Two Flaming Loop Fires, both inside a Biological Safety Cabinet


Two reported laboratory fires, fueled by natural gas associated with the use of Bunsen burners should compel researchers to rethink how, and if, they should use them. Both fires occured at the University of X. Fortunately, no one was seriously injured.
 
In one case, gas leaked from a loose tubing connection and accumulated to where it was ignited by the burner's flame, causing a small explosion. Isopropanol in a nearby flask inside the cabinet also caught fire.
 
In the other incident, a researcher inadvertently turned on the gas thinking he was turning on the vacuum line. Realizing his mistake, he turned off the gas. When he subsequently attempted to light the burner, the residual gas in the cabinet ignited, burning his arms (first degree) and singeing his hair.
He had not waited long enough for the gas to dissipate.
 
Bunsen burners are typically used inside Biological Safety Cabinets for sterilizing inoculating loops and test tube lips. However, this task can be accomplished using a small electric "furnace" - a device expressly designed to eliminate the need for using flammable gas in a safety cabinet (available from Fisher) or consider using pre-sterilized, disposable loops.) Accidently released gas may also be ignited by sparks or heat from the motors and switches on cabinet fans and lights.
 
Consider these four points when using a flame: 
  • Use a burner equipped with a pilot light, in place of older models with a blow torch-like flame;
  • Do not use latex tubing (the stretchy yellow material). It tears easily and is prone to pinholes; use butyl rubber instead;
  • Check tubing regularly for cracks and tears;
  • Replace tubing at the first sign of wear or deterioration.