When C&EN published my story about the fire department investigation into the explosion at the University of Hawaii (UH) that cost postdoc Thea Ekins-Coward one of her arms, we got many comments about whether or how the gas cylinders were secured. The fire department report and photos had little information about that issue. The University of California Center for Laboratory Safety (UCCLS) report released on July 1, however, devotes a section of its recommendations to how gas cylinder safety could be improved at UH.
Note that Honolulu is not at high risk for earthquakes–according to the U.S. Geological Survey, it’s roughly equivalent to Sacramento or Las Vegas. Consequently, things that Coastal California scientists might need to do, such as double-strapping cylinders, are not required. That said, there was still room to do better.
This group of ten cylinders, for example, which included hydrogen, carbon dioxide, helium, and carbon monoxide:
Was secured as:
The typical gas cylinder clamp with cloth strap is only designed to support a single cylinder. Thus, a cluster of ten cylinders should be in a dedicated gas rack. Second, only cylinders of similar size should be secured together. Securing large and small cylinders together results in one cylinder size being secured at the wrong height. (Technical report, page 9)
As for the two oxygen cylinders:
● Both oxygen cylinders were strapped to the biosafety cabinet with a safety strap as required by OSHA and CGA P-1. However, the safety straps of both cylinders loosened as a result of the force of the explosion. Although not required by HIOSH, chaining gas cylinders presents a safer option.
● One of the oxygen cylinders was open when the explosion occurred and vented its gas content into the laboratory. However, it did not cause an oxygen enriched fire which would have led to more damage and possibly cause the adjacent oxygen cylinder that was closed to vent through the CG-1 (Rupture disk) pressure relief device. (Technical report, page 30)
In another lab, UCCLS found this one, captioned “Gas cylinder attached to an adjustable shelf in a bookcase.” I don’t know which lab this was in, but judging from the mess on the floor and exposed insulation at the back, I’m guessing it was one of the labs adjacent to the one in which the explosion happened. The report notes that for two adjacent labs, cabinets were blown off the walls.
UCCLS’s overall guidance on gas cylinder storage and use (Recommendations report, pages 7 to 10):
- Gas cylinders should be restrained by chains secured to a wall with Unistrut steel bars. In earthquake areas there should be two chains placed at ⅓ and ⅔ height on the cylinder.
- Store unused cylinders with the valve protection cap in place, not uncapped or with a regulator.
- Do not use Teflon tape on cylinder outlet valves.
- Do not use leaking, aged regulators.
- Support and label gas lines.
- Do not use plastic tubing such as polyethylene for hydrogen gas, or metallic materials for oxygen systems.