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skarekrow101
Stranger
Registered: 12/07/13
Posts: 5
Last seen: 9 years, 11 months
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Please grade my hood calculations
#19273249 - 12/14/13 01:58 AM (10 years, 1 month ago) |
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Okay guys just wanting to verify my calculations are correct before i drop some $$ on building a hood. There's a lot of info. I've read on here and I'm hoping I'm comprehending it correctly. If I've made any miscalculations please let me know.
I'm going with a 24 x 24 x 5.8" filter from fungi.com ( http://www.fungi.com/product-detail/product/24-x-24-x-58-micron-filter.html ). Everyone seems to say they have the best filters, even though they are more expensive than ebay and such; I should also go with aluminum spacers (If there would be other suitable alternatives I'm open for suggestions, but I don't want a junk filter).
Next, I believe I should get a blower with at least 480 cfm (taking into account the extra 20% I've read that I should go above on the blower's cfm). I hope my math is right on this (Filter is 2x2; 2*2=4; 4*100=400 cfm; 400*20%=480 cfm blower)
Lastly on the build, my plenum should be roughly 2-2.5 times the thickness of the filter, so on a 5.8" filter the plenum should be roughly 14.5" (5.8 * 2.5 = 14.5" plenum, not including the filter width). If I include the filter width, the depth of my hood should be roughly 20" or so correct?
I've seen some awesome builds on here and I've read many posts so I'm hoping I've taken it all in correctly. Thanks for your input
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RogerRabbit
Bans for Pleasure



Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 11 months, 4 days
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Re: Please grade my hood calculations [Re: skarekrow101]
#19273933 - 12/14/13 09:49 AM (10 years, 1 month ago) |
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A good rule of thumb is to make the plenum as thick as the filter. The reason is thicker filters have less resistance, so need a larger plenum to moderate the turbulence from the blower. Since your thinner blower has higher resistance, the plenum can be smaller if you want. A 6" to 10" plenum will be fine, giving you more work space on your table.
I'd go with 500 to 600 cfm at or above the resistance rating on the filter, and then use a motor speed controller. You can run it a bit faster during the 1 hour before sterile work begins to scrub the air. Then, when you're suited up and ready to work, slow it down so the sterile airflow bends a cigarette lighter flame over 45 to 60 degrees when held in the work area, but doesn't make it flicker or try to blow out. 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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