Hockeydemon
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Possible DIY fumehood schematics?
Hey everyone,
Been toying around on Google's Sketch-up trying to put together a decent fume-hood. This is a rouge sketch-up, and is not finished but I wanted to get
some input because it is my first go at designing a fume hood ha.
I need to add baffles and figure out airflow. I need interior gas, water, and vacuum attachments. I need to calculate the cfm fan required for that
area of space. I am planning on calling up a metal machinist to see if it would be wiser to get the entire thing made out of coated aluminium instead
of wood. The measurements off the top of my head are roughly:
4x4 legs
53 1/8" x 38 5/8" house window
37" wide box
6' 9" tall from floor
Actually I saw a fume hood someone had put together on here and that's where I got the idea to use a house window for the shield. I had spent hours on
Sketch-Up putting together this intricate sliding panel shield with fitted groves for the panels.. Ended up being a total waste of time once I found
the house window idea..
I can send the Sketch-Up file to anyone who asks for it, and it will have exact measurements. Any suggestions, things I'm doing wrong? Help would be
greatly appreciated . Advice when it comes to sealing the thing properly ect would be wonderful
**And of course don't forget the exhaust filter for the environment 
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radagast
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Those are roughly the same dimensions as my fumehood, which seems to work fine, so I think you're on the right track.
Magpie is our resident expert on fumehoods, so you may want to search for more of his information. I was going to post on my design in an independent
thread, but can give you a quick preview here. I think fumehood design comes down to the risks that your experiments create. E.g. are you using
pyrophoric reagents or other hyper-flammable solvents, any carcinogenic solvents, highly corrosive vapors, etc.
For me, I can't work with carcinogens, but am OK with working with flammable material, normal solvents like ethyl acetate, and typical mineral acid
vapors. In addition, I wanted to filter the air before it left. So I decided to construct an enclosure where I pulled apart a ductless used Air
Science hood (~$200), and adapted it so that instead of recirculating the air, it'd just pump the filtered air outside for additional protection.
Since ductless hoods operate at lower CFM to permit maximum adsorption and filtering, this meant that I couldn't work with any fumes that would
overwhelm the hood -- say, bromine and the like -- but it was very good at clearing out solvent vapors.
I built my entire apparatus out of Unistrut/Superstrut steel beams, which gave me the advantage of modifying my design as I built it. The walls,
floor, and ceiling were made from wood, lined with 1/2" fireproof cement backing board, which was additionally lined with sheet aluminum. For
additional protection, the floor was tiled with ceramic. The fumehood window was simply a large window from Home Depot.
Re: your question about seals: unless you're working with some seriously dangerous chemicals, I wouldn't worry too much about leaks since your hood
should run at negative pressure.
Anyway, sorry for rambling but I'll try to provide more concrete detail and pictures in an independent thread.
[Edited on 27-2-2013 by radagast]
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Hockeydemon
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Quote: Originally posted by radagast  | | Those are roughly the same dimensions as my fumehood, which seems to work fine, so I think you're on the right track. |
Your setup is wonderful! A support stand built in is Brilliant! I'll be sure to add that into my design. I am
very envious, I wish I knew anyone around my area with something like this that I could go hang out at.. I'm too aware of the time it takes to accrue
a real home laboratory on a college students budget..
| Quote: Originally posted by radagast | | E.g. are you using pyrophoric reagents or other hyper-flammable solvents, any carcinogenic solvents, highly corrosive vapors, etc.
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I was designing the fume hood specifically for an acetylation reaction with acetic anhydride.. No I am not
making anything illegal, how sad it is that I feel so compelled to constantly reiterate that. I was searching google for variations of 'DIY home
laboratory', just wanting to save some money on things I can make myself (which I find much more fun anyways) and all that comes up is "Meth Lab, Meth
Lab, Meth Lab". I'm afraid to even go ask my professors about various DIY concepts because I don't want to be accused of doing anything illegal.
Anyways! You've been very helpful thank you. I look forward to reading your thread! I'm very glad to have stumbled upon this forum.
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radagast
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No problem -- it might be a while before I post the other thread, though, due to work obligations.
I've worked with acetic anhydride on a mmol scale before, to acetylate the weak PI3K/mTOR inhibitor EGCG into its more potent pro-drug, which was
recently researched by GlaxoKlineSmith. It's quite the lachrymator, just as advertised. (That was in the hardy youth of my pre-fumehood days).
And, please don't take this directed to you as an accusation or as legal advice but just as a general cautionary note to everyone: acetylation of a
controlled substance to its pro-drug (or acetylation of an arguably totally different compound, which happens to be "substantially similar . . . in
structure/effect" to a controlled substance) will not necessarily bring it out of the purview of federal and state law.
IIRC, the caselaw surrounding the federal analog act treats acetyl-derivatives of controlled substances as equivalent to an official controlled
substance, and on top of that, many states have their own analog acts, each with its unique jurisprudence. Federal and state caselaw is quite hazy
and there is plenty of room for prosecutorial discretion. I would hate for someone with good intentions to get caught up in criminal/civil
litigation. Take it from someone who litigates for a living -- it is not a fun process.
[Edited on 27-2-2013 by radagast]
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Arsole
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In my experience Profs are very helpful if you can bring in a patent, journal article, or other source for the reaction you would like to try. Also
the designs you posted here are a good conversation starter.
You: "Dr ______ I am interested in the design of fume hoods and am looking for a cost effective alternative to commercial models. Do you have any
advice on ______" While showing the drawing/schematic.
Many chemistry profs are enthusiasts and would jump all over and excuse to think about a project. (Just don't pick the stuck up ones) Remember be
mindful of their time, failing all those O-chem students takes awhile.
If you don't have anything to hide it shows and most are willing to help out. If you do have something to hide they will know after talking with you
for about 5 min. Also, just like the forum, UTFSE don't waste valuable time with questions Google could tell you with 2 minutes of searching. Profs
might not give you a second chance if you waste their time.
Thoughts, like fleas, jump from man to man, but they don't bite everybody.
-Stanisław Jerzy Lec
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S.C. Wack
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Maybe you can just use what's at hand and smoke test until it's right, because you might end up doing that anyways if you do the math. BTW several
older models of that size or a bit bigger I've seen sucked most air from a baffled vertical channel in the back, which as you might expect changed in
depth and width from top to bottom, for even sucking power. An effective carbon VOC filter will obviously add HP to the motor spec.
Let us know the quote on the Al. Now we'll be watching to see if you end up with coated wood...
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