Abstract:
A diving system that includes a flexible breathing gas reservoir designed to float at sea surface and including a power supply circuit through which a diver is connected to the flexible reservoir to obtain breathing gas. The system includes a device for interrupting the power supply circuit which interrupts the breathing gas supply of the diver when the pressure in the reservoir is lower than a predetermined threshold.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to underwater diving systems comprising a breathing gas reservoir that remains at the water surface.  
           [0003]    2. Description of Background and Relevant Information  
           [0004]    In systems of the above-mentioned type, commonly referred to as “hookah diving systems,” the diver is connected to the reservoir by a supply circuit having a hose that is generally relatively long to enable the diver to move in a certain zone around and beneath the reservoir. Unlike the diving systems in which the diver takes the air reservoir with him under water, the diver who uses a hookah system only takes under water the hose whose free end is provided with a mouthpiece or a facial mask.  
           [0005]    There are various types of reservoirs for the hookah systems. Some of them are rigid, others are flexible. Among the advantages of the flexible reservoirs is the fact that the reservoir is lightweight and can be made very compact when the system is not in use. This makes it easier in particular to transport the system to the practice site.  
           [0006]    The principle of a hookah system having a flexible reservoir is described, for example, in the document GB-2,164,259. This document provides that an operator, who remains at the surface, must make sure that the reservoir is kept full of air at all times. Therefore, this implies that the reservoir is constantly connected to a (manual or non-manual) pump, and that this pump is constantly actuatable. Therefore, one can conclude that this diving system is adapted to be used from a boat or from a platform floating at the water surface.  
           [0007]    A similar system is described in the document EP-A-437 948. This document specifies that the flexible reservoir is preferably encircled by a ring of buoyant material.  
           [0008]    In any case, it is indeed desired that the reservoir continue floating at the surface, even at the end of the dive, not only to prevent the diving system from sinking, but particularly to form a buoy on which the diver can take support at the end of the dive. However, since the reservoir is flexible, its volume is going to decrease, particularly at the end of the dive, if the diver breathes all of the gas contained in the reservoir.  
           [0009]    The solution of the document GB-2,164,259 consisting of providing a second operator on a platform at the surface is not satisfactory, insofar as this limits the autonomy of the diver who cannot dive where he wants and who is forced to be accompanied by a person who cannot dive. The solution of the document EP-1-437 948 is not satisfactory either insofar as the ring of buoyant material can prove cumbersome when one wishes to store the diving system after returning to shore.  
         SUMMARY OF THE INVENTION  
         [0010]    The object of the invention is to propose a diving system whose design is simple and practical, and which makes it possible to guarantee, by means of a compact device, that the reservoir continues floating at the water surface, even at the end of the dive.  
           [0011]    To this end, the invention proposes a diving system comprising a flexible breathing gas reservoir adapted to float at the water surface and comprising a supply circuit through which a diver is connected to the flexible reservoir in order to draw breathing gas therefrom, wherein the system comprises a device for shutting off the supply circuit which interrupts the breathing gas supply to the diver when the pressure inside the reservoir drops below a predetermined shut-off threshold. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    Other characteristics and advantages of the invention will become apparent upon reading the description that follows, with reference to the annexed drawings, in which:  
         [0013]    [0013]FIG. 1 schematically shows a diving system according to the teachings of the invention;  
         [0014]    [0014]FIG. 2 schematically shows an example of embodiment of a supply shut-off device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    [0015]FIG. 1 shows a diving system  10  comprising a breathing gas reservoir  12  under pressure, and comprising a supply circuit  14  which enables the diver underwater to breathe the gas contained in the reservoir  12 . According to the invention, the reservoir is a flexible reservoir, and it is adapted to remain at the water surface. The supply circuit  14  is very schematically represented by a supply hose  16  that is connected to the reservoir, and the free end of which is provided with a mouthpiece  18  preferably incorporating a reducing valve through which the diver can draw the breathing gas contained in the reservoir  12 . The diving system  10  also comprises means (not shown) that allow filling the reservoir with a breathing gaseous mixture such as air. These means can be a single device for connecting to an air compressor. They can also be means adapted to be carried with the reservoir. For example, air is stored in the reservoir  12  under a maximum pressure of 10-20 bars. In certain cases, a two-stage pressure reducing valve system can be provided, particularly if the air storage pressure is high.  
         [0016]    The reservoir  12  is a flexible reservoir in the sense that at least some of the walls that demarcate it are capable of becoming deformed, making it possible to decrease or increase both the internal and external volumes of the reservoir. Preferably, however, the reservoir has an inextensible maximal volume, which is reached, for example, upon an absolute pressure on the order of 1.2-1.5 bars. From this pressure, the reservoir will have reached an “inflated” state and, beyond, its volume will no longer increase significantly. Conversely, the reservoir will preferably have a very small external volume once it is “deflated.” 
         [0017]    In the example shown, the reservoir is a fully flexible reservoir constituted of a bag made of a waterproof fabric. This construction is both simple and lightweight, and it allows making the reservoir extremely compact when not in use. Indeed, the reservoir  12  can be completely deflated and folded. The constituent material can also be a flexible and impervious plastic material (for example, polyurethane), or the reservoir can be constructed with a multilayered material including a first layer of material ensuring the mechanical resistance to pressure and at least one impervious inner layer.  
         [0018]    Alternatively, the reservoir can be only partially flexible. Thus, it could comprise at least one rigid or semi-rigid surface making it possible to attach accessories such as carrying straps or systems for connecting to a reservoir filling device, and even to attach the means for connecting the supply circuit  16 . The reservoir could also have two opposing rigid walls joined to one another by flexible walls, such that the reservoir is substantially parallelepipedic in the position of use, but that it is in the form of a thin, rigid flat rectangle in the position of storage. The flexible walls could also be constituted of rigid elements articulated between each other.  
         [0019]    Similarly, in the example shown, the reservoir  12  forms the entire emerged portion of the diving system. But the system could be provided to comprise other components or accessories. By way of example, the diving system can be provided to comprise a device for filling the reservoir, for example, a motorized pump, or a human-actuated pump, such as a manual pump. This pump could also be integrated in a compartment affixed to the reservoir. In this case, the reservoir can play the role of a float by providing these accessories with a buoyancy reserve in order to maintain the assembly at the water surface, without it being necessary to provide a special flotation device. According to another example, the reservoir can be associated with a rigid or semi-rigid structure forming, in combination with the reservoir, a hydrodynamic float on which the diver can take support in order to swim at the water surface with a minimum of effort. Still further, the diving system can be provided to comprise, in addition to the flexible reservoir according to the invention, at least one auxiliary reservoir that can be rigid or flexible.  
         [0020]    In any case, one understands the advantage for the float to maintain its full floating ability, or at least a significant portion thereof.  
         [0021]    Thus, according to the invention, the diving system  10  comprises a device  20  for shutting off the supply circuit  14  which, below a predetermined pressure threshold in the reservoir  12 , prevents the diver from drawing air from the reservoir. The predetermined pressure threshold is determined as a function of the pressure necessary for maintaining the reservoir  12  in an “inflated” state in which it conserves its full or at least a significant portion of its floating ability.  
         [0022]    This predetermined shut-off threshold can be, for example, an absolute pressure threshold in the reservoir. It can thus be set to an absolute pressure value comprised between 1.2 and 1.5 bars. It can also be a relative pressure threshold in the reservoir in relation to the atmospheric pressure, the shut-off device imposing in the reservoir a pressure which is greater than the atmospheric pressure, for example, 50-200 millibars.  
         [0023]    [0023]FIG. 2 shows an example of a shut-off device that is capable of being used for implementing the invention. The shut-off device  20  here is a calibrated valve made in the form of a membrane differential pressure valve, which member is known per se, and it is shown in the position for shutting off the supply.  
         [0024]    The valve thus comprises a box  22  that imperviously divided into two chambers by a membrane  24 : a circulation chamber  26  and a control chamber  28 . The control chamber  28  is open to the atmosphere, such that the pressure prevailing therein is the atmospheric pressure. The circulation chamber  26  is in turn divided into two compartments: an upstream compartment  30  that is connected to the interior of the reservoir  12 , and a downstream compartment  32  to which the supply hose  16  is connected. The two compartments  30 ,  32  communicate at the level of a circular seat  34  arranged opposite the membrane  24 . The membrane  24  carries a flat shutter  36  that is capable of pressing itself against the seat  34  in order to interrupt any fluid circulation between the two compartments  30 ,  32 . Finally, a compression spring  38  is arranged in the control chamber  28  to prestress the shutter  36  toward the seat  34 .  
         [0025]    When, on each side of the shutter  36 , the force of the air pressure in the reservoir  12  is greater than the sum of the force of the atmospheric pressure and of the prestress of the spring  38 , the shutter  36  is separated from the seat  34 , and air can circulate from the reservoir  12  toward the supply hose  16 , therefore toward the diver. Conversely, as soon as the force of the air pressure in the reservoir  12  drops below said sum, the shutter  36  is pressed against the seat  34  by the spring  38 , which interrupts air circulation as shown in FIG. 2. The diver can no longer continue to empty the reservoir; therefore, air pressure within the reservoir cannot drop below a threshold value, such that the reservoir cannot deflate, and it maintains its floating ability.  
         [0026]    Naturally, the embodiment of the shut-off device that is proposed here is only a non-limiting example. Other known shut-off devices fulfilling the same function can be used for implementing the invention.