FWIW dept.

  Over the years, I've accumulated two discharged ~liter- sized fire extinguishers.  In that size, they are cheaper to buy new at the hardware store than to get recharged.    They're aluminum.    Once the pressure is gone, they're safe to cut open.

  Check your old fire extinguishers; is the pressure low?

Dale R.
COZY MkIV #1254
Ch's 4, 5, 9, 16, & 23 in-progress