Vacuum Flask Incident

A researcher at the University of Delaware was performing tissue culture work. They had a vacuum flask set up to aspirate the cell culture media off the samples. This consisted of a 4 liter flask with tubing and a pump for the suction. The flask and pump were sitting on the floor below the biosafety cabinet. The flask contained a small quantity of cell culture waste and sodium hydroxide pellets had just been added to inhibit bacterial growth. Cotton from a pipette became lodged in the vacuum tubing. The researcher was advised to aspirate liquid through the system to dislodge the cotton. Water was aspirated in hopes of clearing the clog. Instead, the flask exploded sending shards of glass and liquid throughout the room. No one was cut by the flying glass, but the researcher was splashed with the concentrated sodium hydroxide. The researcher had been wearing a lab coat and safety glasses as required, but received a splash to the forehead just above the glasses. The researcher immediately removed the contaminated safety equipment and flushed their face in the eyewash. Public Safety and Environmental Health & Safety were notified by a second researcher in the room at the time.

Upon investigation, it was determined that the water reacted with the sodium hydroxide causing an exothermic, or heat-producing, reaction. The flask being used was a standard flask; it was not designed to be used as a vacuum flask.

Lessons to be learned:

  • Safety glasses do protect your eyes from hazardous material accidents that occur when you least expect them.
  • Use a flask designated as a vacuum flask. These are heavier glass and are less likely to shatter.
  • Wrap a vacuum flask in tape or place it in a plastic secondary container to minimize the hazard of flying glass in case the flask breaks.
  • Include a pressure-relief valve in the design of your vacuum system to minimize the risk of pressure building too high.
  • Use a disinfectant with a low hazard level. Bleach is effective for most tissue culture work. Always check the compatibility of the disinfectant with any other materials being added to the system and verify its effectiveness against any biological materials.
  • Never work alone with hazardous materials. This researcher was fortunate to have someone with them to call for help as they washed in the eyewash.