referring now to the drawing , there is shown in fig1 and 2 an apparatus that comprises a face mask 10 that is adapted to be tightly fitted to the face of the wearer against incursion by the ambient atmosphere ( for clarity , the user is not shown wearing the mask . further for clarity , the alternative mouth and / or nose breathing elements are not shown ). a hose 14 connects the face mask 10 directly to source of breathable air , such as air that has been cleaned and is forced into the face mask by means of a blower motor and fan assembly 15 ( see fig1 , 2 and 6 ). in this embodiment , the face mask 10 is also connected directly to a compressed air bottle 22 via a hose 27 . note that in this embodiment , the face mask itself is the plenum chamber into which bottled air as well as cleaned ambient air are both forced . the blower motor and fan assembly 15 , is operatively connected to a plenum chamber assembly 18 has attached to it a plurality of filter elements 16 . engaging the impeller fan 25 is adapted to cause ambient air to be drawn through the filter elements 16 which may include filters or canisters containing suitable decontamination elements where the ambient air is to be cleaned of solid particulate matter , harmful gases and / or odors to produce cleaned air . subject to the class of canisters fitted and the time spent in the contaminated area , the canisters may provide breathable air in a chemically , biologically or nuclear contaminated environment . the cleaned air , which presumably has sufficient oxygen content , which is adapted to be drawn by the fan 25 into operative relationship with the face mask 10 and thereby provide breathable air to the wearer . the cleaned air can be fed directly to the mask 10 , as shown in fig6 , or it can be deployed to the face mask 10 through a second plenum chamber 21 as shown in fig3 , 4 and 5 . thus , one embodiment of this invention separates the source of cleaned ambient air from the source of bottled air ( suitably supplied from a normal atmosphere ) by providing separate access 30 and 32 to the face mask 10 . each of these separate entry points is suitably adapted to be closed by a valve 34 and 36 which are one way or no return valves . that is , these valves 30 and 32 and the air pressure from the source of air supply for the time being , permit air to flow into the face mask 10 but do not permit the air contents of the face mask to flow out of the face mask back into the alternative source of air supply and purification system . there is also provided a separate valve 38 , that is also a one way valve that allows the contents of the face mask 10 to vent from the face mask 10 to ambient atmosphere . this venting valve 38 is so designed that it only opens when the gaseous contents of the facemask 10 are at a pressure greater than ambient . in other embodiments of this invention , the face mask 10 is connected to a plenum chamber 21 via a hose 14 a . the plenum chamber 21 is adapted to be fed from the air bottle 22 through a hose 27 via a regulator 12 and a shut off valve 24 . the plenum chamber 21 is also adapted to be fed purified air from the filters / decontamination canisters 16 through the fan 25 via hose 29 . the plenum chamber 21 can be fed with bottled air or purified air in the alternative . in fig3 , 4 and 5 the face mask 10 is shown to be connected , via a hose 14 a , to a plenum 21 which in turn , is connected to both a compressed air bottle 22 via a hose 27 . the plenum 21 is also connected , via a hose 29 through the blower impeller 25 , to the plenum chamber 18 , thence to filters / decontamination canisters 16 and on to an ambient air intake 31 . the air bottle 22 is connected to the plenum 21 via a hose 27 , a regulator 12 and a shut off valve 24 . the plenum chamber 21 has suitable valve means 34 and 36 that is adapted to control the flow of air from either the air bottle 22 or the filter / decontamination canisters 16 . the impeller fan 25 provides means for moving ambient air through the intake 31 and through the filter / decontamination canisters into the face mask . the filter / canister plenum chamber 18 supports at least one , and preferably a plurality of filters or canisters 16 . the exit 19 from each canister is preferably operatively associated with the mask plenum 21 so that contaminated air drawn into each filter / decontamination canister 16 by means of the motor driven fan 25 is cleaned and then powered by the fan 25 into the face mask 10 via the hose 14 a and the regulator valving system 21 . in fig1 and 2 here are shown three ( 3 ) canisters 16 each of which contain filter medium . one or more of the canisters can also contain suitable materials that serve to decontaminate the ambient environmental air by eliminating harmful components that are not filterable . the canisters can be assembled , in a preferred embodiment , so that each canister has a separate intake opening 20 and a separate exit 19 . all air passing through any and all specific filter / decontamination canister ( s ) exit into a manifold plenum 18 , having an air collection chamber 33 , that is operatively associated with the fan means 25 as stated above . the individual filter / decontamination canisters can be used individually or in plural configuration and may be fitted all on one side of the filter plenum chamber 18 or fitted some one side and some the other to the desired quantity . a lever handle or rotary handle 43 is connected to filter cover ( s ) 44 and the motor on / off switch 45 . in the semi - automatic or automatic mode the lever 43 can be solenoid operated . in the motor - off position , the filter cover ( s ) is disposed over the air entry port ( s ) of the filter / decontamination canister ( s ) thereby preventing any air from entering the filter / decontamination canister ( s ). this function provides that while the apparatus is operating in a scba mode in a contaminated atmosphere , the filter / decontamination canisters are not taking in any contaminated air and therefore are not becoming unnecessarily contaminated . by being linked to the on / off switch , this ensures that the filter / decontamination canister ( s ) airways are open when the papr is switched on . the air cylinder 22 is assembled into a conventional harness 17 and operatively associated with the papr manifold plenum chamber 21 such that air released from the air cylinder bypasses the filter media in the canisters and proceeds directly to the plenum chamber 21 and thence through the hose 14 a into the face mask 10 . a gas pressure regulator 12 is required for use with the bottled air in order to let the bottle pressure down to a pressure that is manageable by the user . it should be noted that the plenum 21 can be operated in any of three modes . under manual control , starting in papr mode , the papr would be on , the main cylinder 22 valve would be open , the second stage regulator 12 would be closed , the valve 34 in the plenum 21 would be closed and valve 36 would be open due to the pressure of air from the blower motor assembly 15 . when the wearer determines that the atmosphere is in danger of becoming un - breathable or contaminated by a challenge greater than that the filter canisters being worn , are designed to take , the wearer will open the second stage regulator 12 , the resultant air pressure will open valve 34 and air will pass into the plenum 21 . the resultant pressure in the plenum 21 will close the valve 36 shutting off air from the papr . the wearer will now be breathing only bottled air . the wearer will switch off the power supply to the papr blower motor 15 . in semi - automatic or automatic mode , starting in papr mode , the papr would be on , the main cylinder 22 valve would be open , the second stage regulator 12 would be closed , the valve 34 in the plenum 21 would be closed and valve 36 would be open due to the pressure of air from the blower motor assembly 15 . when by means of sensors it is determined that the atmosphere is in danger of becoming un - breathable or contaminated by a challenge greater than that the filter canisters being worn , are designed to take , the system will sound an audible alarm which instructs the wearer to open the second stage regulator 12 , the resultant air pressure will open valve 34 and air will pass into the plenum 21 or , the system will automatically open valve 34 , valve 36 would close and the papr switched off . in fully automatic mode , starting in papr mode the papr would be on , the main cylinder 22 valve would be open , the second stage regulator 12 would be open , the valve 34 would be held closed electrically , or electro - mechanically , in the plenum 21 and valve 36 would be open due to the pressure of air from the blower motor assembly 15 . when by means of sensors it is determined that the atmosphere is in danger of becoming un - breathable or contaminated by a challenge greater than that the filter canisters being worn , are designed to take , the system will switch the control to valve 34 which would then open , and air will pass into the plenum 21 closing valve 36 and then the papr would be switched off .
a combination of an scba system for providing bottled air to a user and a papr system for purifying ambient air for use by a user wherein the two systems are used alternatingly depending on the contaminated condition of the ambient air and the oxygen content of the ambient air .