Painting, spraybooths and explosion proof fans

QUOTE: In a commercial installation, "explosion proof" or "hazardous area" motors and bearings are required. But, the bottom line is, paint solvents have a higher combustion temperature point than any spark that such a fan could generate. It won't happen, and I've never heard of it happening. It does happen with cooking grease that is vaporized, but that is because the hot grease is expanding from heat while being compressed into the exhaust chamber, not due to sparks. The physics won't allow it, but there are those who might argue the point with me. I was in a spray booth explosion when I was 13 that was caused by a broken incandescent lamp. No fan, and the booth was full of alkyd enamel fumes. It went poof! Was a flash, hot of course, and over in a split second. No damage other than a mild sunburn. There isn't a fuel source to continue a blast or fire, so it is over quickly. There really isn't that much flammable material in the overspray vapor. Figure you are shooting a spraygun with a 1 qt can. You will mix it maybe half full of the stuff you want to do at most. That's 16 oz total, 85 % goes on the surface, and 50% of the remaining 15% is solid, non explosive material. Half of the remaining 7.5% evaporates immediately upon leaving the gun head. That leaves 3.75% to go through a fan (solvents). That means, that if you could put the entire gunfull in the air at precisely the same instant, you would have 6/10 of an ounce of solvents in the air. Go outside, and pour 6/10 of an ounce of reducer out and light it. It won't even light a charcoal grille. And, you can't put that much in the air at once anyway.