Two scientists were changing hydrogen gas cylinders in an analytical laboratory. They were in the process of removing the cylinder cap from the new cylinder when a loud hissing noise occurred and they quickly realized that the tank was leaking. After making a quick attempt to shut off the tank, which was not possible, they left the lab and notified their supervisor.

After checking that everyone was out of the lab, the supervisor paged all staff in the vicinity to immediately evacuate to the staging area. Facility management and ES&H management were notified about the situation, and they contacted the local fire department to respond to the site in case the venting gas was ignited.

The first responders arrived quickly and spoke with facility management and the site view more

An individual inadvertently connected a pure hydrogen gas bottle to a chamber/glove box as opposed to a 10% hydrogen (in nitrogen) bottle that should have been used. [The wrong bottle had mistakenly been delivered, and the inexperienced individual did not know the difference.] The hydrogen concentration increased within the chamber to about 9%. Since there was insufficient oxygen in the chamber to support combustion, the hydrogen did not burn, and was quickly diluted with nitrogen.