Use a fume hood or other ventilation for indoor work
It is important to use a fume hood or work in a well ventilated area when using n-butane or other volatile solvents and chemicals.
- A fume hood would be used for the extraction apparatus to remove gas.
- Fume hood is used for toxic volatile solvents like torlene (sp?) which is common in TLC.
- A water aspirator would be used for boiling off the ethanol to remove gas (and lower pressure).
Its not hard to build a portable fume hood using plexiglass and a little math.
The fume hood will have to be large enough so the extraction apparatus can fit inside.
I will do a pictorial how to when I build one, but here's the dirty:
Build a three sided box, say 3'x2'x2' (LxWxH), although a truncated triangular footprint might provide better air velocity. Attach a removable 'front' piece of plexiglass with an opening of around 2 feet (enough room to comfortably work). Build an upward sloping 'roof' (like a house's roof). At the center of the roof attach a squall cage fan or in-line fan which can provide a "face velocity" of 90-100 ft/min. If one can't reach a minimum of 80 ft/min than decrease or increase the size of the opening accordingly. Attach a 4" plastic drier hose to the fan and vent it outside.
That's it. Now when extracting with n-butane do so within the fume hood.
"Design for a Miniature Portable Fume Hood
By: R.A. Bailey & S.C. Wait, Jr. J. Chem. Educ. 76(2), 228-229 (1999)