referring to fig1 and 2 simultaneously , the preferred emergency breathing bag 20 will be described . the preferred breathing bag 20 has an inverted u - shape with two leg portions 22 , 24 and an upper connector 26 joining the leg portions 22 , 24 together . a harness 30 is preferably affixed to the preferred breathing bag 20 , for wearing the emergency breathing bag 20 comfortably , around one &# 39 ; s neck for example with each leg portion 22 , 24 laid downward on the wearer &# 39 ; s torso . the preferred emergency breathing bag 20 contains a reserve of breathable air . this breathable air is passed on to the user by way of an outlet hose 32 connected to a mouthpiece 34 . the outlet hose 32 is connected to the upper connector 26 , at the highest portion of the breathing bag 20 . a cylinder 40 of oxygen under pressure is preferably provided on the emergency breathing bag 20 . this cylinder of oxygen 40 is preferably mounted at an intermediate position along leg portion 24 for example . the preferred cylinder of oxygen 40 has a seal - puncturing operator 42 . this operator is referred to by some manufacturers as an inflator . the preferred inflator 42 is operable by pulling on a handle which is tied to the inflator &# 39 ; s mechanism by a string . the preferred inflator 42 is available from halkey - roberts ™, a manufacturer located in st - petersburg , fla ., usa . the preferred oxygen cylinder 40 can be of any convenient size and pressure . the operator 42 preferably has a low flow rating , or is modified to release oxygen at a low flow . in that respect , a slow flow rate of about 3 . 5 liters per minute is suggested for most emergency applications , but other flow rates may also work depending on the intended use of the emergency breathing bag 20 . the air exhaled by the user is forced from the mouthpiece 34 into an exhaled air hose 50 and into a carbon dioxide absorbing canister 52 . the content of this canister is not provided herein because it is not the focus of the present invention , and it is generally well known in the field of breathing devices . one such supplier of carbon dioxide absorber is micropore inc . located at 350f pencader drive , newark , del ., usa , 19702 . this carbon dioxide absorber is identified under the trademark of extendair ™. the preferred carbon dioxide absorbing canister 52 has an outlet port 54 and a relief valve ( not shown ) on that port . excess pressure buildup on that port is vented outside the bag 20 through the outlet port 54 . excess pressure is defined as slightly above atmospheric pressure . although a carbon dioxide absorbing canister 52 is described herein , a filtering device for filtering and recovering oxygen from carbon dioxide may also be used in the preferred emergency breathing bag 20 . the air inlet hose 32 , the mouthpiece 34 and the exhaled air hose 50 have one or more one - way valves therein to control the flow of air there through . these one - way valves are not illustrated herein and are not described in details because they are not the focus of the present invention . referring particularly to fig2 , the flow path of air inside the emergency breathing bag 20 is illustrated . the cross - hatching or shaded area in fig2 represents the inside region of the emergency breathing bag 20 . the arrows in the cross - hatching represent the flow of gases inside the emergency breathing bag 20 . the oxygen from the pressurized cylinder 40 is released into the leg portion 24 of the emergency breathing bag and accumulates in the upper connector 26 . this oxygen is inhaled by the user through the inlet hose 32 and the mouthpiece 34 . the exhaled air is passed through the exhaled air hose 50 and into the carbon dioxide absorbing canister 52 . the excess exhaled air is expelled through the outlet port 54 and the relief valve of the carbon dioxide absorbing canister 52 . the exhaled air passing through the carbon dioxide absorbing canister 52 , is purified and is forced through a filter 60 and into a t - connector 62 to which is connected two exhaled air distribution hoses 64 , 66 . the purpose of the filter 60 is to remove any particles from the exhaled air , such as crystals forming through the material inside the carbon dioxide absorbing canister 52 . the filtered exhaled air is delivered through the distribution hoses 64 , 66 to the lower compartments 68 of both leg portions 22 , 24 of the emergency breathing bag 20 , below a series of spaced - apart baffles 70 in these lower compartments 68 . these baffles 70 have perforations therein as better seen in fig1 , to let exhaled air migrate upward there through slowly . the baffles 70 are preferably made of a perforated flexible membrane material that is bonded to the walls of each lower compartment 68 . one may also use baffles 70 made of stiff material , supported by spacers extending from the bottom end of each lower compartment 68 . the material of the baffles 70 and the way these baffles are mounted inside the lower compartments 68 are not the focus of the present invention . it is the function of these baffles 70 that is of interest herein . the function of the perforated baffles 70 is to entrap and to retain exhaled air in the lower compartments 68 of both leg portions 22 , 24 as long as possible in a still mode to promote the stratification of the exhaled air . carbon dioxide is heavier than oxygen , and therefore has a tendency to sink and to separate from the oxygen content in the exhaled air . it will be appreciated that means other than a perforated baffle 70 can be used to reduce the turbulence and velocity of the air moving in the lower regions of the breathing bag 20 . it is believed that a series of fins along the side walls of both leg portions 22 , 24 , or a porous , sponge - like material mounted in the lower compartments 68 might also work as good as the perforated baffles 70 . for this reason , the baffles 70 are referred to as baffle means 70 , and the expression should be understood as encompassing all flow - restrictive devices or material to retain air in a still mode in the leg portions of the emergency breathing bag 20 . although three baffles 70 have been illustrated in the drawings , these drawings should not be restrictive . more or less than three baffles 70 can work . similarly , each lower compartment 68 may be longer or shorter than the proportion shown in the drawings . a secondary advantage of the baffles 70 is their ability to dissipate heat generated by the separation of oxygen and carbon dioxide in the carbon dioxide absorbing canister 52 . the breathable air inside the bag 20 is therefore cooler than the air in another breathing bag without baffle . the breathable air inside the emergency breathing bag 20 is also cooler than in other breathing bag because of the fact that portions of the carbon dioxide and heat in exhaled air are released through the relief valve 54 of the carbon dioxide absorbing canister 52 . in use , the emergency breathing bag is worn by a user , and the operator 42 on the oxygen cylinder 40 is activated . oxygen is delivered slowly into the emergency breathing bag 20 , and carbon dioxide is expelled through the relief valve 54 of the carbon dioxide canister 52 at about the same flow rate as the supply of oxygen from the oxygen cylinder 40 and operator 42 . when the oxygen cylinder 40 is empty there should be no more flow through the relief valve 54 . the exhaled air is simply circulated through the mouthpiece 34 , through the carbon dioxide absorbing canister 52 and back into the emergency breathing bag 20 to be re - breathed again . because of the structure of the emergency breathing bag 20 and the baffle means 70 , the exhaled air rising to the upper connector 26 and available for re - breathing has a higher oxygen content than other breathing devices where exhaled air is re - breathed directly . while two leg portions 22 , 24 are illustrated and described herein , it is possible to use only one rectangular bag having a longer vertical dimension , wherein the air rising toward the mouth piece of the breathing device has its carbon dioxide content partly reduced by stratification . similarly , it is possible to used three or more compartments mounted in series to obtain three or more separation phases . it should also be considered that the carbon dioxide absorbing canister 52 is not essential in the preferred breathing bag 20 . for example , one may consider to modify the pillow - shaped breathing bag described and illustrated in applicant &# 39 ; s previous u . s . pat . no . 7 , 047 , 966 , with added baffles and exhaled air distribution hoses to obtain the benefits of separating carbon dioxide from exhaled air in a breathing device . furthermore , it should also be understood that the oxygen cylinder 40 is not essential in the preferred breathing bag 20 . a user of the breathing bag 20 may partly inflate the breathing bag by mouth prior to use , and re - breathe the same air several times . and of course , the harness 30 is not essential for providing no contribution to the purification of the breathable air inside the preferred emergency breathing bag 20 .
the breathing bag has an upper region ; a lower region ; a conduit for delivering exhaled air to the lower region and a conduit for withdrawing breathable air from the upper region . the device also has a baffle mounted therein for entrapping exhaled air in the lower region and for causing the exhaled air to remain in a low turbulence mode , for promoting a separation of oxygen and carbon dioxide from the exhaust air by stratification and for causing carbon dioxide to accumulate in the lower region of the bag . consequently , the breathable air rising from the lower region of the bag has a higher oxygen content . in another aspect of the invention , a method for separating carbon dioxide and oxygen by stratification from exhaled air is also described .