the 6" deep filters, and they *will* work for laminar flow but they are so bulky and heavy.
we seem to be confusing opinion with fact.
ANY HEPA will generate laminar flow.
each sq in of filter media will flow a certain cfm at a given pressure. greater area of 12" unit means more flow at less pressure, a cheaper blower, catching more crap before replacement.
Edited by Jack Why (04/04/16 11:40 AM)
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Jack Why
Stranger
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Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: mushpunx]
#23082302 - 04/04/16 12:29 PM (8 years, 13 days ago) |
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Quote:
mushpunx said:
Your filter is 24 x 24". 24 x 24 =576 576/144 = 4 x 100 = 400.
Your hood will need a blower that pushes at or around 400CFM @ a static pressure of 1.2 (.2 added for the pre filter).
the first step in any design project is to properly and precisely define your performance target metrics.
look at the fh as a tunnel with
a prefilter on one end
then blower
then hepa
then the boundry between your virgin air and smegma dripping hell...the outflow of fh.
you want 100 fpm not at the filter face but at the opening.
that's one reason you won't see a fh in a pharm lab w/o a hood. a design with a box for workspace helps prevent contam of the filter as well as allowing cutting blower req to a fraction and lowering air velocity over your work.
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
Edited by Jack Why (04/04/16 03:32 PM)
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mushpunx
Fungus Punk
Registered: 04/20/14
Posts: 13,394
Last seen: 2 months, 7 days
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Re: Laminar Flow Hood Calculations [Re: blindingleaf]
#23082649 - 04/04/16 02:08 PM (8 years, 13 days ago) |
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Quote:
blindingleaf said:
yea, that will work. i would get rid of that work area outshoot. keep those filter stops instead of using silicone to adhere the filter. the frame will push up against the weather proofing and hold the HEPA in place without air escaping unnecessarily
 
I agree with Blinding leaf!
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Amateur Mycologists United
AMU Q&A
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mushpunx
Fungus Punk
Registered: 04/20/14
Posts: 13,394
Last seen: 2 months, 7 days
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Re: Laminar Flow Hood Calculations [Re: Jack Why]
#23082685 - 04/04/16 02:23 PM (8 years, 13 days ago) |
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Quote:
Jack Why said:
Quote:
mushpunx said:
Yea I love flow hoods hehe.
You really shouldn't have bought the 12" deep filter. I know its cheaper than the 6" deep filters, and they *will* work for laminar flow but they are so bulky and heavy.
we seem to be confusing opinion with fact.
ANY HEPA will generate laminar flow.
each sq in of filter media will flow a certain cfm at a given pressure. greater area of 12" unit means more flow at less pressure, a cheaper blower, catching more crap before replacement.
Like I said.. I even put it between two asterixes.... a 12" filter *will* work for laminar flow... nothing to debate there.
A bigger, heavier filter and the larger plenum required behind it makes for a bulkier, heavier hood than a hood with the same size filter face built with a 6" deep filter. This is fact 
That he shouldn't have bought a 12" deep filter because of that... thats my opinion.
I dont see how the two are being confused at all dude
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Amateur Mycologists United
AMU Q&A
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: mushpunx]
#23082813 - 04/04/16 03:04 PM (8 years, 13 days ago) |
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kool
"You really shouldn't have bought the 12" deep filter"
didn't read like opinion...just sayin'.
since he isn't concerned with size can you see how this filter is perfect FOR HIM?
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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blindingleaf
blue collar underworld
Registered: 07/19/13
Posts: 22,008
Loc: sub-surface unseen
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Re: Laminar Flow Hood Calculations [Re: Jack Why]
#23082895 - 04/04/16 03:25 PM (8 years, 13 days ago) |
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Chill dude. Lets not have another thread devolve into semantic blockage
--------------------
A few thoughts on cultivation
MICROBIAL HUSBANDRY!!!!
The whole is greater than the sum of its parts
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mushpunx
Fungus Punk
Registered: 04/20/14
Posts: 13,394
Last seen: 2 months, 7 days
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Re: Laminar Flow Hood Calculations [Re: blindingleaf]
#23083212 - 04/04/16 04:39 PM (8 years, 13 days ago) |
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Quote:
blindingleaf said:
i think u should be fine. i do elevate my plates now with the larger hood, but with the old one i would pour right onto the table.
the main reason I suggest omitting it is because it will be a PITA to move like that. so if u want to keep it, just don't attach it to the hood itself
I use a baking rack when I do transfers and innoculations but since I put a sheet of glass down on my table Ive started pouring down to the table and I haven't had any problems yet
I think it was you Leaf that sugguested giving a cardboard hood a try before actually building one out of wood/plexiglass
I think that would be good advice here too. Try one made of cardboard see if he can move around comfortably and if he likes it build a detachable hood
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Amateur Mycologists United
AMU Q&A
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: Stargate]
#23083497 - 04/04/16 05:41 PM (8 years, 13 days ago) |
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I would definitely have a covered ws. every commercial fh I've ever seen has this feature. that's the hood. I designed 1 lam station w/o hood it was installed in a class 10 cleanroom for a particularly sensitive silicon process.
the first step in any design project is to properly and precisely define your performance target metrics.
look at the fh as a tunnel with
a prefilter on one end
then blower
then hepa
then the boundry between your virgin air and smegma dripping hell...the outflow of fh.
you want 100 fpm not at the filter face but at the opening.
that's one reason you won't see a fh in a pharm lab w/o a hood. a design with a box for workspace helps prevent contam of the filter as well as allowing cutting blower requirements to a fraction and lowering air velocity over your work. cover the top half of the opening w/ plexi cuts you flow requirement in half. ergo better and cheaper.
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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Stargate
Addicted To Growing
Registered: 05/26/14
Posts: 1,124
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Re: Laminar Flow Hood Calculations [Re: Jack Why]
#23084719 - 04/05/16 12:38 AM (8 years, 13 days ago) |
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Building it out of cardboard the first time sounds like a great idea! Conveniently, I've got a ton of boxes right now due to moving into a new house. I'm going to be using the garage in this house to grow oyster mushrooms. Because of this, I'm thinking of using the fh for both laminar flow, as well as to actually keep the air clean. I'll have to use a variable speed controller for that, or what ever they are called in this situation.
Jack Why, about that hood. Does it need to shoot strait out from the HEPA, or can I taper it a bit outward to make my work space larger?
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From before I started growing gourmet mushrooms:
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Supalemonhaze
Spore syringe hater.
Registered: 10/02/15
Posts: 6,725
Loc: 12" down Europe's butthole
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Re: Laminar Flow Hood Calculations [Re: Stargate]
#23084844 - 04/05/16 02:12 AM (8 years, 12 days ago) |
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Tapering the enclosure won't give you airflow at the extra space you created. Laminar flow is a body of air that moves straight so unless the air is redirected it will keep going straight, no matter how much extra space there is on the sides.
That said an enclosure is not necessary for our purposes. But yes I agree with jack that an enclosure is extra protection for the sterility of the air and laminar flow as well as the fact that it can be run at lower fpm safely. Some commercial hoods have a low option that operates at 60fpm, this would probably not be possible without an enclosure.
But IMO an enclosure will restrict your movements to a box the size of your filter. A hood is comfortable because unlike a SAB, you are nothing but restricted. An enclosure changes this.
If I were to build and enclosure for the advantages mentioned above, I would only make it a few inches out, maybe 6-10" so I can still put stuff on the table outside of the flow without having to pull my hands back out of the enclosure. You need things like your alcohol bottle and torch to be easily reached but I prefer to leave them outside the flow, an enclosure would make this difficult.
I was going to build it to be honest. Was gonna have it made of thick see through plastic sheets but by the time I was going to order them, I realised that I will be restricted and that it is not necessary as I was already having wonderful results with it like it was.
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: Stargate]
#23085443 - 04/05/16 09:33 AM (8 years, 12 days ago) |
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cardboard is a great idea. variable speed and any affordable adjustability goes into all my designs. laminar air can live with 10 degree taper at this speed, no quick changes in cross section. the only place really critical is at the hole that you work through. a sealed box needs no air flow to keep "dust" out. when we put a hole in the box, we need to pressurize the box, making it "uphill" for room air to get into our box. smaller hole =slower air across work= smaller blower = <$$. the flow before this point is totally irrelevant. the air flows out because it's a downhill slide to a lower energy level. vortices or turbulence can give "dust" a higher energy level and a nonzero probability of crossing this barrier, here laminar is good, elsewhere not as much. bottom line... at 100fpm even salmon-ella can't swim upstream. get some smokesticks (cigarettes) they can show u air flow patterns. go spearmint and have fun.
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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mushpunx
Fungus Punk
Registered: 04/20/14
Posts: 13,394
Last seen: 2 months, 7 days
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Re: Laminar Flow Hood Calculations [Re: Jack Why]
#23085525 - 04/05/16 10:03 AM (8 years, 12 days ago) |
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I like using incense sticks to show air flow, that and a flame test
Jack - are you an engineer? You design flow benchs
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Amateur Mycologists United
AMU Q&A
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Tapering the enclosure won't give you airflow at the extra space you created.
ya know how boyle's law says when pressure drops, the molecules spread out? the cross section increases, pressure drops,it's like boyle's molecules except the flow lines spread. the books say 7-10 deg no prob.
Laminar flow is a body of air that moves straight so unless the air is redirected it will keep going straight, no matter how much extra space there is on the sides.
not quite or airplanes couldn't fly. a wing cuts air into 2 chunks, 1 under the wing has a shorter curve. assuming both surfaces are going about the same speed, both chunks have to arrive at the trailing edge together, the air has to flow faster across the upper curve. bernouli does the rest. when flow isn't smooth it stalls and falls. laminar means flow lines are basically parallel.
But IMO an enclosure will restrict your movements to a box the size of your filter.
this is counterintuitive but wrap your head around this design: build an airtight box the size of texas ( i'll wait). cut 2 holes, 1 for 1sq ft filter in dallas,1 for 1/2 sq ft access in austin. blow 50 fpm thru filter bring the box up to pressure before opening access hole...this will take a minute. open access you have 100fpm (we're ignoring weather conditions in the box).
exhaust V = filter area*V/exhaust area...this is the key to allowing a small blower.
the box can be any size, by making the access as small as possible vel across work is reduced
laminar flow is not the holy grail.
it's a pressure thing
I prefer to leave them outside the flow, an enclosure would make this difficult.
why that? I wasn't planning that.
thanx
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
Edited by Jack Why (04/24/16 06:37 PM)
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: mushpunx]
#23086170 - 04/05/16 01:50 PM (8 years, 12 days ago) |
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Quote:
mushpunx said:
I like using incense sticks to show air flow, that and a flame test
Jack - are you an engineer? You design flow benchs
better yet, keeps your hand out of the flow.
yes,40+ years ago I started designing machines i'm addicted. my last couple jobs were designing custom automated industrial stuff. whatever they wanted I designed.
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: blindingleaf]
#23087645 - 04/05/16 07:36 PM (8 years, 12 days ago) |
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Quote:
blindingleaf said:
Chill dude. Lets not have another thread devolve into semantic blockage
in reference to what exactly?
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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Jack Why
Stranger
Registered: 06/24/12
Posts: 34
Last seen: 7 years, 11 months
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Re: Laminar Flow Hood Calculations [Re: mushpunx]
#23143620 - 04/22/16 08:34 AM (7 years, 11 months ago) |
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Quote:
mushpunx said:
I like using incense sticks to show air flow, that and a flame test
Jack - are you an engineer? You design flow benchs
yes I've designed hoods ,cleanrooms, etc, etc professionally.
there is NO relationship b/t filter thickness and plenum volume.
there is NO minimum static pressure required for laminar flow.
.000001 in h2o static pressure will give laminar flow out of ANY HEPA.
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until u know why, you don't know jack.
Grant me the strength to change the things i can,
the serenity to endure those i can not,
and the wisdom to hide well the bodies
of those who try to tell me the difference.
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