Ok, I understand OSHA and all and I wanto build a small can/airbrush painting booth in my house. I need about ~700CFM to push the air, however here’s my question. I’m supposed to buy a squirrel cage fan for explosion safety. These are freaking expensive, surplus, so I found some 28Vdc muffin fans (Inline). What I’m wondering is, is the V/I low enough that the fumes/vapor will not flash? What IS low enough that I won’t wake my family up with a boom?
I wouldn’t risk it. It’s possible that brushless DC fans would be safe enough, but with the electrical connections in the path of the flammable vapors, there’s always the risk of a spark. This is why a squirrel cage blower is recomended, since all the electrical connections are exterior to the area being ventilated. Any spark is a risk of explosion in an atmosphere of flammable vapors and air, under the right conditions.
Instead of using the fans to pull air from the room, which would put them in the vapor flow, how about placing the fans to push fresh air into the room and push the vapors out? That way there would be no chance of fire or explosion.
That might work if the room were 100% sealed from the outside, except for the outlet in the fume hood, but that’s rarely the case. Still too risky, IMO.
I did this on a temporary basis once in my garage. I built a frame out of 2x4s, covered it with clear polyethylene, sealed the seams with duct tape (it had a flap entrance on one side). I used a supplied air respirator to breathe.
-FK