US2855923A

US2855923A - Breathable gas regulating apparatus

Info

Publication number: US2855923A
Application number: US378856A
Authority: US
Inventors: Kimes Robert; Robert L Kesler; Stanley J Mitchell
Original assignee: Garrett Corp
Current assignee: Garrett Corp
Priority date: 1953-09-08
Filing date: 1953-09-08
Publication date: 1958-10-14
Anticipated expiration: 1975-10-14

Description

ct. 14, 1958 R. KIMES ETAL A 2,855,923

BREATHABLE GAS REGULATING APPARATUS Filed Sept. 8, 1953 3 Sheets-Sheet 1 IO w 0's 2 RUBERT muss, ROBERT L. KESLER,

STANLE'YJ. MITCHELL,

INVENTORS.

x BY 4 Oct. 14, 1958 R. K!MES ETAL BREATHABLE GAS REGULATING APPARATUS 3 Sheets-Sheet 5 Filed Sept. 8, 1953 F/ga.

.U W I 2 7 w 4 n J 0 6 0 z n a I a M w =1 M T I mm 8 M. 0S 0% M v MP w V! l n M ww M n l s L 0 0 M w M 0 0 w I m m I w a A w R. 0 2 9- a v 4 a 2 02 e 5 7 v5.5 MB $33 o2 Eb: AS 333 Fig.7

I400 I200 I000 800 600 400 200 SUPPLY PRESSURE ROBERT K/MES ROBERT L. KELER, STANLEY .1. MITCHELL,

- INVENTORS.

United States Patent 2,855,923 BREATHABLE GAS REGULATING Ai PARATU's Robert Kimes, Culver City, Robert L. Kesler, Pacific Palisades, and Stanley J. Mitchell, Los Angeles, Calif., assignors to The Garrett Corporation, Los Angeles, Calif., a corporation of California Application September 8, 1953', Serial No. 378,856

21 Claims. (Cl. 128142) The present invention relates generally to breathing apparatus and relates more specifically to apparatus enabling the user to breathe both above and beneath the surface of water, in poisonous atmospheres, at high altitudes, suitable for use in emergency resuscitation.

Heretofore, breathing apparatuses designed for use in situations similar to those for which the present device is to be used have had inherent inadequacies such as, for example, uncomfortable or prohibitive resistance to breathing, a steady increase in such resistance as the breathable gas supply was exhausted, dangerous conditions resulting from apparatus failure and failure to provide sufiicient warning to the user of the approach of exhaustion of the breathable gas supply. Additionally, prior devices have often been extremely heavy, cumbersome and difiicult to maintain in operating condition and adjust for optimum performance. Furthermore, a considerable amount of re-breathing of exhalation products has occurred in prior devices of this character, such re-breathing being often harmful from a physiological standpoint.

Accordingly, it is an important object of the present invention to provide breathing apparatus which will overcome the beforementioned ditficulties experienced in connection with prior breathing devices.

It is another important object of the present invention to provide a unitary, light weight, reliable, and efficient breathing apparatus wherein the breathing resistance is maintained at a substantially constant, low level throughout the entire useful period during which compressed breathable gas of varying pressure is utilized.

A further object of the present invention is to provide a breathing apparatus of the type described, wherein sub-. stantially n mixing of fresh breathable gas with exhalation products occurs.

A still further object of the present invention is to provide a breathing apparatus wherein means are provided to interrupt the flow of breathable gas from a source when the gas source approaches exhaustion, thereby to warn the user of the limited gas supply still available and to permit manual operation of a suitable valve for admitting the balance of the breathable gas to the breathing apparatus, thus providing an additional period of use during which time the user may seek a breathable ambient atmosphere.

It is another object of the present invention to provide a check valve arrangement for conducting exhalation products to ambient atmosphere, means being provided to prevent inadvertent reverse gas flow due to surging of the ambient medium, such as liquid or the like, and for preventing admission of such ambient medium to the respiration system of the user.

Other and further important objects of the present invention will become apparent from the disclosures in the following detailed description, appended claims and accompanying drawings, wherein:

2,855,923 Patented Oct. 14, 1958 ice Fig: 1 is a transverse sectional view of the breathing apparatus of the present invention;

Fig. 2 is an enlarged fragmentary sectional view showing the regulating mechanism in the position assumed during inhalation;

Fig. 3 is a sectional View showing portions of the gas reserve valve and taken substantially as indicated on line 33 Fig. 2; p

Fig. 4 is a fragmentary sectional view showing portions of the present regulating mechanism in the position assumed during exhalation;

Fig. 5 is a top plan view of the present apparatus with portions cut away;

Fig. 6 is a graph illustrating the breathing resistance encountered in prior breathing devices; and

Fig. 7 is a graph similar to Fig. 6 showing the breathing resistance of the present breathing apparatus.

Referring primarily to Fig. 1 of the drawings, the breathing apparatus of the present invention is shown as indicated generally at 10. In general, the apparatus includes a regulator 11 that is attached by any suitable means to a source of breathable gas such as, for example,

a tank 12. The regulator 11 is connected, by means of a flexible non-collapsing inhalation conduit 13 and a similar exhalation conduit 14, to a suitable mouthpiece indicated generally at 15. The conduits 13 and 14 have sufiicient length so that they may extend preferably about the shoulders of the user to insure freedom of movement without undue slack that would permit their becoming fouled in objects or structures passed by the wearer.

The regulator 11 includes a unitary body portion 16 that is provided with a first chamber 17 for receiving a breathable gas and a second chamber 18 for receiving exhalation products. The chamber 17 communicates with the inhalation conduit 13 by means of a passage 19 formed laterally in one side of the body 16, the outer end of which is formed with a boss 20 to which the conduit 13 is secured by means of a clamp 21. .The chamber 18 communicates with the conduit 14 by means of a passage 22 that is formed laterally in the other side of the body 16 and terminates Within a boss 23, the conduit 14 being secured thereto by means of a clamp 24. A partition 25 is positioned in a recess 26 formed in the bottom of the chamber 18 and is secured to the body portion 16 by means of a plurality of screws 27. The partition 25 thus separates and forms adjacent sides for the

chambers

17 and 18.

The body 16 of the regulator includes a downwardly extending portion 28 (see also Fig. 2) that extends from the portion of the body forming the chamber 17. A nipple 29 is threadably disposed, as at 30, in the portion 28, and has an axial bore 31. The nipple 29 is secured to a fitting 32 of a supply tank shut-off valve 33'by means of a nut 34. A filter 35 may be positioned in the bore 31. Breathable gas from the tank 12 is conducted through the valve 33, filter 35 and bore 31 to a recess 36 in the portion 28. p i

A restricting passage 37 is formed radially outwardly from the recess 36, the outer end of this passage being provided with a conical seat 38 against which a closure member 39, of a gas reserve valve, indicated generally at 40, is adapted to rest. The closure member 39 is generally triangular in cross-section (see Fig. 2) and is slidably disposed in a laterally extending cylindrical bore 41 formed in a projection 42 from the portion 28 of the body 16.

A,fitting 43, having an internal recess 44 that is of substantially the-same diameter as the bore 41, is threadablydisposed in the outer end of the projection 42. The fitting 431s adapted to rotatably and slidably support a shaft 45, the inner end of which is, provided with aueIL- larged disc 46, there being a packing gland 47 disposed in the inner end of the bore 44 and about the shaft 45. The outer end of the fitting 4.3. h s a cam surface 48,- that is adapted to co-operate with a cam. follower 49, formed: on a lever 50, the shaft 55 extending throughthe lever and being sec red ther o. by m ans. 01.5 a nut: 5.1- The disc 46 is provided with a peripheral; grgovgfil, Fig. 3 t a ap ed eo-ene ete with a. stop. ab .53. h ext nds ewer t ies; rom he fitt 4 o a toleek the shaft in its axial position at each end of. the travel ofthe lever 5Q and provides a stop means to limit rotation f the r: Thu an f eet at ess re etir e r thev disc 46 is eliminated. y

Pa r f. eerhs ssi h a -ins 5 and re d p respectively between the enlarged; disc; 46 of. the shaft 5 en th eles tre mehs erh. and etwee a PQr ier f 'p k n lahttfl eat! he dire. 4. A eri ar ie push, re 6 e eeeeure t 9 the s er end oi h lev 5031's by e ht he 5.7 the-eens r et e ei: theses reserve valve being such that upon rotation of the lever 50 y h ard he e rh et feee 49 wi l e ete. against the cam surface 4.8 thereby to withdraw the shaft 45,, thus compressing the spring 55 and relieving the mp e v r e t' he s ing 5 h a o in or PUIP t e rei a e ere f y de c edacume- 4 to. be. received in the seat of the bore 68. the conical surface of the portion 71 co-gperating with the matching conical surface on the valve seat 69. When the valve 70 is seated, as shown in Figs. 1 and 4, the extension 72 extends into the end of the bore 68 adjacent the conical seat 69. The construction of the operating end of the al e member is such that a posi iv occlusion of the F1 passage 68 is provided. When the valve member 70 is Under normal conditions, the closure member 39 i s maintained in a closed position, with respect to the outerend of the. restricted passage 37, by action of the com-, pression spring 54. The. force of the breathable gas e h he lo re err r et r: a ides hereof h h el need he e s i h eere r r o Pr s sure acting upon. the relatively small area of the end of the portion 38 when the member is closed. The forceoi h in s e f eieht n rma t re me th for a the. see e t i en he t of e Po n. 3 U de e eihee td t e o. he. e in e e u ly iscuss d. the Pre re. f nt a s in e ee e su e member- 3 wi e 1 h s to. e t e e er en l y hea ie f ee e rt f t Por i n. er i n rmally Pre en h s to re m th er e h r n 54. causing compression thereof and opening of the closure phragm 82 is provided with upper and lower bac ingmemb r- P it e; e Q e h h he. r

e e Pe ra 1 eas hte he rmler hd r; e h r 41, as shown in Big. 2.

An angularly disposed passage 5 8 is adapted to. con; tthe h a h b e. e rerh. h irmer end'e the r 41 to the inner end of a recess 59 formed axially in the body portion 28 adjacent the chamber 17. A. reduced e er e e 60. xte ds ew wer l om he hettom of the recess 59.

A. he a em nt, 6 as l i ri et r et s. 61a th t e s de spo ed. i h eee'se nd, 6 respectively A p ir f sea in n s 6. .er 65 a e di p oscd about the portions 6 2 and 6 3: try-provide a seal be; tween the element 61 and the body portion 16 The axial length of the portion 62 is slightly shorter than the axial depth of the recess 59, so as to present an annular shoulder 66 that defines a pressure differential area that ma be aeted p n y he P ssure. f hehr athe le ga being admitted to the inner end of the recess 59'. The element 6 1 is provided with a lateral bore 67 that commhnieetee t e ne nd of he re ees. .2 and with.v an axial bore 68 through the element 61 theouter end of the bore 68 being provided with a conical valveseat 69; that is adapted to co-operate with a metering valve mem; ber 70 The valve seat 69 together with the elernent 61 t e relative to e hedy efj h ppa a us. and. may termed e me n va ve.- ett r h Purueeee description.

The metering valve member 70 has a conical tip, or operating end "portion 71 that may be made from Nylon, or the like, for example, this portion being formed with a cylindrical extension 72/ at theaperi thereof, the portion 71 and extension 72 being adapted elesed', the pre su infer ntial: rea or hic the see within the passage 53 is, acting is main ained at a constant value due to the protrusion of the extension 72 into the bore 68. It may be seen that as the valve member 70 is m d i em i sea 62, he xtension 72 m st fi s clear the outer end of the bore 68, thus presenting a large aperture for the flow of the breathable gas from the bore 68. The relatively large contact area between the portion 71 and the valve seat 69 further greatly reduces cold flowand/or we r of th material of, the p r i n 71 and su s on r. tro bler e operating i o he. unit.

e h nk o h lv mem er 70. ex n p a l through an ax a ly ispo ope in 3 i the parti i 2.5 and n th ham A p on p n 74 is disposed about the shank of the valve member 70 be; tween the partition 25 and the head portion of the. valve member, thereby to urge the valve member toward the. valve seat 69. A second compression spring 75, having a, greater force than that or the spring 74, is dosposedj between the partition 25 and a flange 76 formed on the element 61, this second compression spring acting to op- Pos he force o he b ea a a acting p n he ar 66 in a manner andfor a purpose to be hereinafter more te ly desc ibed- A. respiration pressure responsive flexible diaphragm 82' provides a movable wall forone side of the chamber 18 t s aphragm b amp d, t e e y p t o 16. and a protective cap 83 by screws 84, Fig. 5. The

diaplates

85 and 86 that are secured to each other and to the diaphragm by rivets 87, An enlarged opening- 88 is. provided through the central area of the diaphragm 82 and

backing plates

85 and 86 for reception of a bushing 89,. The bushing 89 may be of semi-flexible material such as rubber, for example, and provided with a. cylin-. drical portion 90 that is adapted to be received in the opening 88, there being an annular flange 91 extending over the backing plate 86 adjacent theperiphery of the opening 88. The bushing 89 has an enlarged annularportion 92 that is adapted to extend overthe-surface of the backing plate 85. An axially extending annular flange 93 is' formed on the periphery ofthe portion 92, this flange having outwardly projecting tabs 94. Theouter surface 95 of the bushing 89 has a conical configuration against which a normally closed disc check valve. member 96 is adapted to normally lie. The check valve member 96 is provided with a central stem 97 that has an enlargement 98. The stem 97 projects through a central opening 99 in the bushing 89, the portion 98 being received in an enlarged recess 1 00 in the inner side of the bushing 89. The bushing 89 is further provided with a plurality of axially extending fluid flow passages 101 to provide means for venting exhalation products from the chamber 18 to ambient atmosphere or the surrounding fluid medium. These exhalation products escape through the; passages 101,, past the check valve member 9.6 and ou hr e r 83.by wa of pe gs. .0. nd g through thecap 83.

It may be seen that the fla ge 93, formed in the bush; ing 89 and surrounding the flexible checlr valve member- 96, serves to prevent the possible wash or surge of the ambient fluid, medium, from unseating this valve' nember and flowing into the chamber 18. The periphery of the valve member 96'is thus protected against being lifted in a manner tending to reverse its position, orgca use malfunction thereof. a

The check valve member 96 may be made from any suitable flexible material such as rubber, for example. Upon outward movement of the diaphragm 82 away from the chamber 18, the valve member 96, together with bushing 89, is carried outwardly, the tabs 94 limiting outward movement of the bushing and diaphragm by ultimate contact with the inner surface 103 of the cap 83. It may be seen that the bushing 89, together with the flexible check valve member 96, eflfectively forms a unitary structure, the inner end portion of the stem 97 being. pulled through the bore 99 during assembly by means of an elongated portion (not shown) that is formed on the inner end of the stem 97 and subsequently removed after assembly. The bushing 89 merely snaps into place in the opening 88. In order to alleviate any possibility of the check valve member 96 adhering to the inner surface 103 of the cap 83, a plurality of radially extending ribs 104 are formed outwardly from a central boss 105 in the -cap. These ribs thus interrupt an otherwise smooth surface of the cap.

The stem portion of the metering valve member 70 is provided with an enlargement formed by a washer 106 that is retained in place on the end of the stem by a suitable snap ring 107, for example. An annular ring 108 is formed outwardly toward the chamber 18 from the partition 25 and spaced radially from the valve member 70. This annular ring is provided with peripheral notches 109 that are adapted to receive levers 110, the inner ends of which are bent as at 111. The ends of the bent portions 111 are adapted to engage a radially inwardly directed surface of the portion 108 to retain the levers in place. The levers 110 are adapted to extend from the valve member stem, beneath the washer 106 and outwardly through the notches 109 to normally engage the diaphragm plate 86 as at 112, the engagement ends of the levers 110 being suitably rounded in order to reduce friction between these levers and the plate. It may be seen that when the diaphragm 82 moves inwardly toward the chamber 18, the levers 110 will be depressed, thus rocking these levers about the ring portion 108 and lifting the valve member 70 from its normal position on the seat 69. The comparative lengths of the levers 110 between the notches 109 and the engagement point 112 with the diaphragm plate 108, and between the notches 109 and the point of contact with the washer 106, is such as to provide a large mechanical advantage for lifting the valve member 70 from the seat 69.

The mouthpiece 15 has a transverse section 114 that is provided with a passage 115 therethrough. The inhalation and exhalation conduits 13 and 14 are secured to the portion 114 by suitable clamps 116. A laterally extending portion 117 is formed outwardly from the transverse portion of the mouthpiece and has a passage 118 therethrough that communicates with the passage 115. A flexible member 119 is attached to the outer end of the portion 117, this flexible member having an elongated laterally extending flange 120 that is adapted to be inserted beneath the lips of a user, there being bit portions 121 that are inserted between the teeth of the user so as to retain this mouthpiece in place. The user of the apparatus must breathe through his mouth when utilizing the present device, the eyes and nose generally being covered by a suitable face plate or mask. In this connection it is to be understood that the device may be used with a suitable mask having an integral mouthpiece or with a mask wherein the breathable gas is delivered in such a manner as to permit breathing through either the nose or mouth.

During operation and use of the present breathing apparatus, in, for example, situations requiring submersion in a liquid, it is customary that the device be secured to the back or" the user, with the regulator 11 disposed substantially at the level of the lungs of the user. When placed in this manner, the surrounding fluid medium will exert on the diaphragm 82 and on the lungs of the user substantially the same pressure even though the user may assume various attitudes. L

The conduits 13 and 14 are adapted to extend over the shoulders of the individual and the mouthpiecelS is retained in the mouth as hereinbefore described. The breathable gas in the tank 12 may initially be compressed to a pressure of 2000 p. s. i., for example, and the breath-' previously described, the device provides a flow path or restricted passage for the breathable gas from the source to a point of use, this passage being defined by the 'bore' 31, recess 36, bores 37 and 41, passage 58, and bores 67 and 68 to the chamber 17, and from the chamber 17 by way of the passage 19 and inhalation conduit 13 to the mouthpiece 15. Assuming that the initial pressure of the gas supply is 2000 p. s. i., a pressure drop is experienced across the closure member 39 so that the gas existing at the inner end of the bore 41 will be at approximately 1700 p. s. i. The gas at this reduced pressure is transmitted through the passage 58 and into the inner end of the recess 59, thereafter to act upon the area 66 of the element 61, thereby to move the element 61 against the compression of the spring 75 to the position shown in Fig. 1. Inward movement of this element is limited by a plurality of downwardly extending fingers 126 from.

the partition 25 and spaced radially from the valve member 70, these fingers being adapted for engagement with the flange 76 on the element 61.

Upon inhalation, a reduction in the pressure existing in the conduits 13 and 14 as well as in the

chambers

17 and 18 is created, thus causing the diaphragm 82 to be moved inwardly toward the chamber 18 to depress the levers and lift the valve member 70 from the seat 69 as illustrated in Fig. 2. As inhalation is started and as the valve member 70 is lifted from the seat 69, a differential in pressure is created across the closure member 39, thereby, as hereinbefore described, causing the closure member 39 to move in a direction to compress the spring 54 and permit flow from the bore 37 through the bore 41 and into the passage 58. Opening and closing of the closure member 39 occurs therefore with each inhalation and exhalation cycle. Thereafter a metered amount of the breathable gas is admitted to the chamber 17 and con: duit 13 by way of restricted passages defined by the

bores

67 and 68. It may be seen that the diaphragm 82 is exposed on one side to the pressure in the chamber 18, this pressure being substantially the same pressure as existing in the lungs of the user, and on the other side to the pressure of the surrounding fluid medium, thereby to maintain a pressure in the lungs which substantially equals that of the surrounding fluid medium, thus preventing possible damage to the lungs from diflerential pressures that might otherwise exist. At the end of each inhalation, the diaphragm will return to a neutral position, as shown in Fig. l, to permit the valve member 70 and closure member 39 to close.

Upon exhalation, exhalation products are conducted through the passages 118 and in the mouthpiece 15, into the exhalation conduit 14 and chamber 18, whereupon a differential in pressure is created across the diaphragm 82 to cause this diaphragm to move outwardly until the tabs 94 engage the inner surface 103 of the cap 83, the diaphragm assuming the position indicated in Fig. 4. Exhalation gases will now flow through the passages 101, past the periphery of the flexible valve member 96, into the interior of the cap 83 and out through the openings 102 to ambient atmosphere or the surrounding fluid medium. It is to be noted that substantially no mixing of the breathable gas with the exhalation products is encountered, with the exception of the gas existing in the very small area of the passage 115 in the mouthpiece 15, thus reducing the amount of carbon dioxide present in the inhaled gas to an absolute minimum and alleviating the adverse physiological effects that may accompany re-breathing of exhalation products.

In prior devices designed to accomplish a purpose similar to that of the present invention, as the available pressure of the breathable gas was reduced through consumption thereof, it often became increasingly difficult for the user to breathe because of the force of gas pressure acting on the metering valve decreasing with respect to the substantially constant spring force urging the valve member toward closed position. In other devices, breathing resistance has been very high when the gas supply pressure was high and was reduced slightly as the supply pressure was reduced. Such devices are very unsatisfactory as consider-able fatigue is experienced by the user in an effort to overcome high breathing resistance. This undesirable condition is corrected in the present apparatus, the force of the decreasing pressure of the breathable gas upon the pressure differential area 66 being correspondingly reduced in opposition to the force of compression spring 75. Hence, the element 61 is permitted to float or move toward a position approximating that shown in Fig. 2, movement of the element 61 carrying the valve seat 69, in a floating manner, farther away from the partition 25, thus relaxing the spring 74 and reducing the force thereof tending to seat the valve member 70 on the valve seat 69. Movement of the element 61'is such that the force of the spring 74 is maintained slightly higher than the force exerted by the compressed breathable gas upon the extension 72 of the valve member, thus maintaining uniform breathing resistance. This substantially constant resistance to breathing is shown clearly in Fig. 7 by the curve '1'30,'the breathing resistance being maintained well below a desirable value of 2.7 inches of water maximum differential pressure, and at a substantially constant level throughout the entire pressure range of the gas contained in the tank 12 from 2000 p. s. i. to approximately 550 p. s. i., this lower pressure existing when the element 61 engages the bottom of the chamber 17. This condition is contrary to the situation existing in prior devices, wherein such low maximum breathing resistance has either not been maintained or the breathing resistance increased rapidly throughout the entire period of use of the air in the supply tank. In Fig. 6, a curve 131 represents the situation existing in prior devices.

As the'pressure of the breathable gas is reduced to 300 p. s. i., for example, and as the supply approaches exhaustion, the pressure differential across the closure member 39 is gradually reduced until this difierential is insufficient to overcome the force of the spring 54 in closing the closure member 39, whereupon the flow of breathable gas to the reces 41 will be shut off, thus providing-a warning to the user that the supply of gas is approaching exhaustion. Immediately, the lanyard 56 may be pulled to rotate the lever 50 .to the position shown in Fig. 2, thusmoving the shaft 45 outwardly by action of the cam surface 48 and cam follower 49, and relaxing the spring 54. This action reduces the force of the spring 54 and permits the closure member 39 to be unseated by the succeeding inhalation cycle. Thereafter, the closure member 39 remains open to 'enable free flow of 'gas to the passage '58. After such movement of the lever 50, and depending upon the physical condition of the user and the volume of 'the tank 12, five to-eight minutes supply of breathable gas then remains, permitting the user to surface or to seek a breathable ambient atmosphere.

It may thus be seen that the present device adequately fulfills the objects set vouthereinbefore and provides a "mechanism thatmay be used in a variety of situations eitherunder water or 'wherever unbreathable, eontaminated or poisonous atmospheres are encountered. In all'conditions of use, the device of the present invention is completely fail-safe in .that breakage or malfunction of .importantparts would notresult in danger to the user. 'For example, if either of the

springs

54 or 55 in the gas reserve valve should break, a free flow of gas would merely be delivered to the passage 58, and into the balance of the unit, some warning of the exhaustion of breathable gas thereafter being provided by increased breathing resistance near the point of gas exhaustion. If the compression spring 75 should fail, the force of the breathable gas acting upon the pressure differential area 66 would merely move the element 61 until the fingers 126 engage the flange 76, thus causing an increase in breathing resistance, this resistance still being acceptably low, as indicated by the curve 132 in Fig. 7, and breathing can be easily maintained. It the metering valve spring 74 should fail, a free flow of gas would be permitted to the chamber 17 until the pressure in the supply tank 12 dropped to a level that would be balanced by the reduced force of the broken spring 74 thus permitting the metering pin to resume its operation. In this condition. the excess gas flowing into the chamber 17 would be conducted through the inhalation conduit 13, through the passage in the mouthpiece 15 and through the exhalation conduit 14, into the chamber 18 thereafter to flow into the surrounding fluid medium through the check valve 96. If such a condition should exist, approximately 15 minutes of uninterrupted breathing would still be available.

It is to be noted that the present device may be readily and easily serviced and may be maintained in proper working order without a great knowledge of such devices. There are no critical adjustments necessary for any of the components of the device and no calibration of portions or elements thereof is required. Additionally, the simple and rugged design of the present device will insure a considerably longer service life than that provided by prior similar units, there being relatively few parts that will wear, such possible wear being virtually eliminated by the present arrangement. Various components of the device may be replaced by the average individual without the necessity for returning theunit to the manufacturer.

We claim:

1. A breathable gas regulating device comprising: first passage means for conducting a breathable gas from a source to a point of use; achamber in said device; second passage means for conducting expired gas from said point .of use to said chamber; a check valve for controlling fluid fiow from said chamber to the surrounding fluid; a movable wall forming one side of said chamber, said movable wall'being subjected on one side to the pressure in said chamber and onthe other side to the pres sure of the surrounding fluid; valve means for controlling the flow of breathable gas through said first passage means; means for biasing said valve means toward a closed position; means operably associated with said movable wall'for opening said valve means upon a reduction of the pressure in said second passage means and in said chamber thereby to permit flow of said breathable gas through said first passage means; and means operably associated with said valve means for substantially maintaining constant the force biasing said valve means toward a closed position and consequently the force required to open said valve means as the pressure of said breathable gas is reduced-through use thereof.

'2. A breathable gas regulating device comprising: first passage means for conducting a breathable gas from a source to a point of use; a chamber in said device; second passage means for conducting expired gas from said point of use to said chamber; a movable wall forming one side of said chamber, said movable wall being subjected on oneside to the pressure in said chamber and on the other side to the pressure of the surrounding fluid medium;-valve means for controlling the flow of breathable gas through said-first passage means; means for biasing said valve 'means toward-a closed position; means operably associated with said'movable wall for opening: said valve means upon a reduction of the pressure in said second passage means and in said chamber thereby to permit flow of said breathable gas through said first passage means; and means responsive to a reduction in pressure of said breathable gas from said source to maintain at substantially a constant level the force biasing said valve means toward a closed position and consequently the magnitude of said reduction in pressure in said second passage means and in said chamber necessary to move said movable wall and open said valve means.

3. A breathable gas regulating device comprising: first passage means for conducting a breathable gas from a source to a point of use; a chamber in said device; second passage means for conducting expired gas from said point of use to said chamber; a movable wall forming one side of said chamber, said movable wall being subjected on one side to the pressure in said chamber and on the other side to the pressure of the surrounding fluid medium; a check valve for controlling the flow of gas from said chamber, said check valve being carried by said movable wall; valve means for controlling the flow of breathable gas through said first passage means; means for biasing said valve means toward a closed position;

means operably associated with said movable wall for opening said valve means upon a reduction of the pressure in said second passage means and in said chamber thereby to permit flow of said breathable gas through said first passage means; and means responsive to a reduction in pressure of said breathable gas at said source to maintain at substantially a constant level the force biasing said valve means toward a closed position and consequently the magnitude of said reduction in pressure in said second passage means and in said chamber necessary to move said movable wall and open said valve means.

4. In a breathable gas regulating device: a regulator; a first chamber in said regulator for receiving a breathable gas from a source; valve means for controlling the flow of said gas into said first chamber; means resiliently urging said valve means toward a closed position; inhalation conduit means for conducting breathable gas from said first chamber to a point of use; a second chamber in said regulator; exhalation conduit means for conducting exhalation products from said point of use to said second chamber; a movable wall having one side exposed to the pressure in said second chamber, the other side of said Wall being exposed to the pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; means operably interconnecting said movable wall and said valve means, whereby, upon inhalation, a reduction in pressure is created in said exhalation conduit means and in said second chamber thereby to move said movable wall and open said valve means to permit a flow of breathable gas into said first chamber and into said inhalation conduit means and means responsive to variations in pressure of the gas at the source to vary the effective force of the valve closing means, such effective force being varied in a predetermined manner relative to the variations in the gas pressure at the source.

5. In a breathable gas regulating device: a regulator; a first chamber in said regulator for receiving a breathable gas from a source; valve means for controlling the flow of said gas into said first chamber; means resiliently urging said valve means toward a closed position; inhalation conduit means for conducting breathable gas from said first chamber to a point of use; a second chamber in said regulator; exhalation conduit means for conducting exhalation products from said point of use to said second chamber; a movable Wall having one side exposed to the pressure in said second chamber, the other side of said wall being exposed to the pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber, said check valve being carried by said movable Wall; means operably interconnecting said movable wall and said valve'mean's, whereby, upon inhalation, a reduction in pressure is created in said exhalation conduit means and in said second chamber thereby to move said movable wall and open said valve means to permit a flow of breathable gas into said first chamber and into said inhalation conduit means and means responsive to variations in pressure of the gas at the source to shift the closing point of said valve means and thus vary the effective force of said valve closing means.

6. In a breathable gas regulating device: a regulator; a

first chamber in said regulator for receiving a breathable gas from a source; valve means for controlling the flow of said gas into said first chamber; a floating valve seat associated with said valve means; inhalation conduit means for conducting breathable gas from said first chamber to a point of use; a second chamber in said regulator; exhalation conduit means for conducting exhala tion products from said point of use to said second chamber; a movable wall having one side exposed to the pressure in said second chamber, the other side of said wall being exposed to the pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; and lever means operably interconnecting said movable Wall and said valve means, whereby, upon inhalation, a reduction in pressure is created in said exhalation conduit means and in said second chamber thereby to move said movable wall inwardly toward said second chamber and open said valve means to permit a flow of breathable gas into said first chamber and into said inhalation conduit means. 7 V

7. In abreathable gas regulating device: a regulator;

a first chamber in said regulator for receiving a breatha ble gas from a source; valve means for controlling the flow of said gas into said first chamber; a movable seat associated with'said valve means, said seat being positioned in response to the pressure of said breathable gas;

inhalation conduit means for conducting breathable gas from said first chamber to a point of use; a second chamber in said regulator; exhalation conduit means for 0011- v ducting exhalation products from said point of use to said second chamber; a movable wall having one side exposed to the pressure in said second chamber, the other side of said wall being exposed to the pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; and means operably interconnecting said movable wall and said valve means, whereby, upon inhalation, a reduction in pressure is created in said exhalation conduit means and in said second chamber thereby to move said movable Wall and open said valve means to permit a flow of breathable gas into said first chamber and into said inhalation conduit means.

8. In a breathable gas regulating device: a regulator; a first chamber in said regulator for receiving a breathable gas from a source; valve means for controlling the flow of said gas into said first chamber; a movable seat associated with said valve means; spring means normally urging said seat away from said valve means; means to oppose the force of said spring means in response to the,

pressure of said breathable gas; inhalation conduit meansfor conducting breathable gas from said first chamber to a point of use; a second chamber in said regulator; exhalation conduit means for conducting exhalation products from said point of use to said second chamber; a movable wall having one side exposed to the pressure in said second chamber, the other side of said wall being exposed to the pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; and means operably interconnecting said movable wall and said valve means, whereby, upon inhalation, a reduction in pressure is created in said exhalation conduit means and in said second chamber thereby to move said movable Wall and open said valve means to permit a flow of breathable gas into said first chamber and into said inhalation conduit means.

94 A breathable gas} regulating, device: comprising; in combination: aregulator body; a first-chamber in; said." body; p as'sage means for conducting'a compressedbreathable gas from a source to said first chamber; a. valve memberinsaid passage means; --a-movable elementiassociated with said valvemember; said element having a valveseat adapted for operableassociation; with said? valve member; fi'rst' springmeans normally urging said" valve membertowardsaid valve seat; a pressure differential area formed onsaid element, saidfarea being subjeotedto the pressure of said: breathable gas fromsaid source; thereby to urgesaid elementand saidvalve seat toward saidvalve member; second spring means acting on said element in-a direction to opposethe force of said breathable-gas on said pressure differential area; an inhalation' conduitforconducting said=breathable gas from saidf-first chamber to a point'of' use; a second chamber formedin-saidbody; an-exhalationconduit for conducting exhalation, products from said point of use to said secondcham'ber; a diaphragm formingone wall of said second-chamber, said diaphragm havingone side exposed to thepressurein said second chamber and'the other side exposed to the pressure ofthe surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; and means operable by movement of said;diaphragmin response to an inhalation, produced reduction in pressure in said exhalation conduit'and in said; second chamber to liftsaid valve member-fromsaid valve seat thereby to permit a fiow ofbreathable gasintosaid'fi'rst, chamber and'into. said inhalation conduit.

10 A breathable gas regulating device comprising, in combination: a. regulator body; a first chamber in said body; a ,source of compressed; breathable gas; ,passage; means-for conductingsaid breathable gasfrom saidsource. to saidfirst' chamb'en a valve member in saidpassage means; a movable element associated, with, said. valve member, said element having a valve seat adapted for.

operable association with said valve member; ,fi'rstsp ring means normally urging said valve; member toward saidvalve seat; apressure differentialiarea formed; o n said', element, said area being subjected. to the pressureofi said breathable-gas from said source, thereby; to urge saidf element ands'aid valve seat toward said valvemember; second spring means acting on said' element; inb a, direction to oppose the force of,said breathable gas on said, pressure differential, area; an inhalation conduit for c.0n: ducting said breathable gas from said'fi'rst chamber to, a. point of use; a second chamber formed in said body, said: valve member extending into s'aidfsecondj chamber; an.

exhalation conduit for, conducting exhalation, products.

from saidpoint of use to saidsecond chamber; a di'al-yphragm forming one. wall of saidjsecondjchamber, ,said diaphragm having one side, exposed to thepressure, in said second 'chamb'erand the other side exposed'to the pressureof the surrounding fluidmedium; a check valve,

for controlling fluid flow from said'second chamber; and lever means operable by movementof said diaphragmhin; response to an inhalation produced, reduction in pressure, in said'exhalation conduit and in said ;second chamber. to lift-said; valve member from said'valve seat, thereby to permita flow ofbreathable gas into said first chamber and into said; inhalation conduit.

11; A breathable gasregulating device comprising, i11

combination: aregulator body; a firstehamberuin; said;

body; a source of, compressed breathable, gas; .passage means for conductingsaid breathable gasfrom said'source to ,said' first chamber; a vvalve member in said passage means; a movable element associatedwitli said VBIVBJIIGIII: ber, said element havingavalveseat adaptedforoperable, association with jsaid1valve member; first spring-means normally urging said valve member toward said yalveseatg, a pressure differential area.formed'onsaidelernent, said, area beingsubjected to the pressure of said breathablergas fromsaid'source, thereby to urge said=element andgsaid; valve seat toward said valve member; second'spring means acting on said"element in a direction to oppose theforce of saidjbreathable gas on said. pressure differential area,

aniinhalationconduirfor conducting said breathable gas fronrsaid-fi'rst chamber to a point of1use; a second chambet formed'in' said body, said valve member extending into-saidsecondcharnber; an exhalation conduit for conductingexhaiation products from said .point of use to said, second chamber; a diaphragm forming one wallof said second chamber, said' diaphragm having one side exposed to the pressure in saidsecond chamber and, the other. side exposedito the pressure ofthe surrounding fiuid'medium; a check valve for controlling fluidfiow from saidsecondj chamber, said check valve being carried by saiddiaphrag m; and lever. means operable by, movement of'said' diaphragm in response to an inhalationproduced reduc:

to said'first chamber; a valve; member, in said passage,

means; amovable}element associatedwith said valve member, saidfelernent having a valve seat adapted, for operable association with said valve member; first spring means.- normally urging. said, valve member toward said valve, se'atganressurc, differential areat ormed on saidzelement, said'area being subjected to..the.p ress.ur.e,olisaid breathable: gasfromsaid source, thereby-to urge said ,elementand said; valve seattoward said valvemember; secondspringmeans, actingon -.saidl element, in; a ,direction to oppose the .force.

of said breathable gas on said pressure differential arezu,

an. inhalation, conduit for; conducting said breathable. gas fromsaid first chamber. toapoint of vuse; a second champ ber, formed in saidbody, said valve member extending .intov said, second chambergan exhalation conduit for, conduct:- ingpxhalation productsfromsaid point of. usetosaidsec:- ond.chamb er; a diaphragmtorming one. wall; ofsaid ondLcharnber, saidldiaphragm having one side exposedto, thepressureinsaid-second chamber and the other side exposedto the pressureof the surroundinglfluid medium; a, check valve, for controlling fluid flow fromsaid second, chamber; lever'meansi operable byrmovement of said die-- phragmiinresponse, to an inhalation prcduced;reduction. in pressure,insaidexhalation conduit andin said'second chamber to lift saidvalvemember from said valveseat, thereby to permita flowofubrcathable gas into said first. chamber. and into said inhalation conduit; and means positionedzbetween said valve. member and said source of breathable gas, to interrupt the flow of'said gas when thegasnpressureof said source is reducedto a predetermined level;

13. A breathable,gasregulating device comprising, in combination; a; regulator body; a first chamber, in said body; a source, of compressed, breathable gas; passage means for conductingsaid breathable gas frornsaid source to said first chamber; a valve member in said passage means; a. movable, element' associated, withsaid valve member, said elementhaving; a. valveseat adapted for operableassociation ,withsaid valve member; ,first spring, meansnormally urging said valve, member, toward gsaid. valve seat; .a pressure, differential areaformed onsaid element, .said .area being subjected tothe pressure, of said: breathable; gas from said ysource, thereby to urge said ,element and-said valve-seattowardtsaid valve member; second spring;means acting onsaid element in a directiomtm oppose the force of, said, breathable ,gas on said pressure, differential. area; an inhalation conduit forconductingz saidv breathablehgas from saidlfirst. chamber to a pointyof use; a;,second chamber, formed in-said body,v saidrvalye; member extending into'saidsecondchamber; .an exhala:-- tion ,conduitfor conduetingexhalation. roductsfrom said point of use to said second chamber; a diaphragm forming one wall of said second chamber, said diaphragm having one side exposed to the pressure in said second chamber and the other side exposed to he pressure of the surrounding fluid medium; a check valve for controlling fluid flow from said second chamber; and lever means operable by movement of said diaphragm in response to an inhalation produced reduction in pressure in said exhalation conduit and in said second chamber to lift said valve member from said valve seat thereby to permit a flow of breathable gas into said first chamber and into said inhalation conduit; means positioned between said valve member and said source of breathable gas to interrupt the flow of said gas when the gas pressure of said source is reduced toa predetermined level; and manually operable means to override said interrupting means.

14. A breathable gas regulating device comprising, in combination: a unitary regulator body; a source of compressed breathable gas; a breathable gas receiving chamber formed in said body; a flow restricting passage intermediate said source of breathable gas and said chamber; an inhalation conduit for conducting said breathable gas from said receiving chamber to a point of use such as the respiration system of an individual; a valve member positioned in said breathable gas receiving chamber and adapted normally to occlude one end of said passage; a movable element associated with said valve member, said element having a valve seat adapted for operable association with said valve member; first spring means normally urging said valve member toward said valve seat; a pressure diflerential area formed on said element, said area being subjected to the pressure of said breathable gas from said source, thereby to urge said element and said valve seat toward said valve member; second spring means acting on said element in a direction to oppose the force of said breathable gas on said pressure difierential area; an exhalation products receiving chamber formed in said valve body adjacent said breathable gas receiving chamber; a partition separating said chambers, said valve member extending from said breathable gas receiving chamber through said partition and having a portion disposed in said exhalation products receiving chamber; an

' exhalation conduit extending between said point of use to said exhalation products receiving chamber; a flexible diaphragm forming one wall of said exhalation products chamber, said diaphragm having one side exposed to the fiuid pressure within said exhalation products receiving chamber and the other side exposed to the pressure of the surrounding fluid medium; a bushing positioned in substantially the central area of said diaphragm; fluid flow passages formed in said bushing, thereby to provide communication between said exhalation products chamher and an ambient medium; a flexible disc check valve associated with and adapted normally to occlude said passages in said bushing, thereby permitting fluid flow only outwardly from said exhalation products chamber; an annular ring extending from said partition intermediate said chamber, said ring being spaced radially from said valve member; an enlarged head on said valve member; a plurality of levers extending over said annular ring and beneath said enlarged head, said levers being adapted to engage and be depressed by said diaphragm upon movement thereof inwardly toward said exhalation products chamber, said inward movement of said diaphragm being caused by an inhalation produced reduction in pressure in said exhalation conduit and in said exhalation products chamber, thereby to lift said valve member from said seat to permit the flow of breathable gas from said source to said breathable gas receiving chamber and through said inhalation conduit to said point of use; a

an inhalation conduit for conducting said breathable gas from said receiving chamber to a point of use such as the respiration system of an individual; a valve member positioned in said breathable gas receiving chamber and adapted normally to occlude one end of said passage; a movable element associated with said valve member, said elementhaving a valve seat adapted for operable associ ation with said valve member; first spring means normally urging said valve member toward said valve seat; a pressure differential area formed on said element, said area being subjected to the pressure of said breathable gas from said source, thereby to urge said element and said valve seat toward said valve member; means to limit movement of said element due to the force of said breathable gas; second spring means acting on said element in a direction to oppose the force of said breathable gas on said pressure differential area; an exhalation products receiving chamberformed in said valve body adjacent said breathable gas receiving chamber; a partition separating said chambers, said valve member extending from,

said breathable gas receiving chamber through said partition and having a portion disposed in said exhalation products receiving chamber; an exhalation conduit extending between said point of use to said exhalation products receiving chamber; a flexible diaphragm forming one wall of said exhalation products chamber, said diaphragm having one side exposed to the fluid pressure within said exhalation products chamber and the other side exposed tothe pressure of the surrounding atmost phere; a bushing positioned in substantially the central area of said diaphragm; fluid flow passages formed in said bushing, thereby to provide communication between said exhalation products chamber and ambientatmosphere; a flexible disc; check valve associated with and adapted normally to occlude said passages in said bushing, thereby permitting fluid flow only outwardly from said exhalation products chamber; an annular flange surrounding the periphery of said flexible check valve to prevent inadvertent lifting of said flexible check valve from said fluid flow passages by surging of ambient atmosphere; an annular ring extending from said partition intermediate said chambers; said ring being spaced radially from said valve member; an enlarged head on said valve member; a plurality of levers extending over said annular ring and beneath said enlarged head, said lever being adapted to engage and be depressed by said diaphragm upon movement thereof inwardly toward said exhalation products chamber, said inward movement of said diaphragm being caused by an inhalation produced reduction in pressure in said exhalation conduit and in said exhalation products chamber,v thereby to lift said valve member from said seat to permit the flow of breathable gas from said source to said breathable gas receiving chamber and through said inhalation'conduit to said point of use; a spring loaded closure member positioned in said restricted passage between said source of breathable gas and said valve member, said closure member being adapted to be opened by an inhalation created pressure differential thereacr'oss, said closure member being adapted to shut off the flow of breathable gas from said source when the pressure of said breathable gas from said source is reduced to a predetermined level; and means to manually reduce the spring force acting to maintain said closure member in its shut off position.

16. A breathable gas regulating device comprising, in combination: a unitary regulator body; a source of corn- 15 Pres edhr athable g ssa breath ble gastreceiv ng 1 11 er. tormed in said. body; a w r stri t ngrass ge intermediate said source of breathable, gas. and said Chamber; n i h la i n. d tfe conduct ng. aid bre th b a from sai r cei ingv chambe t a po nt f. seuch. as-

th resp i n sy t m of. ndividual; v lve. member Pos tione in. aidj receiving h mbe and; ada ted, noral to o clu n en of. aid, p ss ge; a movable. leent associa e w t said. valv mem er. n sl dably spos d n aid reg l tor. o. y, sa d ele n i g a valve seat adapted for operable association with said valve member; firs pring means normal y urging, said. v l e member toward said. valve. sea anressu e ifferentiial rea. fo m d on said lement, sai ar a b i g ubi eted o he pr s ure ofhrea hahle ga f om.s.aid sour.e there y rge. ai l ment..anc1; aid;val. e se t. to ar d alv memb r; means. carried y ai e elnenttor lim ting movement. he of. du to. a d. pressure ofqsaidj breatha le gas; n ta ing me ns cting o aidl la ment in a direction to oppose, the force of said breathable ga n id P s re. dilfteren ial r an. xhalat ontprqdv e ei g h mb r. f rmed in ai val b'ody cilia: c nt said reatha gas r eiving cham er; par i on. separating. sa d h.amh .rs,.. id lv m mb r. extending from said brea hable ga -r ce g. chamber thlr ghl a exha lapartition and having a portiondijsposedinsai P ducts receivi g, c a ber; an xh la ion. condui ex ndi g. b w en. ai p in of e o-sa djexha l t o products receiving. chamber; a flexible diaphragm forming one wall of said, exhalation products chamber, said diaphragm having one side exposed to the fluidpressure. within said exhalation products. chamber and the other side exposed to the pressure of the surrounding fluid medium; a bushing positioned in substantially the central area of said diaphragm; fluid fl'ow passages formed in said bushing thereby to provide communication between said exhalation products chamber and the surrounding fluid medium; a flexible disc checkvalve, associated with and adapted normally to occlude. said passages in said"bushin-g, thereby permitting fluidflow only outwardly from said exhalation products chamher; an; annular flange surrounding the periphery ofjsaid flexible check valve to prevent inadvertent lifting ofsaid flexible, check valve from said fluid flow passages, by surging of said fluid medium; an annular ring extending from said partition intermediate said chambers, said ring being spaced radially from said valve; an enlarged" head on said valve member; a plurality of levers extending over said annular ring and beneath said enlargedhead, said lever being adapted to engage and be depressed by said diaphragm upon movement thereof inwardly toward saidexhalation products chamber, said inward movement of said; diaphragm being caused by an inhalation produced reduction in pressure in said" exhalation conduit andin said exhalation products cham- 1 ber, thereby to lift said valve member from said seat to. permit the flow of breathable gas from said source to said breathable gas receiving chamber and through said" inhalation conduit to said point ofv use; a spring loaded" closure member positioned in said restricted passage be tween said source of'breathablje gas and said valve member, said closure member being adapted to be opened'by an inhalation created pressure ditferential thereacross, said closure member being adapted to shut off the flow of breathable gas from said" source when the source. pressure of said breathable, gas is reduced to a predetermined level; and means to manually reduce. the spring force acting to maintain said closure member in its shut off positron.

17. A breathable gas regulating device comprising; first passage means for conducting a breathable gas from a source to a point of use; a chamber in said device; second passage means for conducting expired'gas from said point of use to saidchamber; a movable wall forming one side of said" chamber, said movable wall being subjected on one side to. the pressure in said chamber and on the other side to the pressure of the surrounding fluid. medium; valve means for controllingthe. flow of breathable gas through said first passage means;means operablyassociated with said movable wall for opening said valve meansupon a reductionv of the. pressure in. said second passage means and in said chamber thereby to permit, flew of said breathable gas through said first passage means; and gas reserve valve means positioned, upstream from said, valve means for interrupting the flow of said breathable, gas when the source pressure thereof i'sreduced to a predetermined level.,

18: A breathable, gas regulating device comprising; a. source of breathable gas; a first passage for conducting breathable gas from said source to a point.offuse;.an

whereby to open said, valve upon an inhalation produced reduction in pressure, on said other side of said dia.-- phragm; and gas reserve valve means disposed in said, first'passage. to limitfl'ow of said breathable gas to said. firstpassage when a predetermined low pressure limit of' gas from said, source is reached.

'19; A breathable gas regulator comprising; a body formed for connection with. a source ofcompressed gas and? with conduitsleading to and from a point of'use; a diaphragm: secured to saidbody for movement in response to, pressure differences on opposite sides thereof, 'said' diaphragm having a firstv side exposed to ambient fluid and a second side exposed to the pressure at the point ofv use offthe'gas; valve means in said regulator for controlling-the'flow of gas from said source into said regulator; lever means transmitting motion from said diaphragm to a portion of said valve means, movement of said diaphragm-in'response to pressure reductions on saidsecond side serving-to move said valve means in an opening direction; signal means in said body operative when the gas in saidsource approaches depletion to resist move:- ment of a portion of said valve means in anopeningdirection; and manually operable means insaid body' for" diaphragm; saiddiaphragm being exposed on one side to thepressure of the; surrounding fluid medium; the other side-of saiddiaphragm being exposed to-. pressure of thegas delivered tothepoint of use; an exhalation valve having a discharge opening to-said' fluid medium; secondpassage means extending from-said point of use-to said exhalationvalve; means operatively connecting said dia phragm: and said inlet valve to open the latterupon an inhalationtproduced reductionin pressure -upon said other sideof said diaphragmgas reserve valve meansdisposed in said first passage; means resiliently urging said reserve valve' meanstoward a closedi positionto resist'the flow of breathable gas through saidfirst passage; and selectively operated means for rendering said urging means inoperative and relieving such resistance to breathable gas flow.

2'1; A breathable gas regulating device comprising; a-

source of breathablegas; means forming a first passage for conducting breathable gas from saidsource to a point' ofuse; means forminga floating valveseat in said'passage, forming means, said valve seat having a. bore constir tuting part ofsaid' fi'rst passage; an inlet valve in said first passage, said inlet valve having an extension of predetermined cross-sectional area and length to enter and close the bore in said floating valve seat prior to engagement of the valve With said seat; means resiliently urging said inlet valve toward a closed position; a respiration responsive diaphragm, said diaphragm being exposed on a first side to the pressure of the surrounding fluid medium and on the second side to the pressure of the gas at the point of use; an exhalation valve having a discharge opening to said surrounding fluid medium; second passage means leading from said point of use to said exhalation valve; means operatively connecting said diaphragm and said inlet valve to open the latter upon an inhalation produced reduction in pressure upon said second side of said diaphragm; and means for applying breathable gas from said source to said floating valve seat forming means 5 variations in gas source pressure.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,269,904 Erickson Jan. 13, 1942 2,552,595 Seeler May 15, 1951 2,695,609 Nourse Nov. 30, 1954 FOREIGN PATENTS 503,950 Belgium Oct. 10, 1952 663,202 Great Britain Dec. 19, 1951