Carbon Disulfide Fire

Key Instruction Points

  • Store liquids in stable containers or use racks.

  • Recognize location of nearest ignition sources when using flammable liquids

Incident Description

We have four gas chromatographs (GCs) on two sides of one ten-foot-long aisle of our laboratory. One of our analysts was working at one of the GCs and was choked by a cloud of some sort of gas of an unknown origin and nature. After looking around for a second or two and not finding the source, she called out for everyone to get out of the lab and set off the fire alarm in the hallway, waiting for the Fire Department HazMat team and finally our own staff to identify what the problem was.
 

What we finally discovered was the following: another analyst in our lab, a contractor, had set an open vial (with an inward-tapered opening at the top) of carbon disulfide, used for flushing GC autosamplers, on top of another GC across the aisle. Somehow, the vial tipped over and rolled into the opening at the top of the GC where the heated injector is located.  

Presumably the CS2 heated up the vial when it came into contact with the injector, and sprayed out CS2 vapor. The vapor burst into flame (because of the very low auto-ignition temperature) when it came in contact with the injector, producing a nearly-suffocating cloud of SO2 and unburnt CS2 which passed over the other analyst, moving in the direction of the nearby fume hood. The entire incident was over in perhaps 10 seconds (but we didn't know that at the time)! 

The analyst who breathed the combustion products was checked and found to have suffered no ill effects. The GC where the fire took place has a few scorch marks around the injector, but otherwise suffered no damage. The lost time of the several hundred people that work in our 7 story building and were kept outside for about 2.5 hours was significant. 

The primary cause of the incident was putting a narrow-based vial with a highly flammable solvent on top of an instrument.  

We put a stop to the practice of putting things on the top of Gcs immediately. After the incident we had the carpentry shop fabricate a half dozen small tube racks that will hold GC vials of the appropriate size. There is one such rack next to every GC in the lab now. We have established a rule that nothing will be put on top of any GC - or any other instrument - but only in a rack, on the bench top.  

We were fortunate that we had no injuries or property damage, but the cost in lost time to ourselves and others in our building was significant.