Dual source breathing fluid supply system with alarm

BACKGROUND OF THE INVENTION

This invention relates to a breathing fluid supply system having primary and auxiliary fluid sources, and in par- 25 ticular to a breathing system of this type having a warning device automatically providing an alarm signal when the user inspires from the auxiliary fluid source rather than the normally used primary source.

Breathing fluid supply systems heretofore provided for 30 users working in toxic or oxygen deficient environments are of the portable, self-contained type, or the fixed type adapted for connection to an industrial or other relatively unlimited air supply, or a combination of both. In the latter type, the system is provided with a fluid supply 35 line adapted for connection to a fixed primary air source, usually through a mating connection located in or near the toxic or oxygen deficient environment, and with an auxiliary, self-contained, portable air supply in the form of a cylinder carried on the back of the user. The auxiliary 40 supply is used when the primary supply is disconnected, as when entering and leaving the toxic or oxygen deficient environment, or as an emergency supply in the event the primary supply is interrupted or otherwise impaired.

It is intended that the user continuously inspire from 45 the primary supply during normal use, rather than deplete the auxiliary supply, and that the auxiliary supply automatically cut in to provide air to the user in the event of failure in or disconnection from the primary supply. However, the user normally is not made aware of the transfer 50 from the relatively unlimited primary source to the limited, auxiliary supply, and he may unknowingly deplete his auxiliary supply to a point causing his life to be endangered. While such air cylinders customarily are provided with a pressure gauge, a careless user may forget to check 55 the gauge, particularly when the system is in use.

SUMMARY OF THE INVENTION

Accordingly, a primary object of this invention is to provide a breathing fluid supply system adapted for con- 60 nection to a fixed, primary source and having an auxiliary source automatically operable upon failure of the primary source with an alarm actuated in response to inspiration from the auxiliary source rather than the normally used primary source. 65

Another object of the present invention is to provide a breathing system having the foregoing characteristics and wherein the alarm provides a continuous, audible signal when breathing fluid is being supplied from the auxiliary source. 70

It is also an object of this invention to provide a breathing system having the foregoing characteristics wherein the alarm is automatically de-activated and reset when an adequate fluid supply is established from the primary source.

In one aspect thereof, the breathing system of my invention is characterised by the provision of a face mask, a breathing fluid supply line communicating with the mask and adapted for communication with a primary source of breathing fluid at a first predetermined pressure, an auxiliary source of breathing fluid, a valve normally preventing communication between the auxiliary source and the supply line, a valve control responsive to the fluid supply line pressure and operable automatically at a lower, second predetermined pressure to open the valve and supply fluid from the auxiliary source, and an alarm operable automatically at the lower pressure to signal the utilization of the auxiliary source.

The foregoing and other objects, advantages and characterizing features of a breathing system of this invention are pointed out in the following detailed description of a typical embodiment thereof considered in conjunction with the accompanying drawing depicting the same wherein like numerals represent like parts throughout the various views.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagramatic illustration of a breathing fluid supply system constructed in accordance with the present invention and having parts thereof shown in cross section and other parts in elevation; and

FIG. 2 is a cross sectional view of the alarm used therein, being taken about on line 2—2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, there is illustrated one form of a breathing system constructed in accordance with the principles of the present invention adapted for connection to a relatively low pressure primary breathing fluid source 10, and including a demand valve 11, a high pressure auxiliary breathing fluid cylinder tank 12, an alarm 13, and a pressure regulator 14, all of which (10-14) communicate with a common pressure chamber 15 provided by a suitable housing. Low pressure source 10 can be a common, industrial air supply provided by a compressor or compressed air bottles having a main conduit 16 which would extend into or near the area containing the toxic or oxygen deficient environment. A flexible feeder line 17 is suitably connected at one end to main conduit 16 by means not shown and is adapted at its other end for detachable connection with a flexible conduit 18 communicating with chamber 15, as by a suitably valved quick connect-disconnect coupling 19 of known construction. Demand valve 11, auxiliary supply tank 12, alarm 13, regulator 14, chamber 15 and conduit 18 are adapted to be carried about by a user, being secured to his body by straps or the like, not shown. With this arrangement, the user is limited in movement in the toxic or oxygen deficient environment only by the length of his flexible feeder line 17.

Demand valve 11 can be conventional in construction, comprising a casing 20 having an outlet 21 adapted for detachable connection to a flexible air hose 22 providing a conduit for supplying regulated, low pressure breathing fluid to a face mask, schematically illustrated at M, adapted to be worn by a user of the breathing system. Casing 20 has a tubular boss 23 projecting from a side thereof, boss 23 having an orifice 24 and an annular valve seat 25 therearound against which a valve head 26 seats. Valve head 26 is attached to a valve stem 27 which extends inwardly through orifice 24 to terminate centrally within casing 20 in a ball formation 28 which bears

3,508, 3 against a pressure plate 29 carried by a flexible rubber diaphragm 30. Stem 27 is centered and valve head 26 lightly held against seat 26 by a conical compression spring 31.

Diaphragm 30 extends across casing 20 and has a _gperipheral bead clamped between flange 32 of casing 20 and flange 33 of a casing cover 34. Cover 34 has a plurality of openings 35 exposing the outer face of diaphragm 30 to ambient atmosphere. Outward movement of diaphragm 30 is limited by an adjustable stop 36 carried on cover 34. Demand valve 11 operates in the usual manner in response to inspiration effort of the user which causes diaphragm 30 to move inwardly and tilt stem 27, thereby cocking valve head 26 and cracking open orifice 24 to admit air from low pressure source 10 into face 15 mask M via lines 16 and 17, conduit 18, pressure chamber 15, orifice 24, casing 20 and hose 22. Diaphragm 30 returns against stop 36 as pressure rises in casing 20 with stem 27 following the movement thereof, causing valve head 26 to seat and close orifice 24. 20

Auxiliary air tank 12 comprises the usual portable tank having a limited high pressure air supply. Communication is established with chamber 15 via a conventional control valve illustrated schematically at 38 and a flexible air hose 40. Hose 40 connects with a nipple 41 on 25 chamber 15, the nipple 41 receiving a sleeve 42 terminating in a valve seat 43 within chamber 15. A plunger 44 having a valve head 45 adapted to seat against seat 43 slides through the opposite wall of chamber 15 and the wall of the adjoining regulator 14. ³⁰

Regulator 14 comprises a box-like housing 48 having a central opening 49. The lower end of an upwardly projecting bellows 50 is mounted on top of housing 48 about opening 49. Bellows 50 is centrally recessed to provide a well receiving a spring 51 which engages a pressure plate ³⁵52 at its lower end and a cover 53 at its upper end. Cover 53 is suitably secured to the top of housing 48 and has a plurality of openings 54 permitting ambient pressure to act against the outer surface of bellows 50. Plate 52 ₄θ closes the lower end of the bellows well, thereby closing the bellows across opening 49. A passage 55 communicates between chamber 15 and the chamber 47 in housing 48, whereby the fluid pressure in the two chambers 15, 47 is the same and bellows 50 thereby senses the pressure in chamber 15. 45

Pressure plate 52 connects with the upper end of bellows 50 by means of the wall of the recessed well portion thereof, and has an arm 56 secured to its underside. A rock bar 57 is pivotally connected at one end to the distal end of arm 56 and pivoted adjacent its other end to hous- 50 ing 48 at 58. A right angle leg portion 59 of rock bar 57 bears against the end of plunger 44 to normally maintain the same seated against seat 43 and prevent communication between auxiliary tank 12 and chamber 15, the user normally inspiring solely from the low pressure 55 source 10. The high pressure air in tank 12 acts to slide plunger 44 into following engagement with leg 59 when rock bar 57 pivots leg 59 away from seat 43, thereby admitting regulated air from tank 12 to chamber 15 in response to a predetermined low pressure therein. This 60 occurs when the fluid pressure in chamber 15 drops to a predetermined level, insufficient to overcome spring 51, whereupon the latter moves plate 52 into chamber 47, collapsing bellows 50 and opening valve 45. Air then is admitted to chamber 15 at regulated pressure sufficient 65 to maintain the pressure in chamber 15 at the level for which regulator 14 is set. When the chamber pressure starts to rise above that level, it expands bellows 50 against spring 51 and closes valve 45.

Alarm 13 comprises a bell 61 secured to a valve hous- 70 ing 62 and having an annular skirt portion 63 surrounding housing 62. Housing 62 includes a stepped cylindrical chamber having a plunger member 64 slidable therein. Plunger 64 has an enlarged piston head 65 slidable in an enlarged portion 67 slidable in a reduced portion 68 of 75

542 the stepped chamber and a smaller diameter stem 69 adapted to seat against an annular seat surrounding an orifice 70 through a plate member 71 sealing one end of the stepped chamber. A retainer plug 72 threads into an end of housing 62 to seal the other end of the stepped chamber. A passage 73 communicates between chamber 15 and the stepped chamber (66, 68) and opens through reduced chamber portion 68 into the annular cavity formed between the latter and stem 69. Plunger 64 has an axial passage 74 opening at one end through piston head 65 into enlarged chamber portion 66 and at its other end through a pair or radial openings 75 into the reduced chamber 68 whereby pressure in chamber 15 is transmitted to opposite sides of plunger member 64. It will be noted that plunger 64 has a larger effective area exposed to pressure fluid on the side thereof remote from orifice 70 than on its other side, thereby producing a pressure differential normally maintaining plunger member 64 seated against the seat surrounding orifice 70. A spring 76 around stem 69 engages plate member 70 and a shoulder on intermediate portion 67 of plunger member 64 to bias the latter away from orifice 70, against such pressure differential.

A cup-shaped member 77 having a central opening 78 abuts the outer face of plate member 70 and a retainer 79 threads into the end of housing 62 opposite retainer 72. Retainer 79 has a sleeve 80 which extends inwardly to abut cup-shaped member 77 and maintain the latter in sealing relation to the stepped chamber 66, 68. A piston member 81 slides within sleeve 80 and is biased inwardly by a spring 82 to seat against cup-shaped member 77 and close opening 78. A lateral vent passage 83 opens through sleeve 80 and communicates with ambient pressure through an opening 84 in retainer 79. Lateral passage 83 is normally covered by piston head 85 of piston member 81. The inner end of chamber portion 66, behind piston 65, also is vented, as shown at 85.

To ring bell 61 when the pressure in chamber 15 drops below a predetermined level, spring 76 is selected so that it will overcome a predetermined low differential pressure acting on plunger member 64 and move the latter away from orifice 70. This transmits fluid pressure against a piston head 85 through orifice 70 and opening 84. Piston member 81 is thereby moved outwardly against the bias of spring 82 and strikes skirt portion 63 of bell 61 to provide an audible alarm signal. Piston head 85 simultaneously uncovers lateral exhaust passages, 83, the fluid acting against piston head 85 is exhausted via passage 83 and opening 84 faster than it is replenished via orifice 70, whereupon spring 82 returns piston member 81 to seat against cup-shaped member 77 and cover exhaust passage 83. As long as orifice 70 remains open to the pressure fluid in chamber 15, the fluid pressure acting against piston head 85 will alternately rise and exhaust causing piston member 81 to repeatedly strike bell 61 whereby a continuous audible ringing alarm is sounded.

Once the pressure in chamber 15 rises above the predetermined pressure alarm 13 is automatically reset. This higher pressure acts against the larger area of plunger head 65 to overcome spring 76 and close orifice 71. Spring 82 moves piston member 81 to close opening 78 and, in the absence of pressure transmitted through the now closed orifice 71, piston member 81 is disabled from striking bell 61 until pressure fluid is again transmitted through orifice 71.

During normal use of the present breathing system, air is taken from low pressure source 10 via chamber 15, and into face mask M in the manner hereinbefore described. Assume, for illustrative purposes only, that primary source 10 normally provides air at about 60 p.s.i., that auxiliary source 12 contains air at about 100 p.s.i., or higher, and that regulator A is arranged to crack valve 43 and furnish air from source 12 whenever the pressure in chamber 15 falls below 40 p.s.i. Spring 76 of alarm 13 then is selected so that plunger member 64 is moved to

3,508,542 ⁵ open orifice 70 and ring bell 61 when the pressure in chamber 15 falls below 40 p.s.i. Spring 51 also is selected so that it will pivot rock bar 57 and allow air from auxiliary tank 12 to flow into chamber 15 at regulated pressure in the manner hereinbefore set forth when the pressure in chamber 15 falls below 40 p.s.i.

If the fluid supply from low pressure source 10 is interrupted or becomes insufficient, the pressure in chamber 15 will drop from 60 p.s.i. below 40 p.s.i. whereupon regulator 14 opens valve 45 to admit air from auxiliary source 12 into chamber 15. Simultaneously, alarm 13 is actuated to sound an audible alarm. Air from tank 12 will flow into chamber 15 at a regulated pressure to provide the user with air for limited time, sufficient to at least escape from the toxic environment. However, the pressure in chamber 15, when using auxiliary tank 12, will be maintained at or below the predetermined pressure, for example 40 p.s.i. in the above illustration, since regulator 14 operates to seat plunger 44 against valve seat 43 when this predetermined pressure is attained in chamber 15.

Alarm 13 will thus be continuously sounded in response to pressures in chamber 15 at or below the predetermined pressure or, in other words, in response to unseating of plunger 44 from seat 43 and use of the air from auxiliary tank 12. The user will accordingly be made unmistakably aware that he is drawing air from his limited auxiliary tank 12 and that he has a limited time within which to provide another air supply or to exit from the toxic or oxygen deficient environment. Should the primary source of supply be re-established, raising the pressure in chamber 15 to and above 40 p.s.i., auxiliary source 12 will be closed and the alarm discontinued. All of this is accomplished automatically.

It will thus be apparent that the objects of my invention are fully accomplished in that there is provided a breathing system which continuously sounds an alarm when the user inspires from an auxiliary source rather than the primary source. The alarm moreover is automatically de-activated and reset when the user re-establishes connection with an air supply operating at a pressure above the predetermined pressure at which the auxiliary source is turned on.