Breathing apparatus

Claim 1

A breathing apparatus comprising: breathing means for permitting a user to inhale a breathable gaseous medium and exhale gases; first conduit means connected at one end to said breathing means to establish a flow path for the breathable gaseous medium to be passed to a user for inhalation; second conduit means having one end connected to said breathing means to establish a flow path for the exhaled gases; regeneration means operatively coupled to the other ends of said first and second conduit means and in fluid communication therewith for accepting and regenerating said exhaled gases from said second conduit means so that breathable gaseous medium is discharged into said first conduit means; and cooling means downstream of said regeneration means for cooling said breathable medium, said cooling means including (a) a reservoir containing a predetermined volume of refrigerant liquid, a portion of said first conduit means being disposed in said reservoir in heat-exchange relationship with said refrigerant liquid, and (b) manually operable pressure relief valve means establishing fluid communication between said reservoir and the ambient environment, said valve means for permitting manual selection of a predetermined vapor pressure for the liquid refrigerant and to responsively control the temperature of the liquid refrigerant and thus the temperature of the breathable medium flowing through said first conduit means in heat-exchange relationship with said liquid refrigerant, wherein said valve means includes: (i) a valve body defining a valve seat; (ii) valve stem means in seated relationship against said valve seat to thus prevent fluid communication between said liquid refrigerant and said ambient environment when said liquid refrigerant exhibits a vapor pressure below said predetermined pressure yet is movable into spaced relationship with said valve seat to establish fluid communication between said liquid refrigerant and said ambient environment; and (iii) adjustable coupling means for coupling said valve stem means and said valve body, said coupling means for adjustably determining movement of said valve stem means from said seated relationship to said spaced relationship relative to said valve seat to thereby responsively permit selection of said predetermined vapor pressure of said liquid refrigerant.