Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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How to build your own fume hood .... and fume scrubber
November 5, 2015
Take a milk crate (plastic) and cover it on three sides with some kind of plastic sheeting. Get a cheap blower from home depot and set it on top. Duct it out via some dryer hose to the outside air.
Don't expect too much of this contraption. But it is lots better than nothing. I used such a device for some years to protect my lungs from fumes.
Dave Wichern
Consultant - The Bronx, New York
October 2, 2015
Q. Good day / evening.
I have been reading this site as well as a few books that have been recommended here. First of all I haven't tried to process anything yet, though I am interested in doing so but am trying to research all aspects first. Would like to ensure I don't waste my time, hurt someone, the environment or myself first.
Now my problem is that everyone seems to feel that just being in the open air is enough for them where the toxic fumes are concerned -- that advice is all over. That's not good enough for me, I will set up a hood vent before I begin any processes.
My question, finally, is what type of filter medium can I use so that these fumes are not breathed in by me or my neighbours or the birds that may be roasting in the tree above my house. I am amateur, hobbyist and can't afford anything too extravagant,I know carbon acts as an amazing filter for just about anything -- would it work for this application and could I use carbon filters like those in fish tanks as they are reasonably inexpensive?
Neutralizing the acids themselves is pretty straightforward, but how do you neutralize the fumes or at least scrub them?
Sorry this is such a long post, trying to follow posting protocol. A bit about me and my situation.
Thanks Chris!
Building environmental system operator - toronto Ontario Canada
A. Hi Chris. We appended your inquiry to a later thread from Dave Wichern where he tells us how to build a simple fume hood.
Activated carbon is mostly for organic materials, not acids. But you may be able to rig up a simple wet fume scrubber from additional milk crates. The "fumes" are either tiny droplets of acid or they are gasses which are soluble in water, and the principle of wet fume scrubbing is to expose those "fumes" to a lot of water to recapture them in the water (from which you can bleed some off as it gets more concentrated, and waste treat it as you would a dilute acid, which is what it is).
In a conventional packed bed fume scrubber (look up 'horizontal packed bed fume scrubber' for some graphics), the exhaust gas passes through a box packed with plastic raschig rings or berl saddles or similar shapes with a lot of surface area, while spray nozzles keep the packing wet, with the drips collected and recirculated back to the spray nozzles. The exhaust air can only get through this labyrinth by making a lot of twists and turns, and the convoluted 'walls' the air stream must follow are all little waterfalls, presenting lots of opportunity for the droplets to impinge into the waterfalls and the gasses to be re-absorbed. If you can accumulate some plastic shapes, you could try to build a simple and cheap fume scrubber and learn from the exercise. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 2015