Self-contained breathing system

1. A breathing apparatus comprising:

a chassis defining a passageway for a breathable gas, said chassis further comprising a first inlet for receiving breathable gas from a self-contained source of breathing gas, a second inlet for receiving ambient air, and an outlet for delivering breathable gas to a user;

a suction source coupled to said chassis and in fluid communication with said second inlet, said suction source for drawing ambient air into said passageway;

a main filter assembly in fluid communication with the suction source for removing contaminants from the ambient air;

a breathing hose assembly having a first end removably connected to said outlet and a second end opposite the first end, the second end configured to be removably connected to an external breathing device;

said breathing hose assembly having an inner perforated hose and an outer flexible bag, each extending from the first end to the second end, the inner perforated hose arranged longitudinally within the outer flexible bag, wherein the outer flexible bag is inflatable to hold a volume of air for subsequent delivery to the user;

one or more self-contained sources of breathing gas removably attached to said chassis, wherein each of the one or more self-contained sources of breathing gas is selectively fluidically coupled to said first inlet; and

an alarm system for providing a user-perceptible alert when a pressure in a connected one of the one or more self-contained sources of breathing gas falls below a preselected value, said alarm system comprising a somatic communications system operatively integrated with said breathing apparatus for tactually communicating with a user by producing a vibrational signal responsive to a detected low pressure condition;

wherein said first end of said breathing hose assembly comprises:

a vibrating element mounted within the second end of said breathing hose assembly for producing tactually detectable vibrations;

an electrical connector mounted within the first end of said breathing hose assembly for electrical connection to a power supply within said chassis; and

an electrical conductor passing through said breathing hose assembly for electrically coupling said vibrating element and said electrical connector.

2. The breathing apparatus of claim 1 , wherein the second end of the breathing hose assembly includes a connector element configured for removable attachment to a mating connection port on the external breathing device.

3. The breathing apparatus of claim 2 , wherein the external breathing device comprises a face mask adapted to be worn over a user's face.

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

an outlet valve on said face mask, said outlet valve configured to retain the breathing gas within the face mask when pressure within the face mask is below a preselected threshold value and to allow gas to escape the face mask when pressure within the face mask is greater than or equal to the threshold value.

5. The breathing apparatus of claim 4 , wherein the outlet valve is configured to maintain a pressure within the face mask which is greater than atmospheric pressure.

6. The breathing apparatus of claim 1 , wherein the suction source is mounted within said chassis and the main filter assembly is positioned between said second inlet and said passageway.

7. The breathing apparatus of claim 1 , further comprising a purge valve connected to the first end of the breathing hose assembly, the purge valve actuable to provide a burst of regulated air from the one or more self-contained sources of breathing gas.

8. The breathing apparatus of claim 1 , wherein said electrical conductor passes within said inner perforated hose.

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

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

10. The breathing apparatus of claim 9 , wherein the prefilter includes an external filter formed of a woven nylon material.

11. The breathing apparatus of claim 9 , wherein the prefilter assembly includes a mesh filtration medium adapted to filter particles from said ambient air.

12. The breathing apparatus of claim 1 , wherein the main filter is selected from a chemical, radiological, or biological filter, or any combination thereof.

13. A breathing apparatus comprising:

a chassis defining an passageway for a breathable gas, said chassis further comprising a first inlet for receiving breathable gas from a self-contained source of breathing gas, a second inlet for receiving ambient air, and an outlet for delivering breathable gas to a user;

a suction source coupled to said chassis and in fluid communication with said second inlet, said suction source for drawing ambient air into said passageway;

a main filter assembly in fluid communication with the suction source for removing contaminants from the ambient air;

a breathing hose assembly having a first end removably connected to said outlet and a second end opposite the first end;

said breathing hose assembly having an inner perforated hose extending from the first end of to the second end and an outer flexible bag surrounding the inner perforated hose, the outer flexible bag being inflatable to hold a volume of air for subsequent delivery to the user,

one or more self-contained sources of breathing gas removably attached to said chassis, wherein each of the one or more self-contained sources of breathing gas is selectively fluidically coupled to said first inlet;

an alarm system for providing a user-perceptible alert when a pressure in a connected one of the one or more self-contained sources of breathing system falls below a preselected value, said alarm system comprising somatic communications system operatively integrated with said breathing apparatus for tactually communicating with a user by producing a vibrational signal responsive to a detected low pressure condition;

wherein said first end of said breathing hose assembly comprises:

a vibrating element mounted within the second end of said breathing hose assembly for producing tactually detectable vibrations;

an electrical connector mounted within the first end of said breathing hose assembly for electrical connection to a power supply within said chassis; and

an electrical conductor passing through said breathing hose assembly for electrically coupling said vibrating element and said electrical connector.

14. The breathing apparatus of claim 13 , wherein said electrical conductor passes within said inner perforated hose.