Home Laboratory: DIY Fume Hood
- Thread starter dnBQByvHb8Zkawbjpx
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- diy fume hood ventilation
It's time to move on with the build:
- Cut out a large window into the box through which you will perform tasks inside the finished fume hood. It does not need to reach all the way to the bottom.
- Cut out a hole for the exhaust in the opposite side, situated closer to the top so that rising fumes can be extracted.
- Cut transparent plastic foil (it needs to have some thickness, cling film is insufficient) to fully cover the working window from side to side, but leaves the bottom 10-15 cm uncovered, and use adhesive tape to fix it to the fume hood on three sides (not the bottom).
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Meanwhile I've also built this contraption as a side quest before I finish the primary exhaust. The paper tube was cut crosswise about 12 cm deep from one end. The resulting segments were bent to fit a 12V computer fan and the pipe has essentially become a converter from round to square cross section. The fan was hot-glued into place and the gaps were sealed with adhesive tape. It is fugly as hell but it kind of works, however the fan is too weak and does not provide the expected air flow. I am unlikely to use it for the fume hood but it will do its job to extract fumes when doing soldering work on some electronics, for instance.
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I'm thinking you are not going to make your recommended 100ft/minute air speedyou would, of course, need 100 cfm to achieve 100 fpm in a 1'x1' opening. Just thought I would toss that out there when you are window shopping and day dreaming about fume hoods, that's what you are trying to shoot for. Less and an energetic reaction will exceed the capabilities of the hood. That's just what was beamed into my head. Don't take my word for it🫨
In this build I'll use a fan that moves 1730 cfm, that should be plenty even accounted for losses. I'll post the result in few days.
Told you that the cheapest solution is 50 euro (yeah now its 60 or so) 500 m3h 150mm fi PP made vent.
it has another plus. so its 2 birds one stone,, you can multiply them like 2-3 pieces so you have exhaust in many places then you can connect them into 3 pipes splitter (dont know the name) and it can be sucked by pressure vent that puts this air into filter (no loses from any vent)
it has another plus. so its 2 birds one stone,, you can multiply them like 2-3 pieces so you have exhaust in many places then you can connect them into 3 pipes splitter (dont know the name) and it can be sucked by pressure vent that puts this air into filter (no loses from any vent)
I'll get to that point later. Until then I'll finish this improvised build using things I already have and learn from experience what I really need to get and improve.
This. This is the exact opposite of a fume hood. This is a laminar flow cabinet . It blows air OUT of that 24x24x11.5 Neuclear certified HEPA filter. Under the top housing is...a squirrel cage blower out of a furnace. A fume hood protects you from the chemicals, but this protects the stuff from you mushrooms, but plants are often cloned in front of one and pharmacists and microbiologist use them . The 99.997% percent efficiency of the filter blows air at way faster than laminar speeds, to displace atmospheric air that could be contaminated with mold or bacterial spores. This thing served me well for 10 years practically 100% success. After 10 years, I sold it for the $200 I built it for. Laminar is just a catchy phrase, laminar flow in atmospheric air is a fairytale. , not to mention laminar flow is not a thing, it's a measurement and the unit of measurement is called the Reynolds number.
- By Dr. MMX
how often replacement of filters?
i suppose you just have cabinet inside and push air out yeah?
i suppose you just have cabinet inside and push air out yeah?
never, if at all possible. You need a prefilter, which is built into my housing for the blower, believe its a merv 8 or 9. It collects the large particleas and the hepa only has to handle the small particles. Tat 99.997% rating is at 3 microns, but it works better than that at 2 and 4 microns and below and above. The rason they use 3 microns is because that is the toughest point, where the way the filter operates changes from defraction to impaction. It's recommended that you push 100ft./min from the face. 100 ft x4 (because the filter is 2x2, 4 sq.ft) is 400cfm, but that needs to be at the resistance your filter has. They make 4" thick and 6" think hepa filters which have high resistance, 1" of mercury or more, but this one, being 12" thick has a resistance of .5" mmhg The squirrel cage blower has a capacity of 1600+cfm, So considering the resistance of the prefiter and filter it had an air speed of nearly 400 ft./min. Thedirtier the filter gets, the better it works, up until you just can't push enough air through it to overcome your breathe or a slight breeze, or moving your arms. If it ever got that clogged, I would unhook the start/run capacitor and plug it in and spin it backwards. Then it would suck all the shit right back out of the filter and blow it out the top and that's that, refurbished filter. Inside of this 2ft. x 2 ft. x 12" thick filter, the actual fiberglass filter material is 235 ft long or something like that, folded into pleats like an accordian.
It took 1 1/4 sheets of plywood, 2 b 8 ft. 2x4s a tube of liquid nails, a box of screws and basically 4 linear feet of machine cloth (which is the wire covering the filters). I spent a couople of months watching for a good filter on ebay. Someone who had a couple dozen. They need to be stunningly blemish free. If there is a tear in the filter or a dent in it, it's garbage, so don't buy one from someone who has 1 or2, they've likely been kicked around the shop for a year and have dents and stuff. You want one straight off the pallet.
I built this for $200, but to buy one like it starts at about $1500 and goes up from there
Yes it's just a cubical box with a hole in the top where the blower is sdcrewed, there are cleats inside at 12" that hold the hepa filter (the cleats are solid on all 4 sides and have weatherstripping, to make a good seal) the bezels on the front of the filters is made out of a ripped down 2x4 ripped to 1/2" thick
It took 1 1/4 sheets of plywood, 2 b 8 ft. 2x4s a tube of liquid nails, a box of screws and basically 4 linear feet of machine cloth (which is the wire covering the filters). I spent a couople of months watching for a good filter on ebay. Someone who had a couple dozen. They need to be stunningly blemish free. If there is a tear in the filter or a dent in it, it's garbage, so don't buy one from someone who has 1 or2, they've likely been kicked around the shop for a year and have dents and stuff. You want one straight off the pallet.
I built this for $200, but to buy one like it starts at about $1500 and goes up from there
Yes it's just a cubical box with a hole in the top where the blower is sdcrewed, there are cleats inside at 12" that hold the hepa filter (the cleats are solid on all 4 sides and have weatherstripping, to make a good seal) the bezels on the front of the filters is made out of a ripped down 2x4 ripped to 1/2" thick
I think a better option instead of using a cardboard box and some hot glue, would be a a small grow box with an akf + extremely oversized ventilation. And I suggest to blow out the air of the outlet out of the window.
If you working in the tent, of course you'll need normal protection gear (A2B2E2K2-HG-P3 filter mask !!).
But instead of buying a real fume hood, this would be the option I'd use.
If you working in the tent, of course you'll need normal protection gear (A2B2E2K2-HG-P3 filter mask !!).
But instead of buying a real fume hood, this would be the option I'd use.