US1935655A - Apparatus for supplying respirable atmosphere under abnormal respiratory conditions - Google Patents

Description

W 1933- c. B. MOMSEN ET AL APPARATUS FOR SUPPLYING RESPIRABLE ATMOSPHERE I UNDER ABNORMAL RESPIRATORY CONDITIONS Filed July 17; 1929 3 Sheets-Sheet 1 Nov. 21, 1933. c. B. MOMSEN ET AL APPARATUS FOR SUPPLYING RESPIRA BLE ATMOSPHERE UNDER ABNORMAL RESPIRATORY CONDITIONS Filed July 17, 1929 INVENTOR. CHARLES B. IVOMSEN 3 Sheets-Sheet 2 CLARENCE L. T/BBALS FRANK M HOBSON A A TORNEY.

Nov. 21, 1933.

c. B. MOMSEN ET AL 1,935,655 APPARATUS FOR SUPPLYING RESPIRABLE ATMOSPHERE UNDER ABNORMAL RESPIRATORY CONDITIONS Filed July 1'7, 1929 3 Sheets-Sheet 5 INVENTOR.

CHARLES B. MOMSEN CLARENCE L. T/BBALS BY FRANK M. HOSSON Patented Nov. 21, 1933 UNITED STATES APPARATUS FOR SUPPLYING RESPIRABLE ATMOSPHERE UNDER ABNORMAL RE- SPIRATORY CONDITIONS Charles B. Momsen, St. Paul, Minn Clarence L. Tibbals,'Fort Wayne, Ind., and Frank M. Hobson, Birmingham, Ala.

Application July 17, 1929, Serial No. 379,018, and in Great Britain November 9, 1928 24 Claims. (01. 128-191) (Granted under the act of March 3, 1883, as

- amended April 30, 1928; 370 0. G. 757) Our invention resides in the method of supplying respirable atmosphere under abnormal respiratory conditions thereby enabling persons to emerge and safely ascend from submerged vessels or to carry out operations at great depth, or under other abnormal respiratory conditions without danger of resulting disability.

Our invention also resides in the apparatus whereby we have been able to practice the said method of supplying respirable atmosphere under abnormal respiratory conditions.

Before specifically stating the objects of our invention, the conditions attendant upon operations at great depth and the physiological effects of high pressures and vitiated air will be briefly stated in terms of an escape from a sunken submarine. The present types of apparatus will then be discussed and attention called to the disadvantages of each in order that the objects and advantages of .our invention may be apparent.

Submarines are provided with torpedo tubes, .conning towers or escapelocks within which it is possible, by means of partial flooding or charging with air, to create an air pressure equal to that exerted by the outside surrounding water, to permit the outside hatches of such compartments to be opened to the sea by the persons within.

Apparatus heretofore invented for escape purposes have not proved satisfactory for the following reasons: I

Their weight and bulk have been such as to preclude their stowage in the limited spaces available for this purpose on submarines. Their complicated parts and principle of operation have been such as to require extensive training in their use. Those of the helmet type have their depth limitations by virtue of the fact that the height of the compressed air bubble created in the upper portionof the helmet by the entrance of the surrounding water through the base of the helmet is dependent upon the pressure of the surrounding water. The operator is supposed to breathe within the bubble, the height of which decreases with any increase in the outside water pressure.

At deep depths this decrease issuch as to permit the water level within the helmet to rise above the operators mouth and nose. Also, operators of this type of apparatus must remain upright in the water as otherwise the tilting of the helmetwill result in the air bubble escaping through the bottom of the helmet with the result that the op erator will probably drown.

In some types of artificial breathing devices for under-water work, the source of respirable atmosphere is usually either an inflatable or rigid reservoir which is fed by means of high pressure oxygen flasks and, or, compressed air cylinders connected by high pressure oxygen or air piping to the reservoir. Usually the oxygen flasks are fitted with reducing or injector valves which are supposed to deliver a constant volume of oxygen per unit of time.

The valves of the compressed air tanks are supposed to be manipulated by .hand to dilute the oxygen within the reservoir as considered necessary by the operator. The operator exhales into and inhales from the reservoir by means of a mouthpiece and tubes leading therefrom, the exhaled air passing through a chemical container for absorbing the carbon dioxide generated by the operator. In using the apparatus the operator usually charges the reservoir to approximately its maximum capacity from the oxygen flask attached thereto. Therefore the initial pressure of air within the reservoir is usually in excess of the pressure of the surrounding water in which the operator is working. This reservoir being buoyant forces the operator to ascend through the water unless sufficient weights are attached to him to overcome the posi tive buoyancy of the apparatus. On his ascent through the water the surrounding pressure decreases, and the pressure within the reservoir andthe operators body becomes greater than the external pressure. If the reservoir is of the inflatable type this results in an increase in the size of the reservoir thereby constantly increasing its buoyancy and accelerating the ascent. Under these conditions the inability of the operator to expel the excess air pressure within his body has a deleterious physiological efiect which may prove fatal on attempts to ascend from great depths. Also, during ascent the only outlet for the excess air pressure within the reservoir and the operators body is through the mouthpiece. In deep depths the combined efforts of the excess pressure to escape from the reservoir and the body through the one common point, the mouth, is such as to blow the mouthpiece from the operators mouth, causing serious results.

In addition to these disadvantages, such apparatus, when used in deep water operations generates an excess resistance to breathing, as will be more fully described hereafter, due principally to the conditions above mentioned and the fact that exhalations are made through a container charged with a carbon dioxide absorbent, which being in the air reservoir is always about one foot deeper in the water than the operators mouth when the operator stands in an upright position. This difference of one foot in depth results in the outlet end of the container being subject to a pressure of about one-half pound per square inch greater than at the operators mouth or inlet end of the container and also results in excess resistance to exhalations and retards continuous circulation of air from the operator's lungs to the breathing bag and vice versa; thereby increasing the carbon dioxide content of the operators alveolar air, creating the necessity for more rapid breathing with a consequent increased rate of oxygen absorption by the body. Therefore, in apparatus of this type the danger of building up an excess of carbon dioxide not only has to be guarded against, but the possibility of the oxygen consumption being greater than the quantity delivered by the automatic and injector type valves constitutes a potential hazard.

Having described the dangers and disadvantages of the various types of apparatus used heretofore, we will now recite specifically the more important objects of our invention.

One object of our invention is to provide a method of supplying respirable atmosphere whereby the lungs, bronchial tracts, etc. of the human body may be utilized as a reservoir for air compressed therein while the operator is in a submarine compartment and using this air in conjunction with an extraneous reserve of respirable air in the apparatus during ascent and decompression, thereby reducing the size and weight of the latter to that which can be conveniently carried on board submarines.

Another object of our invention is to provide a method of supplying respirable atmosphere in such a manner that normal respiration is safely maintained regardless of the abnormal varying conditions of the external and internal pressures and in which the time the apparatus will support respiration increases directly with the depth from which the apparatus is used.

Another object of our invention is to provide a method of supplying respirable atmosphere whereby said respirable atmosphere is maintained constantly in equilibrium with the air within the lungs and body regardless of the pressure exerted by the surrounding medium, thereby permitting a normal respiration without undue pressure resistance and thereby eliminating excess strains on the jaw and throat muscles to which the operator would be otherwise subjected.

Another object of our invention is to provide an improved apparatus which will satisfactorily function without such adjuncts as integrally attached oxygen flasks or compressed air flasks and holding-down weights for the apparatus.

Another object is to provide an improved apparatus whereby the air reservoir may be inflated with a respirable atmosphere, such as oxygen, from the supply carried aboard submarines, or from a small detachable flask carried on the apparatus, or by the compressed air usually available in the compartments, escape locks, conning towers-and torpedo tubes of submarines, or from the lungs of the operator himself.

A further object is to provide an improved apparatus whereby, with a specially designed mouthpiece, no discomfort or difliculty will be experienced by the. operator in maintaining a suitable and proper conduit between his lungs and the apparatus.

To those skilled in the art to which our invention relates, many changes in construction .and applications of the invention will suggest themselves without departing from the spirit and scope thereof.

Details of the invention will hereinafter be described and claimed, and modifications thereof will be apparent to those skilled in the art to which our invention relates, and within the scope of the appended claims, from the following description, taken in connection with the accompanying drawings, wherein:-

Figure 1 is a general view of the manner or escape from one type of submarine,

Figure 2 is a vertical elevation of the breathing apparatus with parts broken away to show the absorbent container,

Figure 3 is a side view,

Figure 4 is a vertical longitudinal section on an enlarged scale of the absorbent container,

Figure 5 is a section on the line 5-5 of Figure 6,

Figure 6 is a plan of Figure 5,

Figure 7 is an end view of Figure 6,

Figure 8 is a section on the line 88 of Figure 5,

Figure 9 is a side elevation of the mouthpiece, and

Figure 10 is a vertical longitudinal section thereof,

Figure 11 is a side view of the vent valve. I

We prefer to illustrate our invention as it is applied to emergence and ascent to the surface from a sunken submarine, but it will be understood that the invention is applicable for use in other kinds of operations where normal atmospheric conditions do not exist; such as for example as emerging from a disabled sunken submarine and entering another submarine or a diving bell that may be placed alongside, or in entering flooded spaces requiring submergence for considerable periods, or in entering spaces containing toxic or vitiated atmosphere.

It will also be understood that while our invention is shown in the form of attachable apparatus, the principles embodied therein are equally applicable to inflated garments or suits.

Referring more particularly to Figures 2 and 3, the breathing apparatus comprises an inflatable bag 15, preferably of rubber, the sides and 125 bottom of which are constituted of and connected by a folded piece of rubber as is customary with some makes of breathing bags. Within the bag is a receptacle 16 for containing a chemical suitable for absorbing carbon dioxide 130 from the exhaled breath, or for absorbing other noxious gases as well as carbon-dioxide.

This container comprises (Fig. 4) a main supporting plate 17 soldered or otherwise connected to the top of the container 16 there being an 135 outlet nipple 18 inserted through the plate 17, and the bag is held in place by nuts 19 and 20. The nipple 18 carries a fine wire screen 21 which is spaced above an upper wire screen 22 in the container. This space is sufliciently large to pre- 14G vent saliva from closing subsequent screen meshes, and provides an initial volume of respirable atmosphere to satisfy the first muscular efforts of the lungs.

Resting on wire screen 21 and working with 14: a sliding fit in nipple 18 is a fine wire cone screen 210. The purpose of thisscreen is to prevent drops of water or saliva (should they get into nozzle 18) blocking the air passage through screen 21. For example if drops of water through 15 condensation or otherwise collect on cone screen 21a they trickle to the base of the cone, leaving a clear air passage near the top.

Between the upper wire screen 22 and a wire screen 23 extending across the open bottom of the container is held the absorbent, which is placed therebetween through a filling opening 24 closed by a screw cap 25.

The plate 17 is also provided with an inlet nipple 26 screwed or otherwise secured to the plate, which extends beyond the side of the container. The nipple passes through the material of the bag and has a clamping nut 27.

Bag 15, Fig. 2 is also provided with a nonreturn inflating valve 28, preferably placed so that the inner end will be opposite the container but not attached thereto, so that the container will form a rigid support against which the inner end of the valve may rest when connecting a source of inflating gas thereto.

The upper end of the bag is provided with tabs 29 in which are metal loops 30 between which a shoulder strap 31 is connected. Similar tabs 32 are at the sides of the bag, also provided with metal loops to one of which is attached a belt strap 33.

To the other side tab is connected a loop or pocket 34, preferably of fabric, in which is frictionally retained a bottle 35 for respirable fiuid, preferably compressed oxygen, and provided with a valve 36 to which is connected a short hose 37 having a fitting 38 for connecting it to the inflating valve 28. The supply in the bottle is intended to be small, and after its use the bottle and its hose may be thrown away.

Connected to the fabric pocket 34 is a metal loop 39 to which is attached a short chain 44a carrying a clamp 41 for clamping the belt thereto. Clamps have been found quicker and easier to manipulate than buckles, where a delay of a few seconds may mean life or death.

At the bottom of the bag are tabs 42, loops 43, short chains 44 and clamps 45 similar to those above described, to be clamped to the operators trousers, and constitute holding down straps to prevent the bag from floating up over the operators face when in the water.

The nipples 18 and 26 are respectively connected to readily flexible corrugated breathing tubes 46 and 47. These tubes differ from the customary breathing tubes in that they are moulded together at 48 between their ends. The upper ends of these tubes are connected to the breathing valve casing 49 provided with a cut-off valve 50 and a mouthpiece 51. Tied to the valve casing 49 by lanyard 52 is a well known form of nosepiece 53.

Secured to one side of the bag near the bottom is a tubular fitting 54 to which is attached a fiexible tube 55 having at its end an automatic vent valve 56 that dangles below the bag 15 and is adjustable as to distance below the bag, here shown by tying the tube 55 intermediate its length by a cord to the fitting 54. Any other means for lengthening and shortening the tube 55 to control the relative internal pressure may be used.

The valve that has been used, Figures 2 and 11, primarily consists of two sheets of rubber 58 and 59 vulcanized together at the edges and slitted at the sides. This is conveniently done by leaving the joint open at the sides, as at 60, Figure 11. This valve automatically opens when the internal pressure in the bag exceeds the external water pressure on the valve. The pressure in the bag and in the body of the operator is in excess of the water pressure at the mouth of the operator when upright by about one-half pound for every foot the valve is below such point, so that by varying the distance from mouthpiece to valve the pressure in the bag in excess of the external pressure is regulated.

The breathing valve casing 49 is cylindrical, Figures 5 and 8, and has in it two walls 61 and 62 inclined to one another so as to be wider apart toward the cut-off valve 50 and mouth-piece 51, and are connected by a portion 63 so as to form a. chamber 64 between them.

The seats 65 are tapered and the valves 66 and 67 are limited in their movements by guards 68. These valves are of mica or other suitable light material, and are of the usual flutter valve type. By inclining the walls 61 and- 62 and the seats that carry these valves they offer much less resistance to breathing than when otherwise arranged, which is a distinct advantage.

The valve casing has two nipples 69 and 70, the one 69 connected to the inlet tube 46 directly connected to the container 16 that delivers respirable fluid through the inlet valve 66 into chamber 64 and the mouthpiece, while the other valve 67 controls the discharge of expired atmosphere from the mouthpiece 51 to chamber 64 and a chamber 71 and nipple to the tube 47 leading to the bag 15.

The mouthpiece is of rubber and fits over an extension 72 of the cut-off valve 50, and is made to so fit the mouth that the blowing out of the mouthpiece is effectively avoided without I any head straps to hold it in place. This is a decided advantage to the wearer and saves much time in fastening the apparatus to-the operator.

The mouthpiece shown in Figures 6 to 10 comprises a portion '73 to fitover the nipple 72. It is provided with a rubber plate 74 curved to cover the mouth and so shaped as to exert pressure on the upper lip under the nose, to prevent the desire to sneeze, which desire is common to all divers and sub-aqueous workers. The sides extend far enough to the side of the face to cover the corners of the mouth and support the cheeks against distension. Another plate 75 is spaced therefrom and lies against most of the teeth between them and the lips, forming with the plate '74 a groove 76 in which the lips lie. There is a dome 77 fitting the roof of the mouth and just back of the front teeth which forms with the plate 75 a groove 78 in which the teeth lie.- This dome 77 merges into vertically shorter portions 7711 that fit against the lingual surfaces of all of the teeth and are provided with lateral flanges 78a for insertion between the upper and lower sets of teeth, and to this end is narrowed or tapered toward the rear of the mouth, as shown, so as to maintain the breathing passage '79 always open. In this manner all the teeth cooperate to hold the mouthpiece in place, and can be used by an operator having one or more teeth missing, which cannot be done with apparatus now in use, where resort has to be made to the tightly strapped head straps to hold the mouthpiece in place.

In describing the method and use and principle of operation of the apparatus, its application to escape and ascent from submerged submarines under one of the conditions usually attendant on submarine disasters will be cited.

For this purpose it will be assumed that in disabled sunken subm'arines, the living personnel will be gathered in unfiooded or partially flooded compartments which are fitted with either a conning tower or an escape lock or torpedo tubes.

In unflooded compartments the occupants would enter the conning tower or escape lock 80, Fig. 1, and after closing the intervening door 81, flood the tower or lock by operating valves 82, installed for this purpose. As the water rises it compresses the air within these spaces, forming at the top an air bubble, the pressure of which becomes equal to the external pressure of the outside sea water. During the building up of this pressure, the occupants don the apparatus by slipping the straps 31 over the head; clamping the belt 33 and the holding down straps or chains 44 around the waist and to the trouser legs, respectively, by means of the clamps 45. The loose end of the supply hose 87 leading from the oxygen or compressed air tanks, 88 within the conning tower or escape locks being equipped with a special spring type air valve to fit by normal hand pressure over the spring return plunger valve type inlet valve 28 on the inflatable bag 15, this connection is quickly and momentarily made, thus inflating the bag and displacing any vitiated air with a respirable atmosphere. The operator exhales and then the mouth piece 51 is adjusted over the lips and between the teeth of the operator, after which he inhales from the bag. Then the bag, is if necessary, again inflated by momentarily holding the oxygen or compressed air hose to connection 28. The nostrils are then sealed by the clip 53.

The operator is then ready to emerge from the conning tower or escape lock when the air pressure, which has been building up within, equals the external pressure of the surrounding water.

When this pressure is attained the side door of the escape lock, or overhead hatch of the conning tower is readily opened to the sea. The men emerge one by one, the first man releasing a line 84 to one end of which is attached a small buoy 85 preferably made of water-proofed balsa wood, which upon release floats to the surface, pulling the line after it. The line is provided with well defined stops 86 throughout its length and at proper distance apart for determining points of necessary stoppage of the operator for proper decompression during his ascent. The other end of the line is made fast to the submarine.-

It is a well known fact that men submerged in water under high pressures-can rapidly float upward certain distances without physical detriment, consequently the first man emerging from the submarine rapidly ascends the buoy line to within a certain distance from the surface, easily predetermined and gauged by him by the abovementioned stops on the cable. At this point he halts his ascent for the required interval of time to obtain proper decompression at this depth. When he is ready to continue his ascent he signals his intent, by a pull on the line, to the next man who is standing by the conning tower or escape lock hatch ready to ascend. process is thus continued until all of the occupants of the submarine have ascended. After leaving the first stop on the buoy line, additional stops at successive stages and-for required periods are made, until the men finally successively reach the surface.

As the apparatus has a small positive bouyancy there is no downward pull exerted by the men on the buoy line. Consequently any number of men may simultaneously ascend the line without fear of sinking the buoy. As many as four men can stop simultaneously for decompression at any successive stops. This and the fact that the time for proper decompression at the initial stop is always of short duration enables the rapid departure of the men from the submarine. For example it would be possible for men to emerge from sunken submarines individually or in groups of four at about two minute intervals.

To accomplish this proceedure it is necessary that a respirable atmosphere in suflicient quantity to last the operator until he reaches the surface be readily available during his ascent; that the means of supplying this atmosphere be such that it can be utilized by the normal respiratory functions of the body, and that the principle of supplying his respiratory needs be such that there is no disturbance of a predetermined proper buoyancy.

This is accomplished with this apparatus by the normal inhalations and exhalations of the operator and the. proper arrangement of valves controlling the directional flow of inspired and expired atmosphere; by the necessary equilibrium in pressure between the air within the body and the inflatable bag and the varying pressure of the surrounding water, and by the constant displacement of the inflatable bag regardless of the changing external pressure conditions.

In this apparatus, as stated in the foregoing, the capacity, of the bag 15 when once normally inflated is such that the reserve ,of respirable atmosphere contained therein plus the high pressure atmospherewith which the operators body is initially charged is sufficient to adequately meet his respiratory requirements for proper periods of decompression during his ascent from the deep depths provided the high pressure air within his body after exhalation is properly purified before being re-inhaled. The operative inhales and exhales normally from. and into the inflatable bag, 15. Exhaled air passes through rubber mouthpiece 51 and thence to valve chamber 64 where it lifts exhalation disc valve 67 from its seat, and is thence directed by upper partition 61 in the metal casing 49 to the flexible exhalation tube 47 from which it flows into inflatable bag 15. In halations are drawn from the inflatable bag 15 by inhaling through the rubber mouthpiece 51, the inhalation closing the exhalation valve 6'7 and raising the inhalation valve 66 from its seat, permitting the atmosphere within the inflatable bag 15 to be drawn through chemical container via flexible inhalation tube 46.

In passing through chemical container 16 any excess percentage of carbon dioxide that may have been built up in breathing bag 15 by exhalations of the operator is absorbed by the chemical, preferably sodalime, packed between non-corrosive screens 22 and 23 of proper mesh within container 16.

As heretofore mentioned previous apparatus for supplying air to persons when submerged in water have been. so designed as to require the operator's exhalations to flrst pass through chemicals to absorb the carbon dioxide thus ridding the respired air of carbon dioxide before it enters the reservoir. As previously alluded to in the specification such a circulatory system is erroneous in principle because it offers increased resistance to breathing. By employing a circulatory system, the reverse of the one previously used, we have obtained substantially normal respiratory conditions and other advantages which will be pointed out.

In order to fully understand the great advantages attendant upon the reversal .of the usual circulatory system, it is necessaryto analyze each step thereof.

In the phrase "resistance to breathing" the term resistance has a slightly difl'erent signiflcance than that in which it is usually employed. To exhale against a high pressure is obviously to encounter a resistance to breathing, but to inhale from a region of high pressure requires unusual muscular eflort and is thus also in,ef fect a resistance to normal breathing; similarly to exhale into a partial vacuum or inhale therefrom requires unusual muscular effort, is tiring upon the operator and is therefore in effect a resistance to breathing. It is thus apparent that the term resistance to breathing indicates a departure from the normal respiratory conditions.

With this in mind, the steps of the circulatory system formally used will be analyzed and then compared to the steps in the circulatory system of our invention.

The operator, in the circulatory system heretofore in use exhales against a pressure differential due to a diflerence in level and also against the internal resistance of the chemical container. There are thus two factors with a cumulative effect producing resistance to exhalations. The operator inhales with the pressure difierential due to difference in level tending to force the air into his mouth. Thus on neither inhalation or ex halation does the operator have normal respiratory conditions, with the result that he tires quickly and also the greatly increased resistance to exhalations due to the above mentioned cumulative eifect has the tendency to cause the operator to blow his mouthpiece from his mouth.

in the circulatory system of our invention exhalation is resisted by the pressure differential alone, instead of by the pressure differential plus the resistance of the canister. Exhalation in the circulatory system of our invention is therefore more nearly normal as resistance is reduced by an amount equal to the resistance of the canister or approximately one-half.

"in the circulatory system oi our invention, upon inhalation the resistance of the canister is neutralized by the pressure differential so that inhalations are normal. It can thus be seen that the circulatory system of our invention but one departure is made from the normal respiratory conditions, and that to a comparatively small degree on exhalation. I'he muscles of the human respiratory system are such that they do not tire so easily upon encountering unusual respiratory conditions on exhalation as they do when encountering unusual conditions on inhalation.

The immediate result is that an operator can breath indefinitely without tiring using the circulatory system of ou invention whereas he would tire rapidly when using the circulatory system previously employed.

In addition to the above enumerated advantages, the position of the canister as in the circulatory system of our invention permits the excess of carbon dioxide to be partially removed by means of the relief valve 56. The carbon dioxide being heavier than air will settle to the bottom of the inflatable bag 15 and hence is first to escape through relief valve 56. In this way excess carbon dioxide is partially eliminated from the circulatory system of our invention instead of being retained therein as in previously employed circulatory systems. This, of course, has the direct result of permitting a smaller canister with the attendant advantages of weight and in the apparatus to overcome resistance to the operators normal respirations are correlated with and directly dependent upon the maintenance of a constant and proper equilibrium between the external pressure of the surrounding water at the inflatable bag and the operators mouth, chest, and lung levels and the internal pressure of the atmosphere within the inflatable bag and the operators body.

It will be further understood that such equilibrium between these external and internal pressuresis also correlated with and dependent upon the method for maintaining the apparatus at a proper and constant volumetric capacity at all times, irrespective of changes in surrounding water pressures. Also that the method of maintaining this constant volumetric capacity is, in turn, correlated with the method of maintaining the apparatus at a proper and constant buoyancy to permit the operator to so regulate his ascent as to accomplish his own decompression without assistance from the surface, and thereby eliminate the well-known dangers of caisson disease which might otherwise be contracted.

As previously stated, in apparatus heretofore designed for this purpose, the inflatable reservoir is supplied with atmosphere from an oxygen or compressed air flask which is rigidly connected to and forms an intergral part of the apparatus.

The flow of this atmosphere from this source being constant regardless of the changing external pressures and the operators respiratory requirements. Under such conditions the air reservoir is initially inflated to an external pressure slightly in excess of the pressure of the surrounding water. Upon the operators ascent the pressure of the surrounding water decreases, causing an expansion of the atmosphere within the reservoir, which in conjunction with the air continuously flowing into the reservoir from the attached compressed air or oxygen flasks creates an excess pressure within the inflatable members of the apparatus. This excess pressure not only destroys the equilibrium which it is necessary to maintain between the changing water pressures and the air pressure within the operators body, but increases the water displacement of the inflatable members, thereby causing a corresponding increase in buoyancy, the effects of which have already been described in the foregoing.

With the present apparatus the constant and proper equilibrium between the varying external pressure of the surrounding water and the internal air pressure within the inflatable bag and i within the operators body is maintained in the following manner:

The respirable atmosphere is obtained with an initial inflation of the bag preferably from an extraneous source such as the compressed air or oxygen tanks in the submarine, but, in the absence of these, from the small detachable bottle 35 or if necessary from the lungs of the operator himself. When the operator emerges from the submarine with the apparatus the pressure of the atmosphere within the inflatable bag and within his body is approximately the same as the external pressure exerted on the bag and his body by the surrounding water in which he is standing.

On his ascent this external pressure decreases in ratio with the decrease in depth, with the result that the internal pressure of the atmosphere within the bag and within his lungs becomes greater than the external pressure of the surrounding water. Under these circumstances the bag being inflatable and flexible, will expand beyond its normal size and the air in the lungs of the operator will expand faster than it can be exhausted unless proper preventative means are provided. In the present apparatus this is prevented by means of relief valve 56.

The operation of this valve is automatically controlled by the external pressure exerted by the surrounding water. When the air pressure within the valve exceeds the external pressure of the surrounding water, the valve automatically opens and permits the escape of air until the air pressure within the bag reduces to that of the external pressure exerted by the surrounding water. The proper equilibrium between varying external pressures of .the surrounding water and the internal pressure of the inflatable bag and the operators body is maintained by keeping the extent of inflation of the bag and thus its volumetric capacity substantially constant. This maintained constant volume requires an internal pressure within the bag slightly in excess of the external pressure exerted by the surrounding water, and to maintain it regardless of varying external pressures the relief valve is extended by means of its attached hose 55 to a proper distance below the bottom of the breathing bag. In the valve the point of escape of excess air coincides with the point of application of the surrounding pressure. This feature prevents entrance of water into the bag which would otherwise occur.

As previously mentioned, the pressure exerted by sea water increases approximately one-half poundfor every foot increase in depth; the distance to which the relief valve extends below the inflatable bag is therefore such that the increase in external pressure of the water at this point over the pressure at the level of the breathing bag is equal tothe constant internal pressure which must be maintained within the bag. This difference between the external pressures at the bag level and the relief valve level remains constant irrespective of depth. Consequently any increase in pressure or expansion of the air within the bag over the necessary constant difference results in its escape through relief valve 56, which remains open until the air or atmosphere in the bag is again at the required pressure at the depth for the time being,'at which point relief valve 56 is automatically closed by the compensating pressure of the surrounding sea water.

It will be understood that while the drawings show relief valve 56 connected near the bottom of the inflatable bag, it may be connected at any point in the circulatory system below the mica disc valves 66, 6'7, provided-it is extended from such point to a proper depth below the bottom of the inflatable bag by its connecting hose 55, although such relocating will necessitate the use of a chemical container of greater capacity than the one when the relief valve is located at the bottom of the bag.

By maintaining a constant equilibrium between external and internal forces, thereby permitting the operators normal respiration at all times, the buoyancy of the apparatus is also maintained at a predetermined constant irrespective of varying external pressures exerted upon it. This predetermined constant is such that the operator without undue effort, can regulate his ascent to conform with the rate required for proper decompression from abnormal pressures,

The apparatus insures positive connection at all times between the operators respiratory system and the apparatus, first, by the maintenance of a constant equilibrium between internal and external pressures and maintenance of a constant buoyancy, and second, by a specially designed mouth piece 51.

The advantages of this mouthpiece are, that the holding power of all of the teeth plus that afforded by the suction of the dome '77 against the roof of the mouth is utilized without strain or undue effort on the part of the operator, and without interference with his respiration or the normal position of his tongue, thus insuring against the mouthpiece blowing out under any conditions; also the necessity of external face and head straps for holding the mouthpiece in place is eliminated, and the mouthpiece can be readily removed from the mouth when the oprator reaches the surface.

After the operator reaches the surface the apparatus acts as a life preserver to keep him afloat by virtue of its continued buoyancy, which is maintained by closing the cut-off valve 50 at the mouthpiece.

This prevents any escape of air through the mouthpiece. The only other outlet of the circulatory system is the relief valve 56, and as previously described, the functions of this valve are such that only air in excess of that producing normal inflation escapes from the bag.

In order to determine how long a person shall stop at certain stops, the stop indicators 86, which may be knots in the line, or cork or wooden stops, are placed conveniently ten feet apart, and the period of rest for proper decompression for the particular stop is determined from tables for that purpose.

For example, if a person has to ascend from a depth of 300 feet, on emerging from an escape look at that depth he can ascend at once to feet below the surface and rest there during twelve breaths, he then ascends to the stops, stopping at each one for a period of time. At the 60 foot depth for twenty-four breaths, at the 50 foot depth for sixty breaths, at the 40 foot depth for seventy-five breaths, at the 20 and 10 foot depths for thirty breaths each, and then to the surface, where the bag will keep them afloat an indefinite time after the valve 50 is closed.

While a particular method of submarine escape has been referred to in order to clearly describe the apparatus, and for this purpose, as a preference, an extraneous source of respirable atmosphere for initially charging the apparatus has been described, it will be understood that the apparatus is equally applicable to uses under all conditions allied to those herein described.

It will be further understood that the extraneous source of respirable atmosphere desirable for initially charging the apparatus need not be limited to oxygen or compressed air tanks on the vessels, but may be derived from one or more flasks 35 of compressed respirable atmosphere stored in a belt, or from the lungs of the operator.

It will be further understood that the use of such an alternative source of supply of respirable atmosphere in no way changes the principle of operation or functions of the apparatus by virtue of the fact that such flask or flasks do not form an integral part of the apparatus, but may be readily withdrawn from the belt and thrown away after the initial charging of the inflatable bag.

Torthose skilled in the art to which our invention relates many changes in construction and breathing bag, a carbon dioxide absorbent con-- tainer therein, a valve on the bottom of said bag to automatically vent the interior of the bag thereby reducing the pressure in said bag and the body of the operator to correspond to the variable external pressures of the surrounding water, means for supplying respirable air from said bag and container to the operator, and means for carrying exhaled atmosphere from the operator directly into said bag.

2. In an underwater breathing apparatus, a breathing bag, a container in said bag, means in said container for purifying atmosphere under pressure-to normal respiratory condition, a mouth piece, means between said mouthpiece and container for conveying respirable atmosphere to an operator, means for supplying exhaled atmosphere from said mouthpiece to said bag, and automatic means on the bottom of said bag for decreasing the pressure in said bag and the body of the operator to correspond to the variable pressures of the surrounding water.

3. In an underwater breathing apparatus,-a breathing bag, a carbon dioxide absorbent container therein, a mouthpiece, breathing tubes connecting said mouthpiece to said container and said bag, automatic means for regulating the flow of atmosphere under pressure-from said container to said mouthpiece and from said mouthpiece to said bag, and automatic means connected with the bottom of said bag for decreasing the pressure in said bag and the body of the operator to correspond to the variable pressures of the surrounding water.

4. In an underwater breathing apparatus, a breathing bag, means in said bag for keeping atmosphere under pressure in a normal respiratory condition, a mouthpiece, a tube connecting said normal respirable atmospheric means to said mouthpiece, a tube from said mouthpiece to said bag for exhaled atmosphere, means regulating the flow of atmosphere under pressure going through said tubes, automatic means, on the bottom of the bag for decreasing the pressure in said bag and the body of the operator to correspond to the variable pressures of the surrounding water, and means for attaching said apparatus to an operator,

5. In an underwater breathing apparatus, a breathing bag, means in said bag for keeping atmosphere in a normal respiratory condition, a

mouthpiece, a tube connecting said normal the operator's mouth, and means for attaching said apparatus to an operator.

6. In an underwater breathing apparatus, a

' atmosphere breathing bag, means in said bag for maintaining atmosphere in normal respiratory condition, means for supplying atmosphere from said container to an operator, means for returning exhaled atmosphere from the operator directly to said bag, a vent for automatically decreasing the pressure in said bag and the body of the operator to correspond to the variable pressures of the surrounding water, and means securing said vent to the bottom of said bag and adapted for adjusting the position of the vent.

'7. In a breathing apparatus, a breathing bag, means in said bag for maintaining atmosphere in.normal respiratory condition, means for supplying atmosphere from said container to an operator, means for returning exhaled atmosphere from the operator to said bag, a vent for automatically varying the pressure in said bag, and a flexible hose connecting said vent to said bag and means for adjusting the effective length of said hose.

8. In an under-water breathing apparatus, a breathing bag, means in said bag for maintaining in normal respiratory condition, means for supplying atmosphere from said con-= tainer to an operator, means for returning exhaled atmospherefrom the operator to said bag, a vent for automatically varying the pressure in said bag, said vent consisting of a slit, hollow rubber body held closed by external water pressure above the pressure in said bag, and an adjustable hose connecting said vent with said bag.

9. In an under-water breathing apparatus for ascending from depths, in combination a breathing bag a container secured to said bag, means in said container for reducing atmosphere to a normal respiratory condition, a non-return inflating .valve secured to said bag, means for supplying atmosphere from said container to an operator, means for returning exhaled atmosphere to said bag, an air or oxygen tank detachably secured to said valve means for connecting and disconnecting said tank to said non-return inflating valve under water without permitting the admission of water to said apparatus and a vent on the bottom of said bag for varying the pressure" inthe bag and in the body of the operator to. cor,- respond to the variable pressures of the surrounding water.

10. In an under-water breathing apparatus, a breathing bag, means in said bag for purifying atmosphere to normal respiratory condition, a mouthpiece, a tube connecting said purifying means to said mouthpiece, a tube from said mouthpiece to said bag for exhaled atmosphere, J

a vent secured to the bottom of the bag for reducing the pressure in said bag and in the body of the operator to correspond to the carrying pressures of the surrounding water, and means regulating the atmosphere going through said tubes, said means consisting in a valve chamber and flutter valves inclined to each other to direct air to and from an operator.

11. In a breathing apparatus, a breathing bag, means in said bag for keeping atmosphere in a normal respiratory condition, a mouthpiece, a tube connecting said normal respirable atmospheric means to said mouthpiece, a tube from said mouthpiece to said bag for exhaled atmosphere, means regulating the atmosphere going through said tubes, automatic means secured to and extending below the bottom of the bag for decreasing the pressure in said bag, and means for attaching said apparatus to an operator, said means consisting of straps, and straps having spring clamps for clamping to the trousers of an operator and to said first mentioned straps.

12. In an under-water breathing apparatus, a breathing bag, means in said bag for maintaining atmosphere in normal respiratory condition, and means for supplying an operator with respirable atmosphere from said bag and returning exhaled atmosphere to said bag comprising a mouthpiece having an external lip engaging plate, an internal lip engaging plate, and a continuous flange for extending between all the teeth, said flange having a combined intake and exhaust part therein, and tubes connecting said mouthpiece to said bag.

13. In an under-Water breathing apparatus, a breathing bag, means in said bag for maintaining atmosphere in normal respiratory condition, and means for supplying an operator with respirable atmosphere. from said bag and returning exhaled atmosphere to said bag comprising a mouthpiece having an external lip engaging plate, an internal lip engaging plate, teeth engaging means, and a dome for fitting the roof of a mouth behind the front teeth, and tubes connecting said mouthpiece to said bag.

14. In an under-water breathing apparatus, a breathing bag, a container in said bag, means in said container for keeping atmosphere in normal respiratory condition, and a mouthpiece comprising an external lip engaging plate, an internal lip engaging plate, a continuous flange tapering in thickness toward the end thereof for extending between all the teeth and a dome for fitting a mouth behind the front teeth.

15. In an under-water breathing apparatus, a breathing bag, a container in said bag, means in said container for keeping atmosphere in normal respiratory condition, and a mouthpiece comprising an external lip engaging plate, an internal lip engaging plate, a continuous flange tapering in thickness toward the end .thereof for extending between all the teet and a dome for fitting a mouth behind the iron teeth, and a tube connecting said container and said mouthpiece and a second tube connecting said mouthpiece and said bag for returning exhaled atmosphere.

16. In an under-water breathing apparatus, a breathing bag, a mouthpiece, a tube connecting said bag and said mouthpiece for returning exhaled atmosphere to said bag, means varying the pressure in said bag, a chemical container within the bag secured to the upper part thereof for maintaining atmosphere in normal respiratory condition, said container having a screen over its lower open end, a second screen reasonably placed from the upper end, a filling aperture intermediate said screens, a cap removably placed in said aperture, an outlet nipple on the container having a screen in, its lower end, and a second tube secured to said nipple and connected to said mouthpiece for supplying respiratory atmosphere.

17. In an under-water-breathing apparatus, a

breathing bag, a container secured to the upper portion of said bag, means in said container for reducing air to normal respiratory condition, a mouthpiece, breathing tubes leading from said container and said bagto said mouthpiece, a valve chamber having flutter valves therein inclined to each other to direct air to and from said mouthpiece interposed between said bag and said mouthpiece, a shut off valve for said tubes, an automatic vent valve for maintaining the proper respiratory pressure in said bag, and adjustable hose connectingsaid vent valve to the bottom of said bag, a nasal clip for cutting off nasal respiration, and straps and clips secured to said bag for attaching the apparatus to an operator.

18. In an underwater breathing apparatus, a breathing bag, means in said bag for maintaining atmosphere in normal respiratory condition,

means supplying atmosphere from said last stated means to an operator, means for returning exhaled atmosphere from the operator to said bag, means for automatically regulating atmosphere drawn through said bag, and a vent on the bottom of said bag and extending below said bag for automatically decreasing the pressure in said bag to correspond to the reduction in external pressure due to varying depths whereby the time during which the apparatus will support normal respiration increases with the increase in depth at which the apparatus is used.

19. In an underwater breathing apparatus, a breathing bag, means for supplying respirable atmosphere from the bag to an operator, and an automatic valve secured to and extending below the bottom of said bag to automatically vent the interior of the bag to reduce the pressure in the bag and the body of the operator to correspond to the variable external pressures of the surrounding water.

20. In a mouthpiece for a breathing apparatus, an external lip engaging plate, an internal lip engaging plate and a continuous flange adapted to extend between all the teeth, said flange having an air passage therein.

21. In a mouthpiece for a breathing apparatus, an external lip engaging plate, an internal lip engaging plate, means adapted to lie against the lingual surfaces of the teeth, and a dome spaced from said second plate to fit the operators mouth.

22. In an underwater breathing apparatus, a breathing bag, a mouthpiece, means for supplying respirable atmosphere from the bag through said mouthpiece to an operator, an automatic valve secured to and extending below the bottom of said bag to vent the interior thereof so as to reduce the pressure in the bag and the body of the operator to correspond to the pressures of the surrounding water, means for closing said mouthpiece, and means for closing the vent valve whereby the apparatus can be used as a float on the surface of the water.

23. In an underwater breathing apparatus, a breathing bag, a chemical container secured within said bag, said container having an outlet nipple, a screen in the lower end of said nipple, and means adapted to by-pass moisture and foreign matter mounted on said screen. thereby insuring the passage of air from the container, a mouthpiece and breathing tubes connecting said mouthpiece to the nipple of said container and to the bag.

24. In an underwater breathing apparatus, a breathing bag, a chemical container secured within said bag, said container having an' outlet nipple, a screen in the lower end of said nipple, and a removable conical screen positioned on said screen to insure the passage of air from the container, a mouthpiece and breathing tubes connecting said mouthpiece to the nipple of said container and to the bag.

CHARLES E. MOMSEN.

CLARENCE L. TIBBALS. FRANK M. HOBSON.

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