We've had a lot of comments at C&EN about my story, "Spark from pressure gauge caused University of Hawaii explosion, fire department says." I thought I'd flag a few of them here:
I am a researcher in the same building as the HNEI, although not on the same floor, and not in the same field. We felt the explosion rattle the floor and walls eight floors up - Dr. Ekins-Coward is truly lucky to be alive. The incident has prompted campus-wide laboratory safety re-certification efforts here, particularly with regard to pressurized gas cylinders, whether or not they contain flammable gases. PIs, please take the time to discuss with your lab staff and students proper gas handling - students and staff, if you see red flags, don't let up until your PI fixes the issue. It really sucks having something like this happen in your University, let alone your own lab building and community.
I can empathize with this researcher..... I work with Hydrogen, CO, and O2 in the lab and did not consider the issue with fires.... I will conduct a SAP review and modify our current working conditions. I teach a safety course and work closely with SAChE but and aware of the LFL and UFL of H2... we as researchers get tunnel vision. I am very sorry it took someone to lose an arm for me to realize the danger I put myself and my researcher at.... I know better.
Where I work, an experiment of this type would never be allowed to become operational until a subject matter expert (or probably a team of them, in this case) fully inspected the design and the operating parameters. Especially if the system was built by a new member of a research team. A full hazard control plan, in writing, would be written up and signed off by anyone touching the experiment. In my world, the subject matter experts are drawn from research scientists familiar with the experimental designs.
Since it was a pressurized system containing an explosive hydrogen gas mixture, I suspect that at minimum, there would be an emphasis on a design that minimized risk including volume limits, an inspection for electrical safety, and likely, some sort of containment system would be incorporated to protect against just this sort of catastrophe. A reviewer would probably ask "is there a safer way to introduce the gas mixture into the reactor?".
These sorts of intensive safety programs add time and cost to the business of doing science (but are ubiquitous in industry and government labs), but the flip side is what we see in these pictures: when things go wrong, they go very, very wrong.
The spark energy limitations of intrinsically safe apparatus are normally assessed considering flammable component when mixed with air at atmospheric conditions. If this mixture was being prepared form pure gases, then there is a real of preparing an oxygen enriched atmosphere unless the order of mixing and the concentrations were limited to ensure the inert component (CO2) was always at least x5 the oxygen concentration (giving a similar dilution as nitrogen in air) and the oxygen concentration could never exceed 21%.
The point being that any explosion protected equipment, including Intrinsically safe apparatus would need to have been specifically approved for an oxygen enriched atmosphere. The spark ignition properties are some X10 to x20 more onerous in enriched atmospheres. NFPA 53 gives some guidance as to the risks. Managing pure oxygen or oxygen at pressure also imposes its own ignition risks without need of any spark assistance from non-explosion protected equipment.
Everyone loves to conduct research at universities vs. a private or government research laboratory due to cost. Part of the "cost savings" of university laboratories is due to the lack of environmental safety and health support, they don't have knowledgeable people to address these issues. They also don't have proper engineering support to design systems.