Spontaneous Combustion

Spontaneous Combustion sounds like something out of a science fiction horror novel, but it’s real. Not only is it real, but among homebrewers its downright common. There are bacteria all around us. Some bacteria like to eat oil. In the process of eating the oil they heat up. A pile of rags make for good insulation and it’s not too hard for the little bacteria to heat things up enough for the rags to catch fire.

The solution is for you to put your oily rags in a metal can with an airtight metal lid. You can get them at most welding supply stores as well as on the internet.

Testimonials from Infopop

I’ve included four first hand reports of spontaneous combustion from the infopop biodiesel forum. These are just a few of the first hand reports. Searching there brought up report after report of spontaneous combustion, both first hand and second hand reports. This stuff is real and it is one of the most likely ways you’ll start a fire in your biodiesel production area.

About 3am this morning, my wife and I wake up to a weird, chemical-type smell. It was coming from the cellar, where I do my processing. When I am working down there, I have an exhaust fan running, but otherwise it has terrible ventilation. My eyes started watering and I was getting short of breath, which should have been my cue to leave. However, I figured I needed to find the source. After checking out the processor, hotplate, etc. I happened to brush against a laundry bag full of filter cloths & rags that I had just brought home from the Laundromat and it has hot! I threw the bag outside and got all the stuff out and sure enough, most of the rags and cloths were black and smoldering. The combination of the oil left in the material, the heat from the dryer and the fact that I crammed all of this stuff back into a laundry bag must have been enough to get them burning.

My wife almost set the house on fire today. She gathered up all of my greasy shop rags and washed and dried them. She then put them in a garbage bag and set them in the garage right next to the door coming into the house. They did not get washed very well and were still slightly oily. When I got home from work I went in the garage and found the bag melted and the rags burning. These rags were brand new prior to being used solely to wipe up wvo and biodiesel. Whatever you do, do not pile up your contaminated rags. Keep them spread out.

I’ve already experienced a spontaneous combustion with BD. "I" let my mist wash tank overfill with water and of course the first thing out of the tank was BD. "I" lost less than a gallon. My wife took some of my old t-shirts to clean it up. When she was done she piled the rags outside on a cubee of glycerin still loaded with methanol no less. "I" was not there when all this happened, (she was doing a mist wash and yet, somehow, she says "I" let it overrun), anyway when I came home that evening she told me about it and said it was already cleaned up so I didn’t go back to check. The next morning I was in the mule headed back to the lab and I could see smoke. I hightailed back there to find the pile of rags smoldering. I grabbed a stick and started picking the pile apart and slinging the rags onto the gravel. As each rag was exposed to air (when I slung it) they burst into open flaming balls. The top of the little cubee was all melted down and couldn’t be more than moments from melting through. There were 3 cubees there that would have burst into flames, probably had just enough volume of fluid to run down the hill to my big shop. The big shop is all metal and concrete but it still would have scorched the metal siding and made a mess. Needless to say, we don’t pile rags anymore.

I pre-treat incoming oil by heat-drying followed by quiescent settling of fine solids. The 700 litre settling tank is well insulated with raw sheep’s wool fleeces encased in reclaimed steel roofing sheet. The filling pump is wired through a float switch to prevent over-filling. This week I disabled the switch for maintenance (BAD MOVE).
Hot oil leaked from the switch aperture and soaked into the wool before dripping out the bottom. Bad enough having to clear up the mess, but worse was the following day when smoke was wafting out from under the lid. Yes, it had spontaneously caught fire and was quickly extinguished - lucky I was around! The wool will now be replaced with mineral fibre.