Abstract: A swim and skin-dive snorkel for providing positive end-expiratory pressure for pressure-balanced exhalation. The snorkel may include inhalation and exhalation conduits. Air can be exhaled into a chamber and released when exhalation pressure within the chamber exceeds a threshold pressure. The threshold pressure that must be overcome to achieve exhalation may be balanced against the compressive forces of the ambient water pressure acting against the user's chest and lungs, which may greatly reduce the resting expiratory flow rate, the minute respiratory rate, and therefore the overall work of breathing. The exhalation pressure may be linearly matched to the ambient water pressure as a function of dive depth, thereby discouraging exhalation while diving. A purge valve may also be placed at the lower aspect of the snorkel.

Abstract: Aircraft passengers who require a therapeutic oxygen supply independently of the prevailing cabin pressure, as distinguished from an emergency oxygen supply that depends on an inadequate cabin pressure, can breath therapeutic oxygen and/or emergency oxygen depending on the situation, through the same therapeutic oxygen masks. For this purpose a control accessible to the crew is used to connect a therapeutic oxygen supply to the emergency oxygen distribution system of the aircraft, whereby the source of oxygen is used either partially for therapeutic purposes or fully for emergency purposes.

Abstract: A gas regulator includes a delivery valve assembly having a delivery outlet and a delivery valve member engageable with the delivery outlet for controlling flow of a gas from a gas source. A timing gas chamber receives gas from the gas source. Gas pressure within the timing gas chamber controls the operation of the delivery valve member. An adjustment system controls the amount of time required for the gas to fill the timing gas chamber so as to control the length of time that the delivery valve assembly is opened to conserve gas. In other embodiments, a capacity adjustment system can adjust the capacity of a gas reservoir system.

Abstract: This invention relates to protective hoods, and in particular personal protective hoods which surround an individual's head and protects the individual from contact with Chemical-Biological-Radiological-Nuclear (CBRN), smoke, noxious fumes, and products of combustion, such as carbon monoxide. The protective hoods contain neck dams that seal against a person's neck and are formed from thermoplastic elastomers or polyolefins.

Abstract: A closure device of a second-stage regulator for scuba divers, the regulator comprising a regulator body with an inlet conduit for connection to a first-stage regulator which supplies a breathable gaseous mixture at relatively constant pressure, an outlet conduit for connection to a mouthpiece of the users, and an opening closed by a deformable diaphragm. The device comprises a locking frame connected in an articulated manner or jointedly to the regulator body to lock the diaphragm in the opening, and a member for fastening the frame to the regulator body.

Abstract: A mask adapted to be attached to a user's face is disclosed. The mask comprises a body and a gas connection structure. The body is formed with an inner space which is defined along with the user's face. The inner space allows the user to breathe through the nose. The gas connection structure connects to the body so that the inner space is connectable with the ambient air via the gas connection structure. Thereby, the user is capable of breathing through his/her nose to drive the ambient air into the inner space and reduce the moisture formed in the inner space.

Abstract: The combination noise suppression and breathing respirator of the present invention includes a face mask of the snorkel or diving type, the facemask sealing against the face of the user around the nose, cheeks, eyes and forehead of the wearer. The facemask has a nosepiece having an exhalation flap check valve for exhalation by the user. Each side of the face mask has a one-way inlet valve at a connection which connects with rearward extending dual use air channel and straps. A noise suppression and air filter module is worn over each ear of the user and is attached to respective dual use air channel and straps. Head bands extend around the back of the wearer's head between air filter modules an adjustably connected by buckles thereto.

Abstract: A valve assembly (20) for a respirator comprises a valve body (25) having a valve outlet portion and a valve inlet portion which together define a valve cavity (30) for a valve mechanism (24) permitting gas flow from the valve inlet portion to the valve portion member, an air purge means comprising a purge inlet, connectable to an air pressure supply means, an air purge outlet (27) and an air deflection means (28) in which the deflection means is spatially arranged relative to the valve mechanism and purge outlet so that, in use, air exiting the purge outlet and incident the air deflection means provides a curtain of air over the valve mechanism.

Abstract: The present invention concerns a valve unit for a rebreather apparatus that recycles gas exhaled by a user. The valve unit includes a housing 5 with a first port for communication with a respiratory system of the user and a first inlet port 9 for breathable gas in said housing, a first exit port for exhausting gas from said housing into a flow channel, at least one separate second exit port 12 for exhausting gas form said housing 5 into an ambient environment, a second inlet port 13 for breathable gas connected to an open loop inlet valve 6 in said housing 5, and a valve body 4 in said housing 5 forming a valve for switching between two operating modes. The valve body 4 is formed as a barrel or cylinder with valve openings sealing against the housing 5, where the valve body 4 forms an internal cavity 18, alone or in combination with the housing 5, in connection with the port 10 for communication with a user. The valve 6 has an outlet in said cavity 18.

Abstract: An aerosol generation device comprising an oscillatable membrane (1) for the nebulization of a liquid, having a first curved region (11), and an oscillation generating device (2, 3) by which the membrane can be caused to oscillate such that a liquid disposed on one side of the membrane is nebulized through the oscillating membrane and is present on the other side of the membrane as an aerosol. The membrane has at least a second region (12) which is surrounded by the first region (11). The first region (11) and the second region (12) have different curvatures (1/r1, 1/r2).

Abstract: A powered respiration comprising, an air supplying unit and a filter equipped to a face piece part of said powered respiration, wherein an electric fan, a motor and a battery are installed in said air supplying unit.

Abstract: A valve mounted on a dive mask is disclosed. The mask has a closed window frame, a soft skirt extending rearward from the window frame for defining a space between itself and the face of a diver wearing the mask, and one or two windows defined by the window frame. The valve is flexible, tubular and has a first opening at one end in communicating with the space, and a second opening at the other end. The second opening is blocked in an inoperative position and is adapted to open to expel water or air therethrough by increasing pressure in the space or by pressing both sides of the valve.

Abstract: A respirator includes a first chamber, a second chamber, and a separator that separates the first chamber and the second chamber. A filtration system includes an inhale valve that only allows air to enter the respirator and an exhale valve that only allows air to exit the respirator. The system can be reversed so that the inhale valve and exhale valve may be positioned on either the first or second chamber. A replaceable filter can be provided that includes a supply canister including a supply of filter material, a take-up canister that receives used filter material, and a path between the supply canister and the take-up canister that guides the filter material across the respirator's inhale valve, exhale valve, or both the inhale and exhale valves.

Abstract: An on-board oxygen generating system is provided, which includes an air supply duct, a breathing gas duct, and an oxygen generator fluidly coupled between the air supply duct and the breathing gas duct. The oxygen generator is configured to enrich the oxygen content of air flowing from the air supply duct to the breathing gas duct. A drain valve assembly is fluidly coupled to the air supply duct and configured to move between: (i) an open position wherein condensation may drain from the air supply duct, and (ii) a closed position.

Abstract: A socket part actuated without pressure for a fluid coupling is provided with means, which mechanically seal, to a large extent, the insertion space of a plug against the penetration of foreign matter. In addition, a throttling device is provided, which practically does not obstruct the fluid connection for an inserted plug, while a high flow resistance is produced for a plug that has been pulled out, without, however, completely blocking the flow path. The associated plug also has a sealing device in order to protect the flow channel against the penetration of particles when the plug is removed. In case the plug is connected to a compressed-air tank, this is provided with a throttling device, which practically does not obstruct flow for an inserted plug, but forms considerable flow resistance for a removed plug without completely blocking the flow.

Abstract: The invention relates to life-saving engineering. The inventive protective hood is embodied in the form of a bag comprising a sorbing-filtering insert, a sorbent container, an exhalation valve, a mouthpiece assembly and a spring element for compressing and the extending the bag. Said hood is a small-sized, has a simple structural design, provides a high protection level and is easy to use.

Abstract: An electro mechanically-assisted control system for use in a second-stage regulator. Regulator control assembly (20?), also referred to as all-electronic (AE) assembly (20?), includes an electromechanical actuator (EMA) sub-assembly (22) for controlling airflow through single air supply line (23). EMA sub-assembly (22) includes electronically controllable actuator (ECA) (34), which removably seals EMA orifice (36) in wall (30) of pilot chamber (32). ECA (34) is electrically connected with and controlled by control electronics (38). The control electronics include programmable microprocessor (40), which is electrically connected with charge and discharge electronics (42), both of which are electrically connected with power supply (44). All-electronic (AE) assembly (20?) has only an EMA sub-assembly and no mechanical actuator sub-assembly.

Abstract: A group for controlling a second-stage regulator for scuba divers. The regulator comprises a regulator body with an inlet conduit for connection to a first-stage regulator which supplies a breathable gaseous mixture at a constant pressure and an outlet conduit for connection to a mouthpiece of the user. The group comprises a first bushing defining an intermediate chamber with a bottom wall wherein a central hole is formed, a poppet loosely engaged within the hole, the end of the poppet being connected to lever means, a second bushing engaged in the first bushing and defining an inlet chamber and a third bushing engaged in the second bushing and defining a regulator seat at one of its ends. The head of the poppet engages tightly in the seat and an elastic member is provided coaxial to the poppet in the intermediate chamber for maintaining the head against the regulator seat.

Abstract: A diving mask includes a nose cover and a valve seat of a drainage mechanism having a check valve formed in the vicinity of the nose cover. The nose cover and the value seat are formed from an elastic material which is integral with a soft elastic material forming the nose cover. In the vicinity of the valve seat, an annular member formed from a plastic material plastics having a hardness and deformation-resistance both higher than those of the elastic material forming the valve seat is embedded in a bottom of the nose cover so as to extend along the valve seat.

Abstract: A device for activating a signal emitter for use in a firefighter locator system operates in conjunction with the firefighter's self-contained breathing apparatus (SCBA). The activation device includes a pressure sensor to monitor pressure on an air line that delivers air from the SCBA air tank to the SCBA air regulator. When the firefighter opens the SCBA air tank valve, pressure is sensed in the air line and the emitter is activated to transmit a signal. The signal is received by base stations that then use the signal to locate/track the signal emitter. Preferably, the activating system also includes a user operated reset button(s) and a shutoff circuit to allow the user to stop transmission of the signal by the signal emitter. The shutoff circuit is designed to stop transmission of the signal only after the air line has been depressurized and the reset button(s) is depressed.

Abstract: A protective breathing hood comprising a hood made of a stretchable fire resistant material and which is also impermeable to gases and biologic material. The hood is sized and shaped for placing over a head of a user in an airtight manner with an opening of the hood scalingly engaging a neck portion of the user. At least a visor portion of the hood is transparent and a pair of respiratory units are disposed offset with respect to the nose location. Each respiratory unit comprises a housing formed with an inhalation flow path accommodating activated charcoal particles, and an exhalation flow path fitted with a one way exhaling valve, wherein at a donned position of the hood a chamber is formed at a mouth/nose location thereof.

Abstract: Regulator for underwater breathing devices including a relatively hard material box-like body having a pipe for the connection with a mouthpiece, at least one air inlet duct and at least one opening on which-it is positioned one air exhaust valve. The regulator box-like body is externally covered by at least one layer of a suitably shaped relatively soft material.

Abstract: A pressure support system having enhanced noise reduction and a valve assembly for use in pressure support system. The pressure support system includes a pressure generator having an inlet and an outlet. A first conduit defining a tortuous path is coupled between a gas source and the inlet of the pressure generator. A second conduit coupled to the outlet of the pressure generator delivers the flow of gas from the pressure generator to a patient. A valve assembly communicates gas from the second conduit to the first conduit to control the pressure or a rate of the flow of gas in the second conduit. By communicating gas from the second conduit to the first conduit, the noise associated with exhausting gas from the second conduit is muffled by the tortuous path of the first conduit.

Abstract: There is described a demand valve for a breathing apparatus with a “first breath” mechanism, wherein a demand valve is held closed by resiliently latching an operating diaphragm of the valve in a position wherein the valve is closed. The diaphragm is resiliently biased towards opening the valve, and the resilient latch is arranged to exert sufficient force so as not to be overcome by the resilient bias alone, but so as to be overcome by the combination of the resilient bias and a predetermined pressure difference across the diaphragm caused by sub-ambient pressure within the facepiece of the breathing apparatus.

Abstract: An electromechanically-assisted control system for use in a second-stage regulator. Regulator control assembly (20), also referred to as EMA assembly (20), includes a mechanical actuator sub-assembly (21) and an electromechanical actuator (EMA) sub-assembly (22) for controlling airflow through single air supply line (23). EMA sub-assembly (22) includes electronically controllable actuator (ECA) (34), which removably seals EMA orifice (36) in wall (30) of pilot chamber (32). ECA (34) is electrically connected with and controlled by control electronics (38). The control electronics include programmable microprocessor (40), which is electrically connected with charge and discharge electronics (42), both of which are electrically connected with power supply (44). Alternatively, regulator control assembly (20?), also referred to as all-electronic (AE) assembly (20?), has only an EMA sub-assembly and no mechanical actuator sub-assembly.

Abstract: A respirator (1) having a plurality of internal masks (2, 3) within an external mask (4), the inner masks (2, 3) being linked by ducts (8, 9) so as to direct the inhaled air from the outside of the mask to the oronasal area via an ocular mask. The oronasal mask (3) has a secondary valve (12) that is sprung so as to operate within the timeframe of the exhalation part of the breathing cycle, the exhaled air being ejected into the hollow outer body of the mask (4).

Abstract: A valve device, particularly for a breathing regulator for divers, including an inlet chamber which can be connected to a source of gas under super-atmospheric pressure, and an outlet chamber which is under a regulated pressure. A seating, which is movable under the influence of the super-atmospheric pressure and the regulated pressure, seals between the inlet chamber and the outlet chamber and has a through-passing passageway that interconnects the chambers. Also included is a valve body which is movably arranged in the seating such as to open and close the through-passing passageway in the seating. A servo element exerts on the valve body a force that depends on the position of the movable seating, so that varying force-influence on the valve body from the super-atmospheric pressure will be compensated for by a corresponding varying force from the servo element. This results in an essentially constant valve characteristic, while providing a mechanically simple solution at the same time.

Abstract: An exhalation valve (10) is disclosed for use with an exhalation port (14) of a respiratory circuit. The exhalation valve comprises a hermetically sealed gas chamber (20,120), a gas inlet (22,122) for supplying gas to the gas chamber, and a membrane (24,124) of flexible material that defines at least part of a wall of the gas chamber. The membrane is deformable by a change in the pressure differential between the gas within the gas chamber and the gas within the exhalation port between an inoperative configuration and an operative configuration in which the membrane restricts the flow of gas from the exhalation port to a greater extent than in said inoperative configuration. The membrane is inherently planar but is mounted within the exhalation valve such that deformation of the membrane to its operative configuration occurs substantially without increase of the surface area of the membrane.

Abstract: A snorkel for use in swimming. The snorkel includes an elongate breathing tube having an upper portion and a lower portion. A lower opening is formed in the lower portion and an upper opening is formed in the upper portion. A mouthpiece is located at the lower opening of the snorkel. A one-way valve is disposed in the lower portion and is oriented to prevent the flow of fluids into the lower portion, but to permit the flow of gases and fluids out of the lower portion. A check valve is disposed in the upper portion. The check valve includes a plate pivotable from an open position permitting airflow through the upper opening, to a closed position preventing airflow through the upper opening. A spring member contacts the plate, biasing the plate in the open position.

Abstract: An escape hood, comprising a respirator, having an air filter suitable for filtering toxic air contaminants and positioning members to retain the respirator in a respiratory path of the user; an optical lens; a expanding member, permitting hood to expand from a compact storage configuration to a usage configuration; a sealing structure, around said air filter, for preserving said filter during storage; and an unsealing mechanism, adapted to allow a user to withdraw the escape hood from a storage vessel, wherein during withdrawal, said sealing structure is automatically unsealed. An escape hood system is also provided, comprising: an array of storage vessels, each vessel being adapted to receive a sealed escape hood; a retainer, for retaining a sealed escape hood within the vessel, wherein the escape hood is unsealed during withdrawal of the escape hood from a storage vessel; and an electronic sensor for determining an occupancy of a storage vessel.

Abstract: A sub-aqua breathing system which enables a person operating underwater to breathe air from a compressed air tank supported on the water surface. The system includes a housing containing both a buoyant material and a toroidal compressed air tank connected to an air line feeding a conventional mouthpiece regulator. The air line may be coiled and stored within, or on, the housing. Preferably the housing is of discus-like shape with the buoyant material in the form of floats normally nested within the housing, but deployable radially outward to increase stability when the assembly is floating on the water surface.

Abstract: A personal hydration device providing fluid delivery to an external mouthpiece and a gas mask mouthpiece is disclosed. The personal hydration device includes a container having an exit port and an exit valve, a diverter valve, an external mouthpiece, a gas mask with a gas mask mouthpiece, and three hoses connecting these elements together. The diverter valve has a body, including one inlet and two outlets, and a spool moveably mounted within the body. The spool is moveable between a first position and a second position, and normally biased toward the first position. When in the first position, the first outlet is in an open position and fluid is delivered to the external mouthpiece. When in the second position, the first outlet is in a closed position and fluid is delivered to the gas mask mouthpiece.

Abstract: Provided are exemplary embodiments of an underwater breathing exhaust system configured to lower the exhalation, effort and to direct water adjacent an exhaust valve to reduce the likelihood of water entering the system and/or gas free flowing from the system.

Abstract: A front-worn respiratory tube without fastening assemblies namely fastening rings, hooks, buttons, clamps, sheaths or strips, includes a head-top-portion tube, a forehead-portion tube, a mouth-eyebrow-portion tube, a mouthpiece and a fish-mouth-shaped mouthpiece in a downward direction in sequence. Wherein, the aforesaid five parts are either wedge-type structures or join-type structures at three parts (from the head-top-portion tube to the forehead-portion tube, from the forehead-portion tube to the mouth-eyebrow-portion tube, and from the mouth-eyebrow-portion tube to the mouthpiece portion). The forehead-portion tube utilizes water drag force to have the tube steadily staying close to the user's head. A water-drop-shaped sectional area at the head-top-portion tube is capable of minimizing water drag. The aforesaid structure according to the invention is adaptable to head dimensions and a height of a nose tip of the user.

Abstract: A system (A) for providing single continuous dose of a gaseous heliox mixture to a patient with breathing difficulty includes a device (1) providing a constant and continuous flow of the heliox mixture, and a gas storage tank (2) for the mixture. A flow control is selectively operated to initiate flow of the heliox to the patient. It has a locking mechanism to prevent it from being turned off after the flow begins. The regulator can be reset for reuse by a service entity.

Abstract: Here is disclosed a regulator for diving free from any possibility that smooth operation of respective components might be obstructed due to the presence of impurities in the air supplied from an air cylinder. In the regulator, a tubular coupler member coupling a regulator for diving to an air hose extending from an air cylinder is provided with a filter assembly.

Abstract: A second stage regulator and a method for using the regulator is provided. The second stage regulator has a unique design to facilitate rotation of the mouthpiece about the regulator. The mouthpiece is able to be configured and reconfigured to adapt to a plurality of uses, including commercial, emergency, military and individual use. The second stage regulator also has a plurality of openings allowing for interchangability of parts. The second stage regulator has a unique ergonomic design for optimum user configuration control. The mouthpiece may be interchanged with the exhaust opening and/or blank opening, and the exhaust may be interchanged with the mouthpiece opening and/or blank opening.

Abstract: A respirator with a tidal volume-measuring device (6) between a respiration bag (8) and a patient adapter (2) provides accurate metering of the tidal volume. The device includes a first pressure-measuring device (4) and a breathing gas interruptor (5) in series sequence between the patient adapter (2) and the tidal volume-measuring device (6). A second pressure-measuring device (7) is provided between the tidal volume-measuring device (6) and the respiration bag (8). A control unit (20) is connected with the tidal volume-measuring device (6) and the pressure-measuring devices (4, 7) and sends control signals in such a way that when a predetermined tidal volume is reached, the breathing gas interrupter (5) is switched to the closed position, and that the closed position is eliminated when the pressure p2 measured with the second pressure-measuring means (7) has dropped below the pressure p1 determined with the first pressure-measuring means (4).

Abstract: A versatile underwater breathing device which comprises, a pressurized gas reservoir or tank (21), a buoyancy bladder (72), bladder inflation control means (76), a breathing regulator (32) in communication with the gas reservoir; and a flexible adaptable carrier having straps (88, 90) for securely attaching the carrier to the back of a diver, which carrier wholly contains the buoyancy bladder and the gas reservoir. The bladder inflation control means operatively couple the buoyancy bladder to the reservoir so that the bladder may be inflated and deflated to control the buoyancy of a diver, and the breathing regulator is also coupled to the gas reservoir to permit the breathing of the contained gas by the diver. The flexible carrier is adapted to be carried on the back of a wide range of differently sized divers so allowing a single piece of equipment to be used by a variety of people.

Abstract: The present invention relates to a one-way valve including an inner base, a valve plate, an outer base, and a lid incorporating on a hole under a nose cover of a diving mask. The valve plate lying just on the hole thereof forms an outward-open-only valve, thereby preventing water from penetrating inside and being able to be blown open to exclude water out of the diving mask.

Abstract: Self-contained underwater re-breathing apparatus having a breathing circuit, an injection system for adding fresh breathable gas to the breathing circuit, and an automatic control system including a microcomputer for monitoring physical parameters in the breathing circuit and controlling the feeding of breathable gas to the breathing circuit in accordance with said physical parameters. The re-breathing apparatus has a bailout system automatically activated in an emergency, where the breathing circuit is shut off, and the diver starts inhaling directly from the breathable gas supply and exaling to the environment. With the system of the invention, a part of the existing closed circuit is used for bailout, and no separate bailout circuit is provided. Therefore, there is no need to incorporate in the mouthpiece means for switching from one breathing circuit to another, and the mouthpiece can be kept smaller and simpler.

Abstract: A reducing valve, which includes a water trap, especially useful in diving.

Abstract: An apparatus for preventing or minimizing decompression illness in a scuba diver, consisting of a first safety bar, at least one first cable attached to the first safety bar, and an oxygen delivery system. The first cable supports the first safety bar at a predetermined depth. The oxygen delivery system consists of an oxygen tank, an oxygen delivery line, a manifold attached to the oxygen delivery line, and a plurality of regulators attached to the manifold. When the oxygen delivery system will be used by only one scuba diver, the oxygen delivery line can be connected directly to a single regulator without the manifold. The first cable and oxygen tank are attached to a float, which is either secured to a boat or platform via a tether line or anchored to the sea floor. In an alternative embodiment, the first cable is attached directly to a boat or platform, and an oxygen supply is provided on the boat or platform.

Abstract: A diaphragm holder for pressure regulator of air tank used in diving includes a diaphragm seat formed on the pressure regulator for holding a rubber diaphragm therein, a cover for closing onto a top of the diaphragm seat, and a soft push member integrally formed on the cover. The diaphragm seat is provided on an outer wall surface with spaced raised rails, and the cover is provided on an inner wall surface with L-shaped grooves corresponding to the raised rails on the diaphragm seat. Each of the L-shaped grooves includes communicable wide and narrow groove portions. By closing the cover to the diaphragm seat with the wide groove portions aligned with the raised rails and turning the cover, the rails are moved into the narrow groove portions to lock the cover to the diaphragm seat with the soft push member correctly located at an outer side of the rubber diaphragm.

Abstract: A pressure regulator suitable for use as a breathing demand valve in self-contained breathing equipment comprising a first chamber incorporating an inlet port having an inlet valve therein, preferably in the form of a poppet valve and biased so as to seal of the inlet port, and separated from a second chamber by a diaphragm. The diaphragm co-operates with the end of a stem extending from the poppet valve member of the inlet valve such that, upon inhalation by the user, the diaphragm is deflected towards the inlet valve and exerts a force on the poppet valve stem sufficient to open the poppet valve and, upon exhalation by the user, the diaphragm is deflected away form the inlet valve so that the diaphragm no longer contacts the end of the poppet valve stem and the inlet valve closes.

Abstract: This invention relates to a feeding apparatus for breathing masks that allows food and drink intake when the mask is in use, does not reduce the wearer's field of vision, requires little space, and is protected from dirt or other contamination. It is the problem of this invention to provide a feeding apparatus for breathing masks that does not reduce the wearer's field of vision, is protected from dirt or other contamination and allows for contamination-free insertion of a drinking cannula, if required. The problem of the invention is solved by placing a pivoting check valve (1) that can be closed using a sealing cap (5) and tightly encompasses a hollow axle (2) in a fitting 4 on the outside of the breathing mask. The hollow shaft (2) of the feeding apparatus is equipped with a hose and mouthpiece (3) on its end inside the breathing mask.

Abstract: A Self Contained Re-breathing apparatus with a single bank of oxygen sensors for signaling oxygen contact back to a display and oxygen valve control, where the signal is set via two identical and independent sets of signal control circuitry which are interconnected in a primary and secondary relationship. The primary circuitry controlling the valve and the secondary circuitry sending a signal to a display, wherein the two identical and independent sets of circuitry can perform each role and serve to confirm the satisfactory operation of a master signal processing circuit.

Abstract: A swim and skin-dive snorkel is presented which uniquely provides positive end-expiratory pressure for pressure-balanced exhalation. The inventions include both devices and methods for providing positive end-expiratory pressure to the respiratory passages of a user of underwater breathing equipment. The inventive snorkel includes inhalation and exhalation conduits. Air can be exhaled by a user into a chamber from which exhaled air is released when exhalation pressure within the chamber exceeds a threshold pressure. In this manner the device provides positive end-expiratory pressure during exhalation. In an embodiment of the invention, upon receiving adequate exhalation pressure from the swimmer's airways, a sealing member is outwardly displaced against the ambient water pressure, thereby opening the exhalation conduit to receive exhaled air. The pressure maintained within the snorkel is adequate to keep the inhalation valve closed, except when the swimmer is actively inhaling.

Abstract: A breathing apparatus for a diver is configured to include a second stage pressure regulator and a hollow exhaust tube. An input port is located on a side of the pressure regulator and is attached to a supply hose coming from a tank mounted on a scuba diver's back. Additionally, an exhaust port is located on the same side of the regulator as the input port. The hollow exhaust tube is attached to the exhaust port. The exhaust tube is able to trap gas therein by the placement of one-way valves at each end of the exhaust tube, thus supplying a counteracting buoyant force to the same side of the regulator as the side where the supply hose enters the regulator, while defining an exhaust port arranged so that bubbles leaving the exhaust tube do not obstruct the diver's vision. The regulator may be fit with a supporting surface designed to rest on a diver's chin.

Abstract: A portable life support system includes a primary oxygen supply in thermal communication with a recirculated ventilation flow from a user. The primary oxygen supply has a solid adsorbent bed made of a molecular sieve that adsorbs oxygen at cryogenic temperatures and desorbs oxygen when heated. The primary oxygen supply freezes carbon dioxide and moisture in the recirculated ventilation flow. A wire mesh is adjacent to the primary oxygen supply to contain frozen carbon dioxide and moisture. A first ice chest is downstream of the primary oxygen supply to condition the temperature and humidity of the recirculated ventilation flow. A liquid cooled garment associated with the suit is in thermal communication with the first ice chest.