Patent ID: 7213595

Claim:
A filter canister assembly for a gas mask comprising: a primary filter canister with an inlet opening at a first end and an outlet at a second end; a first filter medium adapted to remove aerosols, particulate materials and droplets from air and mounted in the primary filter canister in communication with the primary filter canister inlet opening; a second filter medium adapted to remove toxic gases and arranged in serial communication with the first filter medium in the primary filter canister and with the outlet opening in the first filter housing, whereby the first and second filter media are capable of filtering out contaminants in normal hostile environments; and a supplementary filter canister having an inlet opening at a first end and an outlet opening at a second end, the supplementary filter canister second end is removably mounted to the primary filter canister first end so that the primary filter canister inlet opening is in communication with the supplementary filter canister outlet opening; and a third filter media adapted to filter toxic industrial materials and mounted in said supplementary filter canister in communication with the inlet and outlet openings in the second filter canister.