More big industrial types that are easily recharged or re-inspected.
20-30lbs are about minimum size for anything serious.
They will have an expiration date but yours would fail for surface rust.
If still charged it will be under pressure. Pull the protective cap off (left handed threads) and look at the seal. If its not punctured its still charged.
The extinguisher holds a measured powder type of choice. The charge canister is sealed until you hit the charge lever that punctures the seal that pressurizes the extinguisher and is let out when you squeeze the lever on the end of the hose letting the dry powder escape.
Posts: 18683 | Location: DFW | Registered: December 26, 2008