US 3692026 A
A conduit connects a mouthpiece with an exhalation bag and the inlet of a canister containing a bed of oxygen producing and carbon dioxide absorbing chemical. The bag is provided with a normally closed exhaust valve. Another conduit connects the outlet of the canister with an inhalation bag and the mouthpiece. The outlet of a pressure tank containing a mixture of oxygen and a diluting gas is connected by a demand valve with the inlet conduit.
Description (OCR text may contain errors)
United States Patent Tepper et a1.
 UNDERWATER BREATHING 1 Sept. 19, 1972 3,148,034 9/1964 Bovard et a1. ..23/281 APPARATUS 3,402,711 9/ 1968 Emerson ..128/ 142.2  Inventors: Frederick Tapper, owings Mills, 3,403,981 10/1968 Lemcke et al ..23/281 21% Mausteller Evans FOREIGN PATENTS OR APPLICATIONS 1 y, a. 461,873 7/1928 Germany ..128/l91 R [731 Asslgnee= 5 f Al'plla'lces Company 6,966 12/1910 Great Britain ..128/191 R 1 s urg a.
 Fil d; on, 20, 1969 Primary Examiner-Dalton L. Truluck Assistant Examiner-J. B. Mitchell l2] I AWL 8676l0 AnorneyBrown, Murray, Flick & Peckham  U.S.Cl ...128/l42.2 ABSTRACT  Int. Cl. ..A62b 7/04 A conduit connects a mouth p1ece with an exhalat1on  z bag and the inlet of a canister containing a bed of ox- 1 I ygen producing and carbon dioxide absorbing chemical. The bag is provided with a normally closed ex-  References C'ted haust valve. Another conduit connects the outlet of UNITED STATES TENTS the canister with an inhalation bag and the mouthpIece. The outlet of a pressure tank contalnmg 1;; E t-" 2 a mixture of oxygen and a diluting gas is connected by am er sen d 1 th l t d 2,906,262 9/1959 Braunstein ..12s/142.2 adema W eme 7 Claims, 1 Drawing Figure l I L 3 t /4 1 /2 wi l 2-.) 7 '9 I 5 /7 z I g 1 1 '11 i I l i 79 ii i I! 2a I l PATENTEDsEP 19 I972 INVENTOR-S LLE UNDERWATER BREATHING APPARATUS With the ever-increasing interest in undersea exploration and work there is an increasing need for better underwater breathing apparatus. Cost, weight, simplicity, reliability and capability of long periods of uninterrupted use are all factors to be considered. There are several different underwater breathing systems, but for working at considerable depths the semi-closed system is one of the best. However, apparatus of this kind used heretofore has been unduly complicated and expensive, and it has not allowed the diver to stay in deep water very long because of inefficient usage of breathing gases. All of this is an outgrowth of one of the basic problems in deep diving; that of oxygen poisoning. As the diver descends in the water and the water pressure increases, the oxygen partial pressure in his breathing circuit increases. When this partial pressure reaches around 1.5 to 2.0 atmospheres, it is likely that convulsions from oxygen toxicity may occur, and they may be followed by death. Therefore, the problem is to maintain a safe oxygen partial pressure, regardless of the depth at which the diver works, without reducing a sufficient supply of oxygen for supporting him while he is working.
It is among the objects of this invention to provide underwater breathing apparatus which is self-contained and can be worn by a diver, which is relatively simple and compact, which can be used safely at considerable depths, which automatically compensates for variations in depths, which provides sufficient oxygen without oxygen poisoning, and which is economical to use.
The preferred embodiment of the invention is illustrated in the accompanying drawing, in which the single FIGURE is a perspective view, with parts broken away, of the breathing apparatus carried by a diver.
Referring to, the drawings, a canister l, preferably rectangular, is provided withstraps 2 for carrying it on the back of a diver. Inside the canister there are two laterally spaced partitions 3 and 4 spaced a short distance from the ends of the canister to form end chambers 5 and 6 having openings 7 and 8 at their upper'ends. Each partition is formed from a filterand a screen, and the relatively large area between the partitions is filled with a granular bed 9 of a chemical that will produce oxygen andabsorb carbon dioxide when the user of this apparatus exhales into the chemical. The most suitable chemical is K0,, although there are other alkali metal superoxides that could be used, such as sodium superoxide. Likewise, lithium peroxide and sodium peroxide are satisfactory. System economy is achieved through the use of such chemicals, which produce oxygen proportionally to the rate of respiratory exchange. The moisture in the exhaled breath ac-' tivates the chemical to generate oxygen almost in balance with oxygen consumption by the diver.
A conventional mouthpiece 11, which also may be in the form of a mask, is connected by flexible inhalation and exhalation hoses 12 and 13 with the openings in the top of the canister end chambers. The customary check valves are provided to permit flow in only one direction. The exhalation hose is provided with a fitting 14 that puts it in communication with an exhalation breathing bag 15 hanging over the chest of the diver. This bag is provided with a normally closed exhaust check valve 16. The other hose is provided with a similar fitting l7 connecting it with an inhalation breathing bag 18. Extending downwardly from each of the chamber openings 7 and 8 is a. rigid tube 19 that is open at its lower end, which preferably is located in about the center of the chamber. Therefore, regardless of whether the diver is upright or head down, the open ends of tubes 19 should be above any water that may have entered the canister chambers. The open end of each tube may open into the top of a small cup 20, the open end of which faces the adjacent screen and filter. If desired, only one breathing bag could be used.
When the diver exhales into the canister, the moisture in his breath causes the chemical to generate oxygen. At the same time, it removes carbon dioxide. With chemicals such as K0,, there is an opportunity for more oxygen to be generated than is consumed. During inhalation the purified air, plus the generated oxygen, is breathed. A small portion of the exhaled breath will escape from this semi-closed circuit through the exhaust valve 16. This valve is loaded sufficiently to permit the breathing bags to inflate, but otherwise normally is held shut by the pressure of the surrounding water.
With the apparatus described thus far, the partial pressure of the oxygen in the breathing circuit is likely to increase as the diver descends through the water and the ambient pressure increases. As the oxygen partial pressure increases, the danger of oxygen toxicity increases, with fatal results if the diver goesdeep enough. This dangerous conditionis prevented, according to this invention,by incorporating in the apparatus a pressure bottle or tank 22 containing a diluting gas, preferably helium. A secondary purpose of this supplementary gas is to pressure balance the system to compensate for increases in depth. This tank can be attached to the bottom of the canister and is provided with an outletvalve 23. The outlet valve is connected through a demand regulator or valve 24 with the inlet hose. This connection can be made by connecting the outlet of the demand valve, by means of a tube 25, with canister chamber 6, to which the inlet hose is connected.
To provide a small supply of oxygen that can sustain the diver even if the primary oxygen source fails, the gas in the tank contains a lowconoentration of oxygen, depending upon the depth at which the diver is to work. For example, the mixture may contain only about 3 percent oxygen for a depth of around a couple hundred feet. Even less oxygen is used when the diver is to go to a materially greater depth. Every time the diver inhales he causes a reduction in pressure in the inhalation bag 18 and the related canister chamber 6 and this causes the demand regulator to open and allow a pulse of the gas mixture from the tank to be added to the breathing system. The demand regulator therefore will feed in the mixture in a quantity that is approximately proportional to the work rate. As the diver descends, the percentage of oxygen in the breathing gas flowing through the breathing circuit decreases, due to the diluting effect of the added gas mixture and the continuous dumping of excess oxygen and exhaled air through the exhaust valve, but the actual amount of oxygen within the circuit remains relatively constant so that the amount of oxygen inhaled by the diver with each breath stays substantially the same. The reduction in the percentage of oxygen, however, keeps the partial oxygen pressure from building up toward the danger point.
Another feature of the invention is that there is a bypass 27 for the gas mixture around the demand valve, the bypass being controlled by a manually operated needle valve 28. This valve may be set to allow a continuous trickle of gas from the tank into chamber 6 of the canister so that there will always be a minimum supply of oxygen to the diver even if the chemical fails to produce oxygen. This bypass also allows the diver to adjust the size of the breathing bags by inflating them more or less.
As the diver ascends toward the surface of the water, the water pressure tending to hold the exhaust valve 16 closed will decrease and this will allow more and more of the air in the breathing circuit to escape from the system so that the percentage of oxygen in the circuit will gradually rise until it reaches normal at sea level.
The oxygen composition used at depth would be substantially below the 20 percent necessary to support the diver at sea level. Oxygen could be added during ascent by means of another bottle (not shown). However, it is preferred to turn off the helium purge system and allow the normal oxygen overproduction of the chemical to satisfy the higher percentage of oxygen necessary at shallow depths.
l. Underwater breathing apparatus comprising a canister having an inlet and an outlet, a bed of oxygen producing and carbon dioxide absorbing chemical in the canister between said inlet and outlet and constituting the primary oxygen source, a mouthpiece, an exhalation conduit connecting the mouthpiece with said canister inlet, an inhalation conduit connecting said canister outlet with said mouthpiece, a breathing bag connected with one of said conduits and provided with a normally closed exhaust check valve, a pressure tank containing a mixture of oxygen and a diluting gas and having an outlet, and means including a demand valve connecting the tank outlet with said inhalation conduit every time inhalation reduces the pressure in the inhalation conduit.
2. Underwater breathing apparatus according to claim 1, including manually adjustable means bypassing said demand valve for continually delivering a restricted stream of said mixture from the tank to said inlet conduit.
3. Underwater breathing apparatus according to claim 1, in which said chemical is spaced from the opposite ends of the canister to form horizontally spaced end chambers therein, and said canister inlet opens into the top of one chamber and said outlet opens into the top of the other chamber.
4. Underwater breathing apparatus according to claim 3, in which said conduits extend down into said chambers and are provided with openings in their lower ends located at about the center of the chambers.
5. Underwater breathing apparatus according to claim 3, in which the outlet of said demand valve communicates with the canister chamber provided with said canister outlet.
6. Underwater breathing apparatus according to claim 1, in which said bag is an exhalation bag connected with the exhalation conduit.
7. Underwater breathing apparatus according to claim 1, in which said bag is an exhalation bag connected with the exhalation conduit, said apparatus including an inhalation bag connected with the inhalation i. condut