The UC Center for Laboratory Safety

What Happened?

A researcher conducted an experiment in which dicyclopentadiene (DCPD) was heated inside a Teflon inner chamber contained within a stainless steel body, also known as a pressure chamber or vessel. She placed 320 ml of DCPD inside the 500 ml pressure vessel, which had been purged with nitrogen gas. The Teflon chamber was closed and tightly secured by screwing on the lid of the outside steel container. The researcher had performed the same experiment about 12-times before but this time she placed the pressure vessel inside a gravity oven, directly on top of a heating coil. In her previous experiments she had place the vessel between two heating coils. A thermocouple placed on top of the vessel was used to monitor the temperature. The target temperature for the reaction vessel was 162 ºC. The plan was to turn off the oven when the vessel reached 150 ºC with the expectation that the vessel would continue to heat up to the desired temperature and stabilize. However, the researcher noticed that the temperature of the vessel increased much faster than expected, and when the temperature reading passed 160 ºC, she opened the oven door to allow the vessel to cool more quickly. As soon as she opened the door and barely glanced at the pressure chamber, a blast knocked her to the ground.

The researcher was able to stand up, walk outside the laboratory into the hallway, and call Campus Dispatch with her cell phone. Emergency personnel arrived and transported her to the ER for treatment. The researcher sustained cuts to her face and chest, and temporary bilateral hearing impairment.

At the time of the incident the researcher was alone in the lab and was not wearing PPE as she did not expect to come in contact with the chemical.

What Was The Cause?

The explosion was most likely caused by placing the pressure vessel directly on top of a heating element. This likely caused the vessel bottom to become much hotter than the temperature probe on the top indicated. Above 150 ºC, DCPD decomposes to flammable gases causing rapid buildup of pressure in closed systems, which could have exceeded the pressure limits of the vessel.

What Corrective Actions Were Taken?

• Use this incident as a lesson learned and discuss emergency procedures and best practices
• Generate a SOP for experiments involving the use of a pressure chamber
• Review required PPE when using DCPD and pressure vessels; PPE should include goggles, a face shield and the use of blast shields

How Can Incidents Like This Be Prevented?

• Closely follow manufacturer’s recommendations for devices
• Do not place steel containers directly on top of a heat source; steel is a good temperature conductor
• If uneven heating of an experimental device is possible, consider using an IR temperature sensor to monitor different sections of the apparatus

Resources

• Safety Data Sheet for Dicyclopentadiene (DCPD)
• UCLA EH&S fact sheet on pressure chambers
• Lessons Learned: Pressure Vessels