Self-contained breathing system

1. A breathing apparatus, comprising:

a chassis including a housing defining a breathing reservoir, a first inlet in fluid communication with said breathing reservoir for receiving breathable gas from a self-contained source of breathing gas, a second inlet in fluid communication with said breathing reservoir for receiving ambient air, and a first outlet in fluid communication with said breathing reservoir for delivering breathable gas to a user;

a suction source mounted within said chassis and in fluid communication with said second inlet for drawing ambient air into said breathing reservoir;

a main filter assembly positioned between said second inlet and said breathing reservoir for removing contaminants from the ambient air; and

said chassis adapted to accommodate a plurality of breathing gas container sizes.

2. The breathing apparatus of claim 1 , further comprising:

one or more self-contained sources of breathing gas removably attachable to said chassis for being selectively fluidically coupled to said first inlet; and

optionally, one or more modules are adapted to be interchangeably attached to the chassis in place of one more of said one or more self-contained sources of breathing gas.

3. The breathing apparatus of claim 1 , further comprising:

an air hose for supplying breathable gas to a user, said air hose having a first end adapted to be removably connected to said first outlet and a second end opposite the first end; and

optionally, a face mask adapted to be worn over a user's face and having a connection port adapted to be removably connected to the second end of said air hose.

4. The breathing apparatus of claim 1 , further comprising a port valve for selectively fluidically coupling the breathing reservoir with the first inlet and the second inlet.

5. The breathing apparatus of claim 4 , wherein said port valve is manually movable between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

6. The breathing apparatus of claim 5 , further comprising:

an actuator for activating the suction source when the port valve is in the second position and deactivating the suction source when the port valve is in the first position.

7. The breathing apparatus of claim 4 , wherein said port valve is controlled by an electronically controlled actuator for toggling the port valve between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

8. A breathing apparatus, comprising:

a chassis including a housing defining a breathing reservoir, a first inlet in fluid communication with said breathing reservoir for receiving breathable gas from a self-contained source of breathing gas, a second inlet in fluid communication with said breathing reservoir for receiving ambient air, and a first outlet in fluid communication with said breathing reservoir for delivering breathable gas to a user;

a suction source mounted within said chassis and in fluid communication with said second inlet for drawing ambient air into said breathing reservoir;

a main filter assembly positioned between said second inlet and said breathing reservoir for removing contaminants from the ambient air;

an air hose for supplying breathable gas to a user, said air hose having a first end adapted to be removably connected to said first outlet and a second end opposite the first end;

optionally, a face mask adapted to be worn over a user's face and having a connection port adapted to be removably connected to the second end of said air hose; and

one or both of:

a purge valve connected to the second end of said air hose, the purge valve fluidically connected to a gas pressure regulator and manually actuable to provide a burst of regulated air from the gas pressure regulator; and

an alarm system for providing a user-perceptible alert when a pressure of the self-contained breathing system falls below a preselected value.

9. The breathing apparatus of claim 8 , further comprising:

one or more self-contained sources of breathing gas removably attachable to said chassis for being selectively fluidically coupled to said first inlet; and

optionally, one or more modules are adapted to be interchangeably attached to the chassis in place of one more of said one or more self-contained sources of breathing gas.

10. The breathing apparatus of claim 9 , wherein each of said one or more self-contained sources of breathing gas includes a valve positioned so as to be manually operable by a user when the breathing apparatus is worn by the user.

11. The breathing apparatus of claim 8 , further comprising a port valve for selectively fluidically coupling the breathing reservoir with the first inlet and the second inlet.

12. The breathing apparatus of claim 11 , wherein said port valve is manually movable between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

13. The breathing apparatus of claim 12 , further comprising:

an actuator for activating the suction source when the port valve is in the second position and deactivating the suction source when the port valve is in the first position.

14. The breathing apparatus of claim 11 , wherein said port valve is controlled by an electronically controlled actuator for toggling the port valve between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

15. A breathing apparatus, comprising:

a chassis including a housing defining a breathing reservoir, a first inlet in fluid communication with said breathing reservoir for receiving breathable gas from a self-contained source of breathing gas, a second inlet in fluid communication with said breathing reservoir for receiving ambient air, and a first outlet in fluid communication with said breathing reservoir for delivering breathable gas to a user;

a suction source mounted within said chassis and in fluid communication with said second inlet for drawing ambient air into said breathing reservoir;

a main filter assembly positioned between said second inlet and said breathing reservoir for removing contaminants from the ambient air;

a second outlet for delivering a breathing gas to a user; and

said first and second outlets disposed on opposite sides of a center line of said chassis, said first and second outlets being selectively attachable to an air hose according to the user's preference.

16. The breathing apparatus of claim 15 , further comprising:

one or more self-contained sources of breathing gas removably attachable to said chassis for being selectively fluidically coupled to said first inlet; and

optionally, one or more modules are adapted to be interchangeably attached to the chassis in place of one more of said one or more self-contained sources of breathing gas.

17. The breathing apparatus of claim 15 , further comprising:

an air hose for supplying breathable gas to a user, said air hose having a first end adapted to be removably connected to said first outlet and a second end opposite the first end; and

optionally, a face mask adapted to be worn over a user's face and having a connection port adapted to be removably connected to the second end of said air hose.

18. The breathing apparatus of claim 15 , further comprising a port valve for selectively fluidically coupling the breathing reservoir with the first inlet and the second inlet.

19. The breathing apparatus of claim 18 , wherein said port valve is manually movable between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

20. The breathing apparatus of claim 19 , wherein said port valve is controlled by an electronically controlled actuator for toggling the port valve between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

21. The breathing apparatus of claim 19 , further comprising:

an actuator for activating the suction source when the port valve is in the second position and deactivating the suction source when the port valve is in the first position.

22. A breathing apparatus, comprising:

a chassis including a housing defining a breathing reservoir, a first inlet in fluid communication with said breathing reservoir for receiving breathable gas from a self-contained source of breathing gas, a second inlet in fluid communication with said breathing reservoir for receiving ambient air, and a first outlet in fluid communication with said breathing reservoir for delivering breathable gas to a user;

a suction source mounted within said chassis and in fluid communication with said second inlet for drawing ambient air into said breathing reservoir;

a main filter assembly positioned between said second inlet and said breathing reservoir for removing contaminants from the ambient air; and

a prefilter assembly positioned upstream of the main filter for removing contaminants from said ambient air.

23. The breathing apparatus of claim 22 , wherein the prefilter assembly includes one or more of:

an external filter formed of a woven nylon material;

a mesh filtration medium adapted to filter particles from said ambient air; and

a mesh filtration medium adapted to filter particles having a size of about 10 microns or larger from said ambient air.

24. The breathing apparatus of claim 22 , further comprising:

one or more self-contained sources of breathing gas removably attachable to said chassis for being selectively fluidically coupled to said first inlet; and

optionally, one or more modules are adapted to be interchangeably attached to the chassis in place of one more of said one or more self-contained sources of breathing gas.

25. The breathing apparatus of claim 22 , wherein said main filter assembly is positioned between said second inlet and said suction source.

26. The breathing apparatus of claim 25 , wherein said second inlet is sealed against entry of ambient air when said main filter assembly is not in use.

27. The breathing apparatus of claim 22 , further comprising:

an air hose for supplying breathable gas to a user, said air hose having a first end adapted to be removably connected to said first outlet and a second end opposite the first end; and

optionally, a face mask adapted to be worn over a user's face and having a connection port adapted to be removably connected to the second end of said air hose.

28. The breathing apparatus of claim 22 , further comprising a port valve for selectively fluidically coupling the breathing reservoir with the first inlet and the second inlet.

29. The breathing apparatus of claim 28 , wherein said port valve is manually movable between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

30. The breathing apparatus of claim 29 , wherein said port valve is controlled by an electronically controlled actuator for toggling the port valve between a first position wherein the breathing reservoir is in fluid communication with the first inlet and a second position wherein the breathing reservoir is in flow communication with the second inlet.

31. The breathing apparatus of claim 30 , further comprising:

an actuator for activating the suction source when the port valve is in the second position and deactivating the suction source when the port valve is in the first position.

32. The breathing apparatus of claim 22 , wherein the main filter is selected from a chemical, radiological, or biological filter, or any combination thereof.