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 PprPlns
Stranger
Registered: 07/30/08
Posts: 145
Last seen: 12 years, 20 days
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 Is this the right kind of HEPA? 
#11726744 - 12/27/09 02:50 PM (14 years, 3 months ago) |
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Damion5050
Mush Doctor
 
Registered: 05/01/08
Posts: 12,493
Loc: Lost In Translation ! 
Last seen: 3 years, 2 months
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Re: Is this the right kind of HEPA? [Re: PprPlns]
#11728916 - 12/27/09 10:18 PM (14 years, 3 months ago) |
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 CheeWiz
Registered: 09/28/08
Posts: 276
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Re: Is this the right kind of HEPA? [Re: PprPlns]
#11728925 - 12/27/09 10:19 PM (14 years, 3 months ago) |
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Hi; Yes that one will work and is a good choice for someone starting out. You can find a number of posts here on how to build the box and I would recommend the double box design. That is a box built for the filter and bower with another box built to fit over the filter/bower box to hold a prefilter that's aligned with dow pins and held in place thumb clips. The flow can be adjusted by looking at the smoke from a burning punk and adjusting a piece of paper over the prefilter when the unit is turned on. Go to RR site or watch his video for more details. I hope this is of some help; Hipster
Edited by CheeWiz (12/28/09 07:18 AM)
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PprPlns
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Last seen: 12 years, 20 days
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Re: Is this the right kind of HEPA? [Re: CheeWiz]
#11731063 - 12/28/09 11:24 AM (14 years, 3 months ago) |
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Thank you. What are the distinguishing traits of a laminar flow hepa vs normal hepa? Is it just the thickness?
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Damion5050
Mush Doctor
Registered: 05/01/08
Posts: 12,493
Loc: Lost In Translation !
Last seen: 3 years, 2 months
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Re: Is this the right kind of HEPA? [Re: PprPlns]
#11731077 - 12/28/09 11:27 AM (14 years, 3 months ago) |
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Key word LAMINAR FLOW
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
Posts: 42,214
Loc: Seattle
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Re: Is this the right kind of HEPA? [Re: Damion5050]
#11731120 - 12/28/09 11:34 AM (14 years, 3 months ago) |
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You want a filter with a higher resistance. By creating resistance, static pressure develops on the back side. When you have a constant static pressure on the back side of a filter, air flows more evenly out the front. When you look at performance data for a filter, find one that was tested at .8" wc to 1.1" wc. The low resistance, high flow filters are great for clean rooms such as labs, data centers, etc., but they're not likely to develop laminar flow. We want ideally a high resistance, low flow filter for bench work.
RR
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Thomas Edison
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Grzyby
Janitor w/light cooking duties
Registered: 03/24/09
Posts: 900
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Re: Is this the right kind of HEPA? [Re: RogerRabbit]
#11731213 - 12/28/09 11:54 AM (14 years, 3 months ago) |
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WHat's the best size , 24 x 12 x 5.8 or 24 x 18 x 5.8 ?? WHat should i expect to pay for these? I am considering buying it from FP, they are $129 and $159 there and i know it will be the correct one. Every where i look they seem to be about this price. Is it possible to find cheaper?
Thanks
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PprPlns
Stranger
Registered: 07/30/08
Posts: 145
Last seen: 12 years, 20 days
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Re: Is this the right kind of HEPA? [Re: Grzyby]
#11731260 - 12/28/09 12:05 PM (14 years, 3 months ago) |
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I found their performance numbers but I don't know how to interpret it.It has a resistance of .8 at 1250 cfm.
http://www.purolatorair.com/brochures/P-ULTRACELL.pdf
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RogerRabbit
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Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 1 month
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Re: Is this the right kind of HEPA? [Re: PprPlns]
#11731309 - 12/28/09 12:13 PM (14 years, 3 months ago) |
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As for size, bigger is always better. My flowhood is too small, and I'm also looking to expand to a bigger model.
To the OP, you might want to email them with your questions about laminar flow. For the filters I buy, I want about 100 to 150 fpm(feet per minute) of airspeed leaving the filter. That means for a 4 square foot filter, you'd want 400 to 600 cfm(cubic feet per minute) @ 1" of static pressure. If the filter you're looking at achieves a greater flow at 1" of static pressure(WC), then it's probably not the best choice. There's fudge room on either side, but don't get a filter that flows 100 feet per minute at only .4" of static pressure. The chances are very good with such a filter that it would blow stronger in the middle than around the edges, creating eddies.
RR
--------------------
Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
"I've never had a failed experiment. I've only discovered 10,000 methods which do not work."
Thomas Edison
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PprPlns
Stranger
Registered: 07/30/08
Posts: 145
Last seen: 12 years, 20 days
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Re: Is this the right kind of HEPA? [Re: RogerRabbit]
#11731493 - 12/28/09 12:54 PM (14 years, 3 months ago) |
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Ok. While we're on the subject of flowhoods, what's the point of an induction motor? I searched posts but there's no definite answer. The only thing I saw was a single comment about noise.
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fastfred
Old Hand
Registered: 05/17/04
Posts: 6,899
Loc: Dark side of the moon
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Re: Is this the right kind of HEPA? [Re: PprPlns]
#11785062 - 01/07/10 05:18 PM (14 years, 3 months ago) |
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Most commercial flow hoods used in labs are not laminar flow. You don't need laminar flow and IMHO people have wasted a lot of money trying to get something they don't need.
For some reason a lot of mycology hoods like to use an open design and laminar flow. I've never figured out why they waste the extra expense.
For a non-laminar flow hood all you have to do is restrict the area that's open for your hands to access. If you want to just work directly in front of a big filter you'll need laminar flow. But most designs use non-laminar flow and a fume hood type design.
For those air comes in the top of a box and exits the handling area at the bottom.
Standard commercial non-laminar flow hood
 
Homemade flow hood...
-FF
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