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 Anno
Experimenter
Registered: 06/17/99
Posts: 24,010
Loc: my room
Last seen: 10 hours, 6 minutes
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Quote:
legallyhomeless said:
After I relied the last time, I read a post by RR that said its not good to have slanted glass because it interupts the laminar flow
If you have a laminar flow to start with, yes.
If you don't have laminar flow, which was the case in my construction, you have to make the opening for the air to escape so small, so you don't get a backflow of outside air tot he area. Very easy to test using a burning incense stick.
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The Rich Jerk
Grow Mushrooms from Spores - PF-Tek for Simple Minds
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FreeSporePrints
stronzo chilegge
Registered: 03/06/05
Posts: 878
Loc: Rome, ITALY
Last seen: 13 hours, 26 minutes
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 Re: Im finally building a flow hood [Re: Anno]
#8360372 - 05/04/08 04:13 AM (4 months, 17 hours ago) |
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Quote:
Anno said:
..you have to make the opening for the air to escape so small, so you don't get a backflow of outside air tot he area. Very easy to test using a burning incense stick.
opening for the air to escape so small, to don't get a backflow?
..what do you mean mate?
any pic is appreciated.
Thanks,
Fabio
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,010
Loc: my room
Last seen: 10 hours, 6 minutes
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This doesn't concern your flowhood, I was talking about closed, glove box type hoods.
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The Rich Jerk
Grow Mushrooms from Spores - PF-Tek for Simple Minds
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 FooMan
Registered: 02/02/05
Posts: 5,720
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Anno is saying to make the hole for the air to escape small enough that it ensures that all of the air is flowing out. If the hole(s) were too big, there wouldn't be enough positive pressure to ensure that there was no backflow of (possibly contaminated) air into the box.
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Thank you Shdwstr!  
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KaptKid
Spaced Pirate
Registered: 12/11/03
Posts: 4,678
Loc: Bright Side of the Sun
Last seen: 51 minutes, 8 seconds
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 Re: Im finally building a flow hood [Re: FooMan]
#8360546 - 05/04/08 07:01 AM (4 months, 15 hours ago) |
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I used a positive air flow glove box for 2 years with great results. Cheap to build to.
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Child of the 60's, Tripping ever since.
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legallyhomeless
mooch
Registered: 07/01/05
Posts: 2,076
Loc: UMA for the Refuge
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Re: Im finally building a flow hood [Re: KaptKid]
#8360563 - 05/04/08 07:19 AM (4 months, 14 hours ago) |
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I understand what you mean now Anno. I got some great links for filters, but what about blowers?
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B+ Grow Log
Manure: A Start to Finish Guide
My Favorite Read
If you have a Lipa Yai, Pink Buffalo, Golden Teacher, Malabar, Vietnamese, or Colorado print and want to trade, PM me.
For Sale: Flowhood blowers.
 
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FooMan
Registered: 02/02/05
Posts: 5,720
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I found one place that has OK prices:
http://www.electricmotorwarehouse.com/dayton_blower.htm
Ebay definitely has some deals, but many of the auctions don't have specs available for the air flow under various static pressures and the sellers are usually clueless too. Many of the manufacturer's websites don't include this information either, so it's hard to match a blower to the filter.
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Thank you Shdwstr!
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Digital Reality
Strangers in the dark
Registered: 05/01/07
Posts: 142
Last seen: 2 days, 8 hours
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Im building a flow hood right now and heres the supplies ive been looking at
Filter
http://www.filtera-b2b.com/businessfilters/hepa.htm#99.99wood
Blower
http://www.grainger.com/Grainger/wwg/start.shtml
and the part number to search for is 7f730
Blower
http://marylandhydroponics.com/squirrel-cage-fans.html
Blower
http://www.horticulturesource.com/product_info.php/cPath/43_32/products_id/1659?osCsid=c188ed2fb860681403f35070502388ae
Im just a little confused right now how big of a blower i need for a 18X24 hepa. Im kinda in the same boat as you. i feel a 12X24 will be to small and the 24X24 will be huge. lol i wanna do that slurry tek too. Shit looks awesome but would be a huge pain in the ass in a glove box.
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FooMan
Registered: 02/02/05
Posts: 5,720
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Quote:
Digital Reality said:
Im just a little confused right now how big of a blower i need for a 18X24 hepa. Im kinda in the same boat as you. i feel a 12X24 will be to small and the 24X24 will be huge. lol i wanna do that slurry tek too. Shit looks awesome but would be a huge pain in the ass in a glove box.
You need to know the static pressure of the filter and the air flow rate of the blower at that pressure. Anno has a good writeup here: http://www.fungifun.org/English/Flowhood
For an 18 x 24" filter, you would need a blower that blows around 300cfm at the sum static pressure of your filter + prefilter.
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Thank you Shdwstr!
Edited by FooMan (05/21/08 04:25 PM)
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legallyhomeless
mooch
Registered: 07/01/05
Posts: 2,076
Loc: UMA for the Refuge
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Re: Im finally building a flow hood [Re: FooMan]
#8430313 - 05/21/08 08:11 PM (3 months, 14 days ago) |
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Ive yet to build mine because I dont understand the chart thing still.
""For an 18 x 24" filter, you would need a blower that blows around 300cfm at the sum static pressure of your filter + prefilter. ""
This makes more sence to me but Im still a bit confused.
--------------------
B+ Grow Log
Manure: A Start to Finish Guide
My Favorite Read
If you have a Lipa Yai, Pink Buffalo, Golden Teacher, Malabar, Vietnamese, or Colorado print and want to trade, PM me.
For Sale: Flowhood blowers.
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 Brainiac
Ghost
Registered: 04/29/06
Posts: 8,395
Loc: I will know,when I'm ther...
Last seen: 1 minute, 2 seconds
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Quote:
legallyhomeless said:
Ive yet to build mine because I dont understand the chart thing still.
""For an 18 x 24" filter, you would need a blower that blows around 300cfm at the sum static pressure of your filter + prefilter. ""
This makes more sence to me but Im still a bit confused.
From FP web site Its says you need a blower that moves 1,040 CFM at .8" static pressure for a 18"x 5.5"x 24"...
Edited by Brainiac (05/21/08 08:56 PM)
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FooMan
Registered: 02/02/05
Posts: 5,720
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Re: Im finally building a flow hood [Re: Brainiac]
#8430829 - 05/21/08 10:06 PM (3 months, 13 days ago) |
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Quote:
Brainiac said:
Quote:
legallyhomeless said:
Ive yet to build mine because I dont understand the chart thing still.
""For an 18 x 24" filter, you would need a blower that blows around 300cfm at the sum static pressure of your filter + prefilter. ""
This makes more sence to me but Im still a bit confused.
From FP web site Its says you need a blower that moves 1,040 CFM at .8" static pressure for a 18"x 5.5"x 24"...
Where does it say that? I know their "universal" blower has those specs and can work with an 18x24, but it will also work for 24x24" and 24x36" sizes that require higher flow. For an 18x24 filter, you would need a speed controller with the blower to slow the air flow down. I know someone said that Stamets now recommends 150fpm for laminar flow, but even with the 50fpm increase over what TMC says, a 1,040cfm blower would still be overkill.
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Thank you Shdwstr!
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Brainiac
Ghost
Registered: 04/29/06
Posts: 8,395
Loc: I will know,when I'm ther...
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Re: Im finally building a flow hood [Re: FooMan]
#8431047 - 05/21/08 10:58 PM (3 months, 13 days ago) |
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With a good Pre-filter added to it ?
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I'm dyslexia, so get the fuck over it. "Ardet Nec Consumitur" (burned but not destroyed) People shouldn't be afraid of it's government.The government should be afraid of it's people..
Spores I need
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FooMan
Registered: 02/02/05
Posts: 5,720
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Re: Im finally building a flow hood [Re: Brainiac]
#8434183 - 05/22/08 07:02 PM (3 months, 13 days ago) |
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I'm no expert, but I don't think a prefilter should have much static pressure. It's just to help keep dust and larger particles out to give the blower and filter a longer lifespan.
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Thank you Shdwstr!
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Digital Reality
Strangers in the dark
Registered: 05/01/07
Posts: 142
Last seen: 2 days, 8 hours
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Yeah im still confused as well. One person says 300cfm and the other says something over 1000cfm. So I think what I might do is just get that blower from Grainger with a fan controller. The blowers is 200$ which sucks but its nice to have something to big with a controller so you can up the speed a little when the filters start to get old and clogged. It was a post I saw from RR and its def a good point. But more than anything that blower def would be able to push a bigger filter if I ever got a larger room and could build a larger hood. Anyway if you’re interested here’s a link to a cheap speed controller.
http://www.littlegreenhouse.com/accessory/controls2.shtml
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lipa
Registered: 07/24/07
Posts: 415
Last seen: 1 hour, 27 minutes
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Get something between500 and a 1000 cfm. Cfm has nothing to do with the static pressure your looking for. It has to do with the power of the fan. Look at the manufacturers details of each fan you are looking at.. The Cfm is the volume and the static pressure is the power. Without the power the CFM of the fan is useless. You want enough static pressure to support the cfm. Does that help any? Yes it is desirable to get a higher cfm fan and a speed control because as the efficiency of the filter goes up and there are more particles on the filter you will want to adjust the "cfm".
Get a blower with at least .8 static pressure. A cfm of about 750 is ideal and 1000-1200 is better in the long run when you want a larger unit. It is all about the power "pressure".
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Digital Reality
Strangers in the dark
Registered: 05/01/07
Posts: 142
Last seen: 2 days, 8 hours
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Re: Im finally building a flow hood [Re: lipa]
#8436409 - 05/23/08 10:32 AM (3 months, 12 days ago) |
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Ahhh i see. That does make sense. I mean I still don’t understand how to calculate everything but I guess it’s kinda like a regular window fan. I can blow crazy amounts of air but it’s not powerful enough to blow air through water but a blower would have the power to push it through which is.
I guess I was getting confused because the charts ive seen that take blowers with a high CFM and show the gradual decline capability to push CFM at higher static pressure ratings.
But in the same sense what your saying is just because a blower is rated at 1000 cfm doesn’t mean its going to have enough ass to actually push any of it through the filter. It actually has to be rated or made I guess to do such.
Either way the one i was looking at on the grainer site does have specs for different SP ratings so it suites its purpose, but def good to know. Thanks!
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lipa
Registered: 07/24/07
Posts: 415
Last seen: 1 hour, 27 minutes
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Your welcome. The laminar flow filter that you buy should come with a sheet stating what static pressure and cfm you should have also. If not call the manufacturer and ask. They have to keep that information handy by law if they are selling them to labs with efficiency ratings. I hope you can now look in the mushroom cultivator and use the equations with an understanding of how if works out.
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FooMan
Registered: 02/02/05
Posts: 5,720
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Re: Im finally building a flow hood [Re: lipa]
#8437578 - 05/23/08 05:12 PM (3 months, 12 days ago) |
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It's the cfm of the blower @ the static pressure of the filter that counts. Blowers don't have a static pressure per se. They blow a given volume of air that drops as the static pressure increases. Usually the advertised air flow of a blower is the "free flow" cfm (0" static pressure or no filter).
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Thank you Shdwstr!
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FooMan
Registered: 02/02/05
Posts: 5,720
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Quote:
Digital Reality said:
Yeah im still confused as well. One person says 300cfm and the other says something over 1000cfm.
Well, what I said was based on the actual math involved in matching a blower to the size filter you were talking about (based on the Fungifun formula), the other post was a copied and pasted description of a blower on the FP site that works with 3 different size filters, 2 of which are quite a bit larger than what you asked for.
Not that the bigger blower is a bad idea though. Like you said, you can always set it up with a bigger filter down the road.
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Thank you Shdwstr!
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