Hydrogen is a colorless, tasteless, and odorless gas. It is lighter than air and disperses rapidly. Hydrogen is highly flammable and forms an explosive atmosphere with air over a wide concentration range. The lower explosion limit is reached at 4% hydrogen and the upper limit at 74% by volume. Any concentration within that range can be easily ignited by a spark, heat, or static electricity.
A hydrogen explosion is a violent event that can cause severe damage or destroy a building, as seen in the 2010 explosion at the University of Missouri. The explosion caused approximately $750,000 in damage.
Image from June 29, 2010 Chemical and Engineering News
Anaerobic chambers often use small amounts of hydrogen and a catalyst to remove trace oxygen from the atmosphere through the formation of water. These catalysts can ignite explosive gas mixtures without an ignition source. Incubators, fans, and stirrers are commonly used inside anaerobic chambers and can cause ignition.
Accidentally filling the chamber with high levels of hydrogen or air leaking into the chamber can cause a fire or explosion.
All employees and students should be trained by an experienced person on how to safely use an anaerobic chamber before being allowed to use it.