cynlabz - 15-7-2010 at 16:37
After months of procrastination, I finally plan to begin with the painstaking construction of my home lab. So far I am in the process of assembling a
heavy- duty shelving unit for chemical and glassware storage. I have a small wooden table, which due to its flimsiness, I will likely have to
reinforce, and then there’s the fume hood to be made. My lab is to be in the basement of my residency, and while I don’t plan to conduct reactions
that will generate copious amounts of gaseous products in the home, I do plan to deal with a variety of toxic organic solvents including
methanol, toluene, dichloromethane, chloroform, diethyl ether, acetone and dimethyl sulfoxide, whose use and storage would be quite a
concern. Having deduced after momentary thought that I would not like to suffer any adverse effects associated with trace accumulation of solvent
vapour, and the resulting chronic exposure 
, I decided that installing a
makeshift fume hood would be my best bet. (I also plan to do some inorganic syntheses, and would prefer to keep the area free of dust. 
)
Being a pitiful handyman and engineer, and finding no low cost fume hoods for purchase locally, I have instead decided to purchase a very good second-
hand range hood from a friend. At peak capacity it is capable of filtering a grand total of 68.4 cubic metres of air per minute, which in comparison
to the standard capacity of some fume hoods (UTSE) is actually quite good. The range hood is interconvertable, and can be made to function with vented
ventilation, or otherwise a disposable charcoal filter can be used. My lack in construction prowess would make me inclined to favour the latter
however this leaves me with some questions – How efficient would an activated charcoal filter be in filtering organic vapours, or those
of common acids like hydrochloric? I'm also a tad confused as to how to know when the filter's disfunctional and must be replaced. Would
anyone with some practical experience give me some recommendations or advice?
Also, seeing as all I have so far (as far as my plan goes) is a range hood mounted onto a wooden frame, I was wondering as to whether it
would be okay to simply lock in place sheets of translucent polyethylene vapour barrier, so as to enclose the hood (in place of wooden, or metallic
walls)? (Or would this somehow be detrimental from a safety standpoint?)
-tnx
-cynlabz
densest - 15-7-2010 at 20:13
Are you planning to heat anything inside your hood? Plastic sides plus a splash of solvent = very flammable. I'd think about plywood walls with epoxy
paint or some flame-resistant paint. Aluminum foil reflects heat remarkably well and is not affected by organic solvents, but it will dissolve with
acid or base fumes.
I can't speak to efficacy of charcoal filters, but I'd replace them as soon as I smelled anything at the output.
zed - 15-7-2010 at 21:47
No. Don't do it. No range hood. Quite possibly, it will be your doom.
There are many threads devoted to hood construction, here at Science Madness. Read them.
Seems to me, there is a fairly explosion-proof squirrel-cage blower that you can buy on e-bay for a hundred bucks or so.....Build your fume hood
around that.
The long term health effects....caused by trace amounts of solvents in the atmosphere....won't matter much, if you blow yourself up and set your house
on fire, by playing with diethyl ether, near a range hood motor that produces sparks.
Contrabasso - 16-7-2010 at 00:32
You need to be handy enough to get the fixtures right, or you need someone who is!
The best fume cupboards I've seen were glass inside and polycarbonate outside double glazed. You could put anything inside that was glass safe (that's
most things!) and if it blew up then the polycarb would catch the blast.
The fan needs to be in the airflow, BUT the motor is best out of the flow, also it's best if the motor is spark less. However you don't want the thing
too powerful or you can never get the temperatures you need for the cooling wind.
Think also where the fumes are going! You don't want the wind to blow them back into the house, or into the neighbour's house.