The UC Center for Laboratory Safety

What happened?

A staff researcher was walking by a fume hood when an explosion inside the fume hood occurred. The explosion caused several glass containers to break. The researcher sustained a laceration to the left middle finger and pieces of glass were embedded into the researcher’s right middle fingernail. Fortunately, no major injuries occurred, and there was no sign of a fire. 

What was the cause?

An undergraduate student researcher in the lab had been using a dry ice/acetone bath to cool a chemical reaction earlier that day. At the end of the procedure, the acetone was poured into a glass waste container in the fume hood and the container was capped. As compared to ethanol or water, CO2 is highly soluble in acetone. It is likely that the acetone still contained dissolved CO2 from the dry ice, which was released as the acetone warmed resulting in an explosive build-up of pressure.

What corrective actions were taken?

• The incident was discussed with the laboratory group.
• The lab group was provided with vent caps.

How can incidents like this be prevented?

• Whenever working with dry ice or other cryogenic materials, be aware of the potential effects of bringing these materials to room temperature, especially in sealed containers.
• Treat all solvents used with dry ice as potentially containing some amount of gaseous CO2. Allow the solution to warm to room temperature in a fume hood in a container initially with a vent cap, which can be replaced later.
• The American Chemical Society recommends replacing the volatile acetone in cooling baths (-78°C) with 2-propanol (-77°C).
• Vent caps should generally be used for pressure-generating chemical waste.
• Closing fume hood sashes can help prevent the spread of contamination or debris if a chemical storage container fails. In general, when fume hoods are not in use the sashes should be closed.

 Resources

• Acetone SDS
• Dry ice SDS
• Vented cap experiment video