One of those ‘it probably won’t happen to you’ situations, but then, they always are:
An old foam-filled fire extinguisher was found among the debris of an engine room which was being prepared for dismantling. When an attempt was made to move the extinguisher it exploded, causing several injuries.
It turned out that the shell of the extinguisher failed because of heavy corrosion – a dnger in any pressure vessel (Yes, including those shaving cream cans).
Fire extinguishers should of course be checked and serviced regularly and you might take a look at extinguishers store in damp or exposed locations.
Check out the original report in MFB15 available at the CHIRPS website.