Patent ID: 8449661

Claim:
A filter unit comprising: a filter housing; said filter housing having an inner volume and first and second gas connectors respectively configured for connecting said filter housing to a gas conducting passage, said first and second gas connectors communicating with said inner volume and defining a portion of said gas conducting passage that proceeds through said inner volume of said filter housing; a filter in said inner volume of said filter housing, said filter being selected from the group consisting of adsorption filters and absorption filters, said filter consisting of a compressible filter material; a compressing element mounted in said filter housing for movement between a first position and a second position in said inner volume upon exposure to an external force; said compressing element, in said first position, causing said filter material and said compressing element to occupy and entirely fill said inner volume of said filter housing to substantially fill said portion of said gas conducting passage in said inner volume of said filter housing to force gas in said gas conducting passage to pass through said filter material; and said compressing element, in said second position, compressing said filter material to substantially displace said filter material into, and maintain said filter material in a compressed state that is entirely within said inner volume of said filter housing, said filter material in said compressed state causing gas in said gas conducting passage to proceed through said filter housing without interacting with said filter material.