Biodiesel and Drills

By Rick Da Tech


Using a drill to mix biodiesel can result in serious injuryBack in the bad old days we used drills and paint stirrers to mix biodiesel. It was a cheap easy way to mix both biodiesel and methoxide. The problem is that it's excessively dangerous. Methanol at any temperature and hot biodiesel being processed give off methanol fumes. When methanol vapor concentrations around the drill reach 6%, the sparks from the drill will ignite the methanol. It will form a fireball centered on the drill. Since your hands are holding onto the drill they receive 3rd degree burns as do your forearms. Your upper arms, chest, neck, and face receive second degree burns and any exposed chest or facial hair instantly become ash.  The next thing you know, your on your way to the hospital to get treatment for burns that cover a quarter of your body.

From "The Register" 28th July 2008

A Northamptonshire man destroyed his garage and badly injured himself at the weekend while attempting to make biodiesel from used cooking oil. A devastating explosion levelled the makeshift reprocessing plant on Saturday afternoon, when sparks from an electric drill being used to mix ingredients ignited explosive vapours.

Firemen hastened to deal with the smoking wreckage, in Middleton Cheney, and the unnamed thrifty motorist was airlifted to hospital with 20 per cent burns.

One of the first developments in the bad old days was to hard mount the drill. That way when it exploded, at least you were not in the center of the fireball. But that didn't protect your shed from burning to the ground. The early developers then found that if they semi-sealed their processor with a lid and ran the paint mixer through a small hole, then they could process with less methanol being lost to evaporation. This of course meant it took longer to reach explosive levels. The key is that it took longer to explode, it did not prevent the explosion.

Very Plainly - Drills and Methanol do not mix - they EXPLODE.

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