Electrostatic Discharge Ignited Lab Explosion

photo by Daniel RamirezInvestigators have discovered the cause of a March 16, 2016 explosion in a laboratory at the University of Hawaiʻi at Mānoa that seriously injured a researcher. The 29-year-old woman lost an arm and suffered other injuries during the event that occurred while she was conducting an experiment involving a mixture of hydrogen, carbon dioxide, and oxygen gases in high-pressure tanks. An initial report blamed the event on an issue with the pressure gauge that the researcher was using at the time of the incident. Now an investigation by the University of California Center for Laboratory Safety has concluded that the most likely cause was actually electrostatic discharge between the researcher and the storage tank.

The same experiment had previously been conducted 11 times without a problem, but the day before the accident, the researcher noticed a cracking sound that indicated that a small combustion had occurred within the tank. She reported the event to her team, but unfortunately, the researchers dismissed this minor event as an anomaly and continued operations. A technical report explains, “it is surprising that the incident did not occur earlier.” The gas mixture only required a small amount of energy to ignite, and neither the gas storage tank, the incubator, nor the researcher were properly grounded. The discharge occurred when she touched the metal housing of the pressure gauge. The report states:

A key finding was that the plastic face of the digital pressure gauge where the On/Off switch is located is electrically insulated. Since the postdoctoral researcher reportedly pushed the gauge’s On/Off button when both incidents occurred, she could have only created a gateway for the electrostatic discharge when she also touched the gauge metal housing, which is conductive (charge transfer).

The Investigative Team also suggests that a stray electrical current within the digital pressure gauge circuitry could have caused an electrical transfer to the tank’s interior, although they weren’t able to recreate this scenario during tests. Since the March accident, the university has taken steps to improve lab safety. They created a new safety committee and have implemented safety peer-reviews among researchers and laboratory staff. All campus labs working with high-pressure gases, flammable, or explosive materials have suspended operation and are still in the process of completing safety reviews of all activities and equipment. UH Mānoa Vice Chancellor for Research Michael Bruno said:

Our goal now is to become a national leader in laboratory safety. It’s about enhancing our safety culture and standard operating procedures where risks are constantly being identified and minimized. Everybody has a role to play.

Source: UH Mānoa | Photo by Daniel Ramirez

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