[NOTE: the attribution to hydrogen formation as cause of the explosion is 'probable 'but not fully demonstrated].Two explosions in two different sprinkler systems occurred, wit the same assumed cause.The first occurred at the premises of a company, where a service engineer was injured, even though the explosion actually moved out into the open air. The second occurred in the department store, where an installation contractor was burned because an explosion occurred in a large pressure storage tank in a small room with the result that the explosion was particularly powerful.

At least one person was injured in an explosion at a theatre building. The investigation concluded that the accident has been caused by hydrogen entering the sprinkler room from the sprinkler piping, during maintenance of the building's sprinkler system. Together with indoor air, it formed a flammable mix of hydrogen gas and air. it is known that hydrogen forms in pipes due to corrosion of the pipe internal zinc coating by oxygen and water. The investigation could not identify the exact cause of the ignition.