Chemical Plant Explosion and Fire in East St Louis

News reports out (here, here, here, here, and here) describe an explosion and fire that happened last night at a chemical plant in East St. Louis, MO. The reports are all sketchy, a tank of some sort exploded in the facility and there was a fire as a result. Two people were injured, one in critical condition with ‘chemical burns’ to a large portion of his body. Both went to the hospital, so this is a CSB reportable (40 CFR 1604.3) incident, but that agency is unlikely to investigate. OSHA is on scene, of course. Lots of large fines for sins unrelated to the fire are to be expected.

None of the reporters were able to identify the chemical involved beyond the fact that it was water soluble (‘water solvent’ in one case). Two of the articles implied that once the fire department was made aware that it was water soluble, they were able to proceed with using the building sprinkler system. That system should have started automatically. I think the concern here was the problem of adding water to an oil or grease fire, the flammable liquid floats on top of the water and can spread the fire. That can be a legitimate concern, but flammable liquids dissolved in water in sufficient concentration can turn the water into a flammable liquid, spreading the fire as well; this is especially true of ethanol and methanol. In fact, I worked on a process once where we had to capture wash water from a product we made because at 4% solubility with an organic solvent, the saturated water had a flash point of about 100˚ F. It would not burn long (not enough fuel), but it would flash.

Looking at the damage to the building (good daylight picture here) this was not much of an explosion. This indicates that it was probably not a pressure-rated tank that exploded. A flashfire contained in the headspace of a non-pressure rated tank can produce a respectable bang and enough overpressure to blow out nearby windows. Too early to tell what caused the initial fire/explosion.

At least one article quotes a local fire department official as saying: “However, a lot of the fire we found was still up over the sprinklers and so the sprinklers couldn’t get to it.” Google satellite view® of the building show that it is membrane coated roof so there may be a wood roof under the membrane. Burning liquid could have been thrown up to the underside of the roof, that could have started it burning and many sprinkler systems do not adequately wet that surface.