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How can I make a fume cupboard/ fume hood? Answered

Hi all!
I am trying to make my own fume cupboard/ fume hood to keep my acids in for my jewellery workshop, I am unsure what type of fan I need to suck the air out? The fume box will sit bellow a window so should I attatch a pipe from the back of the box to the window? If so, how does the air get sucked out?



Go to a hardware store and get a range hood, i bought my mom a cheep one for like 25 bucks. Then you just have to build the sides if you want.

If you just want a ventilated storage area (i.e. not a space to work in) use a small bathroom-extractor, you should find a louvre vent and piping in the same retail-section.



8 years ago

What you are need to build is a vapor (vapour, if you use the British spelling) recovery/vent system. In a vapor system you never want the electrical components in the vent flow for reasons others have already stated here.
The easy solution is to use a squirrel cage fan with an external motor. Once you have the squirrel cage fan it won't be difficult to design a vent system using non-reactive plastics and materials around the fan and a carbon filter box to safely and efficiently vent the acid fumes.
I suggest you start with procuring a small squirrel cage fan and then working from there. You can find them for sale new on the net for about $50-$60.
Here is a picture of a squirrel cage vent to give you an idea of what you need.

squirrel cage.jpg

For some fumes, you would need to worry about a spark igniting them. Acids shouldn't be a problem in that regard.

The fan should be arranged to draw air from the hood into the vent pipe.

Be slightly careful; if wind exceeds the pressure producted by the fan you could get reversal of flow. You probably want to limit that (and heat loss when the hood isn't in use) by using a flap cover simliar to those used for other vent fans (bathrooms, kitchens, etc.)

That pretty much exhausts (partdon the pun) my ability to advise. I've bene thinking of doing something similar as a paint hood, but for that I *would* need to worry about getting a non-sparking fan and making sure the ducting is grounded... I think.


8 years ago

Assuming the fumes will never be flammable or explosive (solvents?) then get a muffin fan out of a trashed computer and mount it in a 3 or 4 inch dryer hose, routed out the window. Watch out because the acid fumes will eventually eat the fan motor and kill it or short it out, fire hazard. The fumes will also start eating whatever they blow on at the other end of the hose. You might put a neutralizing filter between the fume box and the fan..sodium bicarb? should work.

you can use any type of fan. of course more fumes means bigger fan. a fan sucks the air/ fumes from one part and pushes them trough the other. in which direction it will push the air depends on blades position. you can do simple test: turn the fan on and check which side sucks and which pushes.

i would also suggest you check connectors and wires on fan motor in order not to blow up the room when you turn on the fan. the pipe trough the window is OK.