An electrostatic discharge between postdoctoral researcher Thea Ekins-Coward and a gas storage tank containing hydrogen, oxygen, and carbon dioxide likely caused an explosion at the University of Hawaii, Mānoa, in which Ekins-Coward lost one of her arms, according to a report by the University of California Center for Laboratory Safety (UCCLS).
Safety recommendations for working with explosive gas mixtures:
▸ Calculate the potential explosive force to determine level of protection
▸ Compose detailed and thorough standard operating procedures
▸ Conduct specialized training on highly explosive materials
▸ Use well-designed, hazard-rated equipment (intrinsically safe as a minimum rating)
▸ Electrically ground and bond equipment
▸ Use blast barriers
▸ Use engineering controls for highly explosive materials
▸ Use work practice controls to limit access
▸ Conduct outside review of procedures, equipment, and engineering controls
Source: UCCLS, “Report to the University of Hawaii at Manoa on the Hydrogen/Oxygen Explosion of March 16, 2016,” part 2
UH hired UCCLS to conduct an independent investigation of the March 16 accident and released the report on July 1. Another investigation by the Honolulu Fire Department, released in April, concluded that the cause was a spark from the pressure gauge. UCCLS dug deeper than the fire department and contracted with an outside laboratory to recreate and test the experimental setup. Those tests ruled out all causes other than a static discharge.
Going beyond the immediate cause of the explosion, however, “the overall underlying cause of the accident was failure to recognize and control the hazards of an explosive gas mixture of hydrogen and oxygen,” the UCCLS report says.
“The message to other researchers is that they need to do a better job of educating themselves about the hazards of the materials they’re working with” and what could go wrong, says Craig A. Merlic, UCCLS executive director and a chemistry professor at UCLA. And campus safety personnel “need to have conversations with researchers and guide them to the resources that are available” to help conduct experiments safely, he adds.
In the case of the UH explosion, for example, the lab passed a safety inspection in January in part by properly storing H2 and O2 cylinders 6 meters apart. But no one questioned storing a mixture of the gases in a 49-L steel tank designed for compressed air and not electrically grounded, the UCCLS report says. When the tank exploded, it contained 55% H2, 38% O2, and 7% CO2 at a pressure of 8 atm. UCCLS estimated the energy of the detonation to be equivalent to 70.5 g of TNT.
Ekins-Coward was working for the Hawaii Natural Energy Institute under researcher Jian Yu. The gas mixture was used to feed bacteria to produce biofuels and bioplastics. Yu’s lab is still closed, and he and the institute have not yet determined how experiments will be set up going forward, says institute director Richard E. Rocheleau.
The explosion cost about $716,000 in infrastructure damage and $60,000 to $100,000 in equipment losses, and UCCLS was paid $88,000, says UH spokesman Dan Meisenzahl.
UH placed no restrictions on the UCCLS team during its investigation, Merlic says. The Hawaii Occupational Safety & Health Division is also examining the incident.