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My wife Jennifer makes cast-resin jewelry1. She uses a polyester resin, which works a lot like fiberglass resin (mix the resin with a hardener/catalyst, pour), but unfortunately it smells about as bad too. Because of the toxic fumes, good ventilation is a must. In the summer months, it's no problem to do the casting outside, but doing it outdoors in the Canadian winter is not really an option. We needed some sort of indoor ventilation system to protect her from the fumes (like some sort of fume hood or something!).
What emerged is a fume hood based around a range hood, with a sealed wooden enclosure and a clear plastic window that forms a fixed sash. It is built on a cart, making the whole setup portable; all that's needed is an electrical outlet and somewhere to vent the fumes. In practice however, it's essentially a fixed installation that we can move out of the way if necessary.
I guess I should do the disclaimer thing and point out a few things. This was a quick-and-dirty design and build -- we were basically interested in moving the stink outside, not setting up a chemistry lab. This hood is NOT meant for chemical storage or use with highly flammable or explosive substances (do your homework on the chemicals you're using before building one of these). Also, this project involves basic wiring of a 120V circuit as well as various sharp and pointy tools. Builder discretion is advised.
1<plug> Check out more of her work at her ETSY page. </plug>
What emerged is a fume hood based around a range hood, with a sealed wooden enclosure and a clear plastic window that forms a fixed sash. It is built on a cart, making the whole setup portable; all that's needed is an electrical outlet and somewhere to vent the fumes. In practice however, it's essentially a fixed installation that we can move out of the way if necessary.
I guess I should do the disclaimer thing and point out a few things. This was a quick-and-dirty design and build -- we were basically interested in moving the stink outside, not setting up a chemistry lab. This hood is NOT meant for chemical storage or use with highly flammable or explosive substances (do your homework on the chemicals you're using before building one of these). Also, this project involves basic wiring of a 120V circuit as well as various sharp and pointy tools. Builder discretion is advised.
1<plug> Check out more of her work at her ETSY page. </plug>
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Signing UpStep 1Design and sizing
I found more info than I needed on fume hood design here. The first image below is also from that page.
The key piece of information needed is the face velocity, the speed at which air is sucked through the open face of the hood. According to the link above (and others) 60 - 100 ft/min is good for most applications. I chose 100 ft/min as the design point and made a guess of 2 ft2 for the opening, which would mean that I need a fan capable of 100 ft / min * 2 ft2 = 200 ft3 / min (cfm).
I started looking around for exhaust fans, thinking I would build it around a bathroom fan. The obvious choice of a range hood didn't occur to me until it popped up in my searches. It turns out a range hood suits the project nicely since it has an appropriate-sized fan, a light, and a shroud already built-in. I found a used-but-new range hood on a local classifieds website that has a 180 cfm fan and 30" shroud.
Without changing the face velocity, 180 cfm means the opening can only be 1.8 ft2. The front of the hood tapers inward, ending at about 2 ft at the front. Leaving the entire width open means that the height of the opening should be no more than 1.8 ft2 / 2 ft = 0.9 ft * 12 in / ft = 10.8 inches. I'm a fan of round, conservative numbers so I went with 10". Don't forget to mock it up again at that height to make sure the opening would be big enough to work through comfortably. Once you're satisfied with the geometry it's time to get building.
The key piece of information needed is the face velocity, the speed at which air is sucked through the open face of the hood. According to the link above (and others) 60 - 100 ft/min is good for most applications. I chose 100 ft/min as the design point and made a guess of 2 ft2 for the opening, which would mean that I need a fan capable of 100 ft / min * 2 ft2 = 200 ft3 / min (cfm).
I started looking around for exhaust fans, thinking I would build it around a bathroom fan. The obvious choice of a range hood didn't occur to me until it popped up in my searches. It turns out a range hood suits the project nicely since it has an appropriate-sized fan, a light, and a shroud already built-in. I found a used-but-new range hood on a local classifieds website that has a 180 cfm fan and 30" shroud.
Without changing the face velocity, 180 cfm means the opening can only be 1.8 ft2. The front of the hood tapers inward, ending at about 2 ft at the front. Leaving the entire width open means that the height of the opening should be no more than 1.8 ft2 / 2 ft = 0.9 ft * 12 in / ft = 10.8 inches. I'm a fan of round, conservative numbers so I went with 10". Don't forget to mock it up again at that height to make sure the opening would be big enough to work through comfortably. Once you're satisfied with the geometry it's time to get building.
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And another thought. Why not cut out most of the thin angled front part of the hood (I would leave juts 5 inches on each side for fitting over the wooden box and stability) and glue another plexiglass sheet cut to size, so your wife can look straight down when working, without cranking her neck or stepping back to look and letting fumes escape through the front opening (read here: use silicone to stick the plexiglass to the metal :-)
I like it!
Hehe, I could use this to burn up some stuff with extreme high voltage without stinking my shed!
great instructable
sorry, i keep forgetting what i want to say, i think this is the last post =P