US3158153A

US3158153A - Passenger mask assembly

Info

Publication number: US3158153A
Authority: US
Inventors: Bloom Aaron; Orland W Wilcox
Original assignee: Sierra Engineering Co
Current assignee: TEXACE Corp A CORP OF TEX; Scott Technologies Inc
Priority date: 1959-06-15
Filing date: 1959-06-15
Publication date: 1964-11-24
Anticipated expiration: 1981-11-24
Also published as: GB931363A

Description

Nov. 24, 1964 A. BLooM ETAL 3,158,153

' PASSENGER MASK ASSEMBLY Filed June 15, 195s 456 5 Il' 55 3 l a Zr Hmm/v E400/14 Jim/va /44 lI//zmx INVENToRs. l )j BY% United States Patent O 3,158,153 PASSENGER MASK ASSEMBLY Aaron Bloom, Pasadena, and (irland W. Wilcox, Sierra Madre, Calif., assignors to Sierra Engineering Company, Sierra Madre, Cali., a corporation of California Filed `inne l5, 3.95%, Ser. No. 826,259 8 Ciaims. (Ci. tze-ddr2) The invention relates to breathing equipment andhas special reference to an exceptionally light-weight breathing mask containing a mechanism such that it is capable of diluting a supplemental oxygen supply with ambient air and passing it to the subject by use of an extremely light-weight piece of equipment which is comfortable to wear and which is so light in weight that there is no appreciable weight penalty in connection with its use.

When the need arises for oxygen at high altitudes, the rst need is for a relatively high concentration of oxygen winch, however, should not persist for an indefinite length of time. Although special types of breathing equipment' have been developed heretofore intended by some adjustment or other to take care of these needs, the equipment has been somewhat complicated, expensive and heavy and, as a consequence, not readily suited to infrequent application to a subject nor to subjects unaccustomed to the use of such equipment.

Those masks heretofore made use of to a larve degree have been provided with a contoured edge presumably of such shape as to tit the irregularities of the face, but because of this the masks must be worked out in many different shapes and sizes because ot being not sutciently exible to adapt to the many diierent shapes and sizes of faces encountered.

In other respects, also, the available breathing equipment is relatively heavy and must not only be securely strapped to the helmet or to the face of the subject, but must incorporate in the fastening means expedients for adjustments to accommodate different conditions and to improve the comfort of the mask on the face in positions wherein it must be worn for many hours of continuous use. Masks for use by the crews of aircraft, moreover, are those which can more readily be used by persons of long experience in the use and handling of such equipment, and are of such type that they have not bee readily adaptable to use by passengers who may have occasion to take advantage of the mask only on very few occasions and then without benefit of instruction with respect to how the mask should be placed on the face and thereafter made use of.

It is therefore among the objects of the invention to provide a new and improved breathing mask equipped with a dilutor valve in series with the inhalation check valve whereby to assure iirst a supply of oxygen of relatively high concentration followed by the automatic addition of ambient air which takes place as the subject continues to breathe.

Another object of the invention is to provide a new and improved breathing attachment equipped with a composite light-weight valving mechanism so constructed that the inhalation and exhalation check valves are constructed in a unitary assembly with an ambient air checkl valve whereby to produce a compact light-weight and etiicient valving mechanism.

Still another object of the invention is to provide a new and improved breathing mask which is of such construction that it can be fitted comfortably to virtually any face without need for adjustment. Y

Another object of the invention is to provide a new and improved breathing mask which is exceptionally light in weight so that when the occasion comes for applying it to the face, it can be lifted and held to the face without special experience being needed on the part of the subject, and with relatively little ei'fort due to the ease of adjustability by mere pressure and the light-weight construction of the device.

Still another object of the invention is to provide a new and improved breathing mask of simple light-weight design especially suited to use by inexperienced passengers in high altitude iiight which automatically mixes ambient air with a supply of oxygen while the subject is inhaling thereby to enable supplying of passengers with a proper amount of oxygen from a common source without the necessity of expensive tubing, duct work andl valves.

A further object of the invention is to provide a new and improved light-weight breathing mask of such versatility that it can be quickly adjusted to the face of any subject, which is of such design that it can be hung in a readily accessible place within easy reachv when needed, and whichby reason of its design and construction, is relatively tamperproof. v

Still further among the objects of the invention is to provide a new and improved light-weight breathing mask designed for construction of particularly inexpensive materials and one wherein small light-weight parts can be made with a virtually maximum degree of uniformity, and which moreover necessitates relatively few separate parts without, however, impairing the provision of an extremely reliable breathing mask.

With these and other objects in view, the invention consists of the construction, arrangement and combination of the various parts ot the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims, and illustrated in the accompanying drawings. f

In the drawings: Y

FGURE 1 is an elevational view ofthe breathing mask assembly partially broken away and in the position it would occupy when suspended above the passenger seat.

FIGURE 2 is a cross-sectional view taken on the line 2 2 of FIGURE 1.

FIGURE 3 is a partial longitudinal sectional view taken on the line 3 3 of FIG. 2 showing the valve positions during inhalation.

FIGURE 4 is a fragmentary longitudinal sectional view showing valve positions during exhalation.V in the embodiment of the invention chosen for the purpose of illustration there is shown an oxygen supply line l@ at the end of which is a shut-off valve ii from which extends a length of flexible tubing l2. The tubing extends into a iiexible bag l which will ultimately serve as a reservoir of oxygen supplied to it through the tubing. At the lower end of the bag, as viewed in FIGURE l, is a facev receptacle i4, a beveled rim 15 of which is adapted to be pressed against the face of a subject surrounding the mouth and nose. lt should be understood that the receptacle is of very light weight synthetic plastic so that a wall 16 thereof, the beveled rim l5, and a bottom 17 may be bent and ilexed freely so as to press the rim continuously throughout its perimeter against the varying contours ot the face of the subject without any adjustment being needed other than mere pressure against the face. i

inasmuch as pure oxygen will customarily be supplied through the supply line lil to the bag 13, most conditions under which the mask will be used require a mixing of the oxygen with ambient air which would be present in the cabin of an airplane. Consequently, there is provided a composite valve device Ztl between alower end 2l of the bag 13 and the face receptacle 14 which facilitates the mixing of oxygen and ambient air during inhalation by the subject, and which, by the functioning of suitlable outtlow check valves, shuts off the supply of oxygen and ambient air during exhalation and facilitates the exhaust of air from the subject.

The composite valve device is one constructed primarily of synthetic plastic materials in the interest of preserving a very ht weight construction of carefully iitted parts and in the interest of the supply of large quantities at a moderate price.

In order to secure the composite valve device to the bottom 17 of the face receptacle i4, there is provided a substantially annular inner plate 22 which underlies the bottom 17 at a location within the face receptacle 14. The inner plate has an upper :surtace 2,3v which presses against the underside of a thickened rim 24 which, together with an annular lip 25, defines an opening 26 through the bottom of the face receptacle. Bosses 27 on the inner plate extend through appropriate holes Z in order to improve the means of attachment and sealing eiect.

On the opposite side of the bottom 17 is an outer plate 29 which includes an annular portion 3i) located` immediately opposite the inner annular plate 22. so that these two elements can be pressed against opposite sides of the thickened rim 24 when assembled, `thereby to produce a properly sealed attachment. The outer plate, moreover, includes spokes 31 which extend radially outwardly and carry a pair of concentric stiffening rings 32 and 33 joined together by intermediate spokes 34. The outermost ring 33 is substantially coincident with the corner where the bottom 17 joins the side wall 16 and thereby provides a stiiening me-ans for the bottom portion of the face receptacle. Moreover, the annular portion Sil, the rim 2d and the inner plate 22 may be considered as comprising a reinforcement for the opening through the bottom.

An outer face 35 of the annular portion 36 serves as a valve seat at the inside perimeter at the location indicated by the reference character 36.

A valve body 46 a has tting 41 thereon at the upper side which receives outer and inner plastic rings d2 and 43, respectively, at a neck 44 of the bag whereby to anchor the bag to the body witha gas tight joint. The body may be described as defining a chamber 45. To mount the body at a location spaced from the outer plate 29 and its annular portion 30, there is provided a spacer ring indicated generally by the reference character 46, the spacer ring cornprising an annular ring element 47 and legs 48'. On the body, also, are bosses 49, and screws Si) extend through the bosses, the legs 4S, the annular portion 30, and threadedly into the inner plate 22 whereby to secure all parts together in assembled position.

Within the body is a relatively thin substantially cylindrical valve element 55, the cylindrical wall of which is adapted to press against an interior cylindrical wall 56 of the chamber 45. The cylindrical valve element has a at flange 57 thereon which extends outwardly to a position against the lower side of the body. Spaces 58 intermediate the bosses 49 and an annular lower rim 59 ofthe valve body provide for the ingress of ambient air to the chamber 45 when the cylindrical valve ele-ment is unseated. The valve element 55, therefore, permits inflow of air, but serves as a check in the respective inflow passageways when the pressure is reversed.

A composite valve member indicated generally by the reference character 60 consists of a plate 61 which extends outwardly to a position overlying the valve seat 36 which is a portion of the upper face 35 ofthe outer plate 29. An upwardly extending rim 62 of the composite valve member provides means for attachment of a thick ened edge 63 of an annular flexible sealing connection 64, an outer at portion 65 of which is contained between the annular ring element 47 and the annular rim 59 ofthe body. The presence of the sealing connection provides a oating connection and mounting for the composite valve member 60. Attention is also directed to the fact that as a matter of economy and convenience the same ring l i element 4:7 may be employed to jointly attach both the flexible sealing connection 64 `and the cylindrical valve element S5 to the rim 59 in operating position.

In the composite valve member 6@ are supply passages 66 which communicate between the chamber 45 and the interior of the face receptacle. To close the supply passages there is provided an inflow check valve element 67 which comprises a stem 63 anchored to the mid-portion of the composite valve member 60 and a disc 69, a rim 70 of which makes contact with a lower face 71 of the composite valve member 6?. The disc 69 may be one of a type provided with a flexible annular inner portion 72 which permits the entire disc to lift from its seat without the necessity of any movement in the stem 68.

A spider comprising legs 73 intersecting at a mid-point serves to stiften the inner plate 22- and provides a space 74 within which the outiiow check valve 67- can operate eiectively.

When installed, the face receptacle 14, the bag 13, and the flexible tubing 12 may, ifdesired, be compacted to-` gether and stored in a suitable box or receptacle, notshown which in tact frequently forms part of the luggage rack immediately above each passenger seat. When there is a demand for supplying oxygen by use of the mask, it is necessary only for the subject to grasp the face receptacle 14 and draw it downwardly toward himself until he is able to place the beveled rim 15 against his face in the area surrounding his nose and mouth and there press it snugly into contact. The motion of drawing the face receptacle downwardly is made use of in opening the valve 11, inasmuch as oxygen is supplied from a common supply through the supply line 1 0 which is employed as a means of regulating the amount of oxygen available to each of the individual masks from some common control. To elect an opening of the valve 11; without jeopardizing the connections or adjustment of the passenger mask, a special precaution is made use of whichV comprises a'cord 75 which is firmly secured bya loop '76 andfastening 77 to a bar 78 which is an integral por-tion of the valve body di). The opposite end of the cord is provided with a loop 79 which extends through one of the holes 80 in a portion 81 of the exible tubing 12 which extends into the interior of the bag 13. Although the bag itself may be of very thin Walled material, the ilexible tubing is relatively heavy walled and of sufficient tensile strength to make it safe to use as an extension of the cord. A collar 82 anchored to an upper portion of the iiexible tubing has a cord 83 attached thereto, and connected to the cord SS-is a but-ton 84 contained Within a fork 85 of a valve handle 86 so that by. pulling upon the face receptacle a pull `is exerted through the cord 75,`the flexible tubing 12 and cord 83 upon the handle S6 of the valve which-turns on the valve so that oxygen will ow through the valve and ilexible tubing into the bag 13. If the` pulll on the cord is too great, the button 34 will merely pull out of the fork 85 so 4that no damage will result.

By providing a reservoir of oxygen in the flexible bag 13, an immediate supply of oxygen will be available in quantity adapted to achieve successful operation of the valving mechanism. It will be understood that there is a continuous supply of oxygen to the. reservoir regulated by a common control in the airplane suicient to replenish the supply in the reservoir or bag 13 as it becomes used during the breathing cycle.

When fthe subject rst inhales, due to the fact that the pressure inside the bag is; greater than the pressure of ambient ai-r, the first gas fed to the subject through the passages 66 will be oxygen or" the concentration present in the reservoir. This is a most useful pontion ofi the cycle because by introducing oxygen inthe first part of the inhalation cycle through the lungs, the subject is assured of a higher concentration of oxygen in the alveolar sacks which in turn transmits ythe oxygen to the arterial blood flow and maintains a maximum level of oxygen arterial saturation.

As soon as the oxygen in the reservoir bag has been depleted, the ambient air inflow check valve will open. This valve will not open prior to depletion of the reservoir supply because of the higher differential pressure across the ambient air iniiow check valve. That is to say, the pressure on the inside of the cylindrical part of the valving assembly is higher than on the outside during the lirst part of the inhalation cycle or inspiratory process. As soon as inhalation reaches a certain level depleting the oxygen supply in the bag, fthen the infiow check valve for ambient air will open and the subject will then lill his lungs with ambient lfair and to some extent with oxygen which continues to be supplied to the bag through the tubing 12. The last phase of the inhalation cycle will fill the subjects lungs and distend Ithem to the normal extent.

Thereafter upon exhaling, both of the inflow check -valves are closed and the outflow check valve in the exhaust passage opens, permitting free discharge of exhaust gases from the lungs.

Attention is called to the very thin wallof the cylindrical valve element 55 which when flexed inwardly permits an ample low of air Vthrough the spaces 58. This same circumstance assists in closing this panticular valve under a slight pressure differential when inhalation of a high concentration of oxygen is needed.

During this portion of the cycle, the valve member e@ is in the position shown in FIG. 3 with its annular plate portion 61 seating upon the valve seat 36 of the outer plate 29.

Since there is very little resistance to aspira-tion supplied by the pressure of oxygen Within the reservoir 13, the composite valve member 60 is readily lifted, lifting the valve element 60 from the plate 29 around its entire perimeter, thereby permitting a free outflow of exhaust gases through the exhaust gas spaces 87 of the housing. Also when exhalation takes place the check valve 67 is seated.

When necessity for oxygen ceases, the face receptacle is merely removed from the face and the inflow check valve 67 and cylindrical valve 55 will normally reseat. The valve 11 can ultimately be turned to shut-olf position manually.

As a further indication of the lightness and compactness hereinabove described, it will be understood 'that the cylindrical valve element 55 has a wall thickness in practice of approximately .007 inch, and that the flexible walls of the face receptacle are constructed preferably of rubber like material in -thickness of about .015 inch. Those exible sections within the valve device exemplified by the sealing connection 64 and the portion 72 of the valves 67 may be as thin as .003 inch. Virtually no metal parts comprise the valve device except the screws Sti. All of the remaining parts may preferably be constructed of light weight synthetic plastic, thereby to provide a valve structure extremely light in weight and accurate with respect to the tit of the several parts. In practice it has been found that the entire mask assembly inclusive of the face receptacle, composite valve device, the bag, and appropriate flexible tubing may be as light as 21/2 ounces. The device thus described is particularly well adapted to aircraft travel, and due to its simplicity in operation, is especially effective for use by persons inexperienced with conventional breathing equipment.

Although we have herein shown and described our invention in what we have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of our invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent structures and devices.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A breathing mask assembly for passing sequentially breathing gases from a selected source to a subject comprising a face receptacle, means forming a passage therethrough, la reinforcement around said passage comprising a plate retained in sealing engagement with the receptacle around the edge of said passage and having a passageway therethrough, said reinforcement having an outwardly facing exhaust valve seat thereon, a valve body secured to said reinforcement and having a chamber therein, exhaust gas passage means between said exhaust valve seat and the exterior, a composite valve member comprising an exhaust valve element `adapted to seat on said outwardly facing exhaust valve seat, means forming a mixed gas supply passage through said composite valve member in communication between said chamber and said passage- Way, and an iniiow check valve element normally closing said mixed gas supply passage, a movable sealed conneotion between said composite Valve member and said body, said chamber having an unobstructed opening, a flexible reservoir bag attached to said body with the interior of said bag being in constant open communication with said chamber through said unobstructed opening and said chamber providing yan unobstructed path forrgases from said bag rto said mixed gas supply passage, a exible supply tube connecting said bag with said source, an arcuate interior wall for said chamber, means forming auxiliary passage means for ambient air through said interior wall between the exterior and said chamber on the upstream side of said inflow check valve, a flexible relatively' thin substantially arcuate valve element normally closing said auxiliary passage means, said arcuate valve element being subject to exure to open -position to admit'ambient air to said chamber during the inhaling cycle of the subject, said arcuate valve element and said inliow check valve being shiftable to closed positions and said exhaust valve element being shiftable to open position during exhaling cycle of the subject.

2. A breathing mask assembly for passing sequentially breathing gases from a selected source to a subject comprising a face receptacle, means forming :a passage therethrough and a reinforcement around said passage comprising an annular plate retained in sealing engagement with the receptacle around said passage and having a passageway therethrough, said reinforcement having an annular outwardly facing exhaust valve seat, an annular valve body secured to said reinforcement and having a chamber therein, a composite valve member comprising an exhaust valve element adapted to seat on said outwardly facing exhaust valve seat and exhaust passage means between said valve seat and the exterior, means forming a mixed gas supply passage through said composite Valve member and an inflow check valve element on said composite valve member normally closing said mixed gas supply passage, a movable sealed connection between v said composite valve member and said body, said chamber being in constant communication between said mixed gas supply passage and said source of gas, a cylindrical interior wall for said chamber, auxiliary passage means for ambient air through said cylindrical interior wall between the exterior and said chamber and on the upstream side of said inflow check valve, a relatively thin substantially cylindrical Valve element normally closing said auxiliary passage means, said cylindrical valve element being subject to flexure to open position tto admit ambient air Ito said chamber and said gas supply passage during the inhalingcycle of the subject, said cylindrical valve element and said inflow check valve lbeing shiftable i to closed positions and said annular valve element being shiftable to open subject.

3. A breathing mask assembly for passing sequentially breathing gases to a subject comprising a iiexible walled face receptacle, means forming a gas passage through the said receptacle, a multiple Valve member having a passageway therethrough adapted to communicate with said gas position during exhaling cycle of the passageV and an annular outwardly facingL exhaust valve seat surrounding saidpassageway,A a, valve body on said receptacle and spaced means separating said body from the receptacle at a-location surrounding said passageway and.V forming exhaust passage means therebetween, said multiple valve .me mber having annular valve element reciprocably mounted therein at a location adapted to engage said exhaust valve seat and having` a mixed. gas supply passage therethrough, any iniiow` check` valve for, saidmixed gas. supplyl passage, a chamber in said body, means forming ambient. air passage means through said body to said chamber on; the upstream side of said inflow check valve and inow. check valvey means for said ambient air passage means-,- a lCXble compensator bag attached to said body andin constant communication with the mixed gas supply passage, and ai flexible supply tube connected; to saidbag.

4. A mask assembly cvornprising.- a breathing attachment for the face ofY- a subject, aiiexible reservoir bag, a iiexible tube connecting said reservoir bag with an oxygen supply line having a control Valve therein, a diluter valve device connecting, saidv reservoir bag, with saidl breathing attachment, saiddiluter valve device comprising a valve4 housing-on said. attachment having a pas.- sage therethrough in communication respectively between saidreservoir and'said attachment, an iniiowfcheck valve in saidpassage, said housing having an ambientair pas,- sage formed therein fon-admittingair from outside the device into said rsit passage, said ambient airv passage being disposed on the, upstream side of` said i'niiowA check valve, av second inflow check valve in said ambient air passage, said housing having an exhaust, gas4 passage formedA therein between the attachment; and-the ambient air passage, said exhaust gas. passage beingon the-down.- stream side. ofl said inflow checkf valve, andV an outlijow check valve in saidexhaust passage and means connect.- ing said iiexible tubeand said controlfvalve for activating said contro1-valve tosupply oxygen through said tube to said bag. in responsefto .apull onA said .tube.

5. A diluter. valve. device comprising avalve mounting structureiincluding a` valve housing having an upstream end andi-a downstream end'fand apassageextending therethrough; to andI between said' ends, saidpassage comp-rising an inflow section at the upstream; end, an outliow section at the downstream. end and a; mixersection: intermediate, said'infiowl and outflow sections,` anda freely moving. inow check valve in said; passage at the down stream end thereof, said housing having an ambient air passage for admitting air from outside the device into said first passage, said ambient air passage being located on. the upstream side otrsaid iniiow check valve and; in communication between.. the. mixer sectionK and the exterior, said. housing having ai second; inow check valve in the ambient air passage, the portion of -said passage between the iniiow section andA the downstream side of said second. inflow checky valve being. open under all conditions of operation of said diluter valve device, the portion of said passage between the downstream side of the second inflow check valve-.andthe-rstinflow check valve being open under all conditions :of operationof said diluter valve device, saidtsecond inflow checlevalve comprising a freelyy moving valve elementand an. exhaust: gaspassage throughsaid mountingstrueture having an outflow. check valve therein.

6. A diluter valve.device-.comprisingavalve mounting structure including; a valve housing: having an upstream end and a downstreamendaand apassage .extending therethroughto and between said ends, a. freely moving iniiow check valve in said passage at the .downstreamendthereoi said housing having an ambient air passage including a substantially concentric` cylindricalV ambient air valve seat extending around the circumference of said body for admitting air from outside the device into said' first passage, said ambient air passage being located on the upstream side. of said iniiow check valve, said housing having a second inflow check valve in the ambient air passage. said second inow check valve comprisinga freely moving substantially cylindrical flexible resilient valve element having. one end. thereof sealedi in said housing adjacent` the ambient air passage andthe other end thereof resiliently impressed. into engagement with said ambient air valve seat, and an exhaust gas passage throughsaid mounting structure having an outflow check valve therein.

7. A diluter valve device comprisinga valve mounting structurel including5 a valve housing having. an upstream end and a downstream end and' a passage extending'therethrough to and between said ends, an axially movable supporting member in said housing including atransverse plate, a freely moving inflow check valve device in said passage at the downstream endthereof and mounted on said plate, a rim intermediate said upstream and downstream ends of said housingy and a flexible sealing connection betweenl said plate and .said rim', saidhousing having an ambient air passage including a substantially concentric cylindricalambient air valve seat extending around theA circumference ofsaid body for admitting air from outside the device into. said iirst passage, said ambient air passage being located on, Athe upstream side of said inflow check valve. and on the upstream side of said rim, said housingy having a second. inflow check valve in the ambient air passage, saidsecond inflow check valve comprising a freely moving substantially cylindrical' iiexible resilient valve element having one end thereof sealed upon said' rimadjacent the ambient air passage, the other end of said resilient valveelement being resiliently impressed into engagement with; said ambient air valve seat, and an exhaust gas passagefthrough saidmounting-structure havingan outflow check valve therein.

8. A passenger mask assembly comprising a maskv member includinga wall and a diluter valve device supported on said wall, said wall having an aperture therethrough and a thickenedrim around the edge of said aperture, said valve device comprising a. valve body having an up stream end, a downstream end'and a supply passage between said ends, a separate rim forming partofsaidL-'valve body adjacent said wall, an inner plater on the inside of said wall having'an aperuiretherethrough, an outer plate on the outsideV of said Wall having,V an aperture therethrough in communication with said last identiedv aperture and said supply passage, an axially moving support ing member in said supply passage having a flexible conneotionto the valve body adiacentl said separate rimand having an inflow check valve device mounted thereon, said thickened rim comprisingvalve seat means forming an annular exhaust valve seat around the aperture in said wall, a plate on said supporting member comprising an exhaust valve element adaptedto seat on said seat; and a common anchoring means securing said inner and outer plates in assembledrelationship with saidY valve body and the portion of said wall and the thickened rim thereon iormingsaid valveseatmeans.

References Cited in the le of this patentl UNITED STATES PATENTS 2,820,469 Seeler Jan. 29, 1958 2,843,119 Glasser July. 15, 1958 2,392,456 Seeler lune 30, 1959 2,894,507 Seeler July 14,1959

2,942,602 Seeler lune. 28., 1960 FOREIGN.- PATENTS 564,032 Germany Nov, 12, 1932

Claims

3. A BREATHING MASK ASSEMBLY FOR PASSING SEQUENTIALLY BREATHING GASES TO A SUBJECT COMPRISING A FLEXIBLE WALLED FACE RECEPTACLE, MEANS FORMING A GAS PASSAGE THROUGH THE SAID RECEPTACLE, A MULTIPLE VALVE MEMBER HAVING A PASSAGEWAY THERETHROUGH ADAPTED TO COMMUNICATE WITH SAID GAS PASSAGE AND AN ANNULAR OUTWARDLY FACING EXHAUST VALVE SEAT SURROUNDING SAID PASSAGEWAY, A VALVE BODY ON SAID RECEPTACLE AND SPACED MEANS SEPARATING SAID BODY FROM THE RECEPTACLE AT A LOCATION SURROUNDING SAID PASSAGEWAY AND FORMING EXHAUST PASSAGE MEANS THEREBETWEEN, SAID MULTIPLE VALVE MEMBER HAVING AN ANNULAR VALVE ELEMENT RECIPROCABLY MOUNTED THEREIN AT A LOCATION ADAPTED TO ENGAGE SAID EXHAUST VALVE SEAT AND HAVING A MIXED GAS SUPPLY PASSAGE THERETHROUGH, AN INFLOW CHECK VALVE FOR SAID MIXED GAS SUPPLY PASSAGE, A CHAMBER IN SAID BODY,