unless someone also “upgraded” the breaker That happens. 10 years ago or so there was a big explosion at the University of Texas, Austin. The Chemistry Departm

unless someone also “upgraded” the breaker That happens. 10 years ago or so there was a big explosion at the University of Texas, Austin. The Chemistry Department had a storage vessel for liquid nitrogen. Of course the cold liquid evaporates and creates pressure inside the container. Typically the internal pressure is held at 1.5 bar by means of an escape valve. The escape valve failed and someone replaced it with a solid brass plug. To prevent accidents if the escape valve fails there is also a burst disk that breaks at higher pressure but before the tank itself explodes. That mechanism worked as designed, it released pressure, so they replaced the emergency release valve with a brass plug as well. One nice night the burst pressure of the tank itself was exceeded, and the bottom launched itself through the floor. The top was stopped by a concrete beam, but it did break a few water pipes. Here's the report from the Fire Marshal: https://www.tdi.texas.gov/fire/documents/fmred022206.pdf https://www.tdi.texas.gov/fire/documents/fmred022206.pdf There is no need to test if safety equipment works, because sometimes it does not.