EP0025444A1

EP0025444A1 - Processes and devices for regulating the partial pressure of oxygen of the gas mixture in a respiratory circuit of a diver.

Info

Publication number: EP0025444A1
Application number: EP80900493A
Authority: EP
Inventors: Masson Yves Le
Original assignee: LABORATOIRES DE MECANIQUES APPLIQUEES "LAMA"; LAMA LAB MEC APPLIQUEES
Current assignee: LABORATOIRES DE MECANIQUES APPLIQUEES "LAMA"; LAMA LAB MEC APPLIQUEES
Priority date: 1979-03-21
Filing date: 1980-10-08
Publication date: 1981-03-25
Also published as: IT1130983B; WO1980002016A1; IT8020735A0; EP0025444B1; US4362154A; DE3064470D1

Abstract

Regulation de la pression partielle d'oxygene dans le circuit respiratoire en circuit ferme d'un plongeur. On preleve en continu un echantillon du melange gazeux du circuit; on l'envoie dans la chambre de veile (2) ou l'on mesure sa pression partielle d'oxygene et ou l'on produit un signal electrique de commande si la pression mesuree devient inferieure a une valeur de consigne, et on utilise ce signal pour declencher une injection au plongeur (4) d'une quantite definie d'un melange gazeux riche en oxygene. Application aux plongees en eau profonde.Regulation of the partial oxygen pressure in the closed circuit respiratory circuit of a diver. A sample of the gas mixture in the circuit is continuously taken; it is sent to the monitoring chamber (2) where its partial oxygen pressure is measured and where an electrical control signal is produced if the pressure measured becomes lower than a set value, and we use this signal to trigger an injection to the diver (4) of a defined amount of an oxygen-rich gas mixture. Application to diving in deep water.

Description

Methods and devices for regulating the partial pressure of oxygen in the gas mixture of the respiratory system of a diver

The invention relates to regulating the partial pressure of oxygen in the gas mixture of the respiratory circuit of a diver, said plunger being equipped with a breathing apparatus operating in closed circuit and being connected to a standby chamber located at a distance and where a pressure equal to or close to atmospheric pressure prevails.

It applies in particular to the case of divers connected to a submarine of the "spit-diver" type and operating at a depth of up to 300 meters.

The intervention at great depths of divers from submarines requires the use of respiratory systems with low consumption, the quantity of gas storable on board submersibles being limited.

Respiratory systems of this type are "closed circuits" where the partial pressure of oxygen is measured in order to control the admission of oxygen. The devices known to date are from compact type. As a result, the pressure and humidity conditions impose on the electronic measurement device, a complexity and a quality of the components such as these systems are expensive and require special supervision and skill of the diver. Now, it is certain that the primary function of the diver is to do an efficient job. It is penalizing to impose a respiratory concern on him when he is in a situation of pressure which affects his reflexes, his spirit of decision and initiative.

The present invention aims to free the diver from all respiratory concerns by entrusting this monitoring to personnel who are nearby in the atmospheric observation chamber of the submarine.

According to the invention, this is achieved by a process in which:

(a) a continuous sample of the gas mixture is taken from the diver's breathing circuit,

(b) this sample is sent to the standby chamber, the partial oxygen pressure of the sample is measured there and an electrical control signal is produced there if the measured pressure falls below a set value, and

(c) the command signal is used to initiate an injection of a defined quantity of a gas mixture rich in oxygen into the respiratory circuit of the diver. By transferring the entire measurement and regulation device to the atmospheric chamber, not only does the electronics work under standard conditions of pressure and humidity, but the respiratory system worn by the diver is reduced to a simple and space-saving device . In a typical example, the sample consists of a flow rate in the range 0.2 to 0.6 normal liters per minute.

In a preferred embodiment, the sample from the respiratory circuit is sent to the standby chamber by a capillary conduit so that the variation in the partial pressure of oxygen at the outlet of the capillary reproduces the variation in this pressure at the inlet of the capillary, therefore in the respiratory circuit, with a delay, the section of the capillary being chosen to limit the duration of the transfer of the sample along the capillary.

In a preferred embodiment, the interval between two injections is used to prepare said defined quantity.

In a preferred embodiment, said defined quantity is prepared by loading a capacity with the oxygen-rich mixture under a determined differential pressure. In a preferred embodiment, said injection is carried out by discharging, in a simple conduit terminating in the respiratory circuit, a capacity previously filled with the mixture rich in oxygen under a determined differential pressure. The invention is not limited to this application.

Thus, the respiratory system which equips the diver to provide him with the gaseous mixture which he must breathe, instead of being carried by the diver, can be a chamber or a chamber in which the diver is located and in which reigns an atmosphere that is breathed by the diver.

According to one application, the respiratory system is a chamber in which the diver is located and which contains a gas mixture breathed by the diver.

In one case, this room is a hyperbar room placed in a room constituting the standby room and intended to simulate the diving depth.

In another case, the chamber is a working box submerged at the working depth.

In another application, the plunger moves in the water from a submerged chamber constituting a plunger chamber connected to a watch chamber located on board a surface vessel, and the gas mixture is prepared in this submerged room. These various applications will be described below, with reference to the figures in the attached drawing in which:

. Figure 1 is a general diagram of the device; . Figure 2 is a diagram of the diver's breathing circuit;

. Figure 3 is a diagram of part of the device;

. Figure 4 is a diagram of a device according to the invention in the case of a hyperbar chamber;

. Figure 5 is a variant of the device of Figure 4;

. Figure 6 is a diagram of a device according to the invention in the case of a working box;

. Figure 7 is a variant of the device of Figure 6; and

. Figure 8 is a diagram of a device according to the invention in the case of a turret diving.

Figure 1 shows a "spit-diver" submarine 1 which includes a watch chamber 2 where atmospheric pressure prevails and where the surveillance personnel are held and a compartment 3 at bottom pressure where the divers stand. It is assumed that a diver 4 has left this compartment and is moving in deep water, say at 100-300 meters. The plunger 4 is equipped with a breathing device (Figures 1 and 2) which constitutes a closed breathing circuit comprising a mouthpiece or mask 5 connected by two tubes 6, 7 to a flexible bag 8 of four to five liters. Check valves 9 ensure the circulation of gases in the direction indicated by the arrows, in a manner known per se. The circuit includes a cartridge 10 for fixing the exhaled carbon dioxide and a valve 11 for discharging an overflow of gas, if necessary.

According to the invention, this circuit (for example in the region of the bag 8) is connected to the submarine by an umbilical 12 which contains two conduits 13, 14 communicating with the interior of the circuit.

The conduit 13 is a capillary conduit of very small section (of the order of 0.5 mm in diameter) which connects the circuit to a measuring device 15 located in the standby chamber 2 of the submarine. The apparatus 15 continuously measures the partial pressure of oxygen of the gas sampled by the capillary 13 and supplies, as a function of this measurement, an electrical signal which controls by a Season 16 a three-way electro-pneumatic distributor 17 located in the diving room.

The electro-pneumatic distributor 17 (Figures 1 and 3) has an outlet 17a to which the other conduit 14 of the umbilical leads, has a inlet 17b connected to an external reservoir 18 of breathable gas, via a pressure reducer 19 and, another inlet 17c connected to a capacity 20 of volume C located for example in the diving compartment 3. The distributor 17 puts the capacity 20 in relation either with the regulator 19 or with the conduit 14.

At rest of the distributor, the capacity 20 is in relation to the pressure reducer and is timed at a stabilized differential pressure Δp. During operation of the dispenser, it is connected with the conduit 14 in which it discharges by supplying the plunger with a quantity CΔp of breathable gas. The value of Δ p is preset and defined according to the oxygen content of the gas mixture used. Thus, at each discharge, the quantity of oxygen supplied to the diver is perfectly defined. Between two injections, the plunger breathing circuit is closed.

The measuring device 15 is adjusted to provide an electrical signal which controls the distributor in order to discharge the capacity 20 in the conduit 14 as soon as the detected partial pressure of oxygen is lower than a minimum set value. For example, according to the invention, the conditions are set so that each discharge the partial pressure of oxygen of the gas mixture breathed by the plunger is raised by a constant value of 200 mb. Between two injections, the plunger circuit is closed and this pressure changes between the minimum setpoint value (for example 300 mb) and this value increased by 200 mb (i.e. 500 mb). The frequency of injections depends on the work provided. At rest, it is about one injection every 2.5 minutes. In order to eliminate any risk of hyperoxia, .e oxygen content of the injected rich mixture is chosen so that at the working depth, its partial oxygen pressure is close to 1000 mb. If necessary, the diver can then use this mixture freely thanks to a direct supply link 21 which connects the respiratory circuit of the plunger to the regulator 19 under the control of a manual control 22. In particular, this manually controlled supply allows to adjust, if necessary, the respiratory tidal volume.

The "oxygen rich" gas mixture is a mixture which is richer than the set value. Ultimately, this mixture can be pure oxygen. The device is best suited for diving depths of 20 to 300 meters, with the capillary providing insufficient flow at less than 20 meters and excessive response time at more than 300 meters. In the embodiments of Figures 4 to 7, the device comprises:

. a room D where the diver is located;

. a capillary gas conduit 13 between this chamber and an apparatus for measuring the partial pressure of oxygen 15 located in a monitoring chamber where a pressure close to atmospheric pressure prevails, this apparatus being capable of measuring the partial pressure of oxygen of the gas mixture of said chamber where the plunger is located and providing a control signal when this pressure becomes less than a set value;

. a gas supply pipe 14 opening into the chamber where the plunger is located; and · means G for preparing a quantity defined by an oxygen-rich gas and injecting said quantity into said supply conduit under the control of said control signal.

The means G represent all of the means 17 (distributor), 19 (regulator), and 20 (capacity) of the device of FIG. 1 or equivalent means.

In the embodiment of FIG. 2, the chamber D is a hyperbar chamber and the means G are located outside the chamber, this exterior constituting the standby chamber.

Preferably, the regulator 19 is piloted by the pressure inside the chamber D, this piloting link being represented by the link in dotted lines in the drawing.

In the embodiment of Figure 5, the means G are placed inside the hyperbar chamber D (decompression chamber or saturation chamber). In the embodiment of Figures 6 and 7, the chamber D constitutes a work box directly placed on the work site and the diver works there dry, without a respiratory mask so that it directly breathes the atmosphere of the room. In the embodiment of FIG. 6, the pneumatic system is located in a standby chamber forming part of a surface vessel N. This chamber is connected to the working chamber by the capillary conduit 13 leading to the measuring device 15 and by the supply duct 14 connecting the interior of the working box to the pneumatic system G.

In the embodiment of Figure 7, the pneumatic system G is placed in the box itself and the standby chamber contains only the measuring device 15.

In the embodiment of Figure 8, the device comprises:

. a closed circuit respiratory device 8 carried by the diver;

. a watch chamber located on board a surface ship N and in which there is a pressure close to atmospheric pressure;

. a capillary gas conduit 13 between said circuit and a device for measuring the partial pressure of oxygen 15 located in the standby chamber, this device being able to measure the partial pressure of oxygen of the gaseous mixture of said circuit and to provide a control signal when this pressure falls below a set value;

. a submerged plunger chamber P provided with means G for preparing a defined quantity of an oxygen-rich gas and for injecting said quantity into a gas supply duct 12 connecting the plunger chamber to the respiratory circuit of the plunger, under the control of said control signal.

Claims

1. Method for regulating the partial pressure of oxygen in the gas mixture of the respiratory circuit of a diver, the diver being equipped with a breathing apparatus operating in closed circuit and being connected to a standby chamber situated at a distance and where there is a pressure equal to or close to atmospheric pressure, characterized in that:

(a) a continuous sample of the gas mixture is taken from the diver's breathing circuit; (h) this sample is sent to the standby chamber, the partial oxygen pressure of the sample is measured there and an electrical control signal is produced there if the pressure measured becomes lower than a set value; and (c) using the control signal to initiate an injection of a defined amount of an oxygen-rich gas mixture into the breathing circuit of the diver.

2. Method according to claim 1, characterized in that the sample is sent from the respiratory circuit to the waking chamber by a capillary conduit so that the variation in the partial pressure of oxygen at the outlet of the capillary reproduces the variation of this pressure at the inlet of the capillary, therefore in the respiratory circuit, with a delay, the section of the capillary being chosen to limit the duration of the transfer of the sample along the capillary.

3. Method according to one of claims 1 or 2, characterized in that the interval between two injections is used to prepare said defined quantity.

4. Method according to one of claims 1 to 3, characterized in that said defined quantity is prepared by loading a capacity with the mixture rich in oxygen under a determined differential pressure.

5. Method according to one of claims

1 to 4, characterized in that said injection is carried out by discharging, in a simple conduit terminating in the respiratory circuit, a capacity previously filled with the mixture rich in oxygen under a determined differential pressure.

6. Method according to one of claims 1 to 5, characterized in that the breathing circuit is maintained. plunger closed between two injections.

7. Method according to claim 1, characterized in that the respiratory apparatus of the plunger comprises a chamber where the plunger is located and which contains a gas mixture breathed by the plunger.

8. Method according to claim 7, characterized in that said chamber is a hyperbar chamber placed in a room constituting the standby chamber and intended to simulate the diving depth.

9. Method according to claim 7, characterized in that said injection is carried out by discharging, in a simple conduit terminating in the hyperbar chamber, a capacity previously filled with the mixture rich in oxygen under a determined differential pressure.

10. The method of claim 9, characterized in that said capacity is filled from a source of said oxygen-rich gas mixture via a pressure regulator controlled by the pressure in the hyperbar chamber.

11. Method according to claim 7, characterized in that said chamber is a working box immersed in the working depth.

12. Method according to claim 1, characterized in that the said gaseous mixture is prepared in an immersed chamber constituting a plunger chamber connected to a watch chamber located on board a surface vessel.

13. Device for applying a method according to one of claims 1 to 6 in the case of a diver connected to a submarine comprising a watch chamber where a pressure close to atmospheric pressure prevails, characterized in that that it includes:

. a closed circuit breathing device worn by the diver;

. a capillary gas conduit between this circuit and a device for measuring the partial pressure of oxygen located in the waking chamber, this device being capable of measuring the partial pressure of oxygen of the gaseous mixture of the respiratory circuit and of supplying a signal control when this pressure falls below a set value;

. means on board the submarine for preparing a defined quantity of an oxygen-rich gas; . a gas supply pipe connecting the breathing circuit of the diver to the submarine; and

. means associated with the measuring apparatus for injecting said quantity into said supply conduit under the control of said control signal.

14. Device according to claim 13, characterized in that it comprises on board the submarine a pneumatic device connected to a reserve of breathable gas rich in oxygen, to a capacity and to said supply conduit, this pneumatic device being controlled by the measuring device to establish communication, either between the reserve and the capacity for loading the latter, or between the capacity and said conduit for discharging the capacity in the conduit.

15. Device according to one of claims 13 or 14, characterized in that the pneumatic device is located in a compartment of the submarine which constitutes a plunger chamber.

16. Device for implementing a method according to claim 7, characterized in that it comprises:

. a room where the diver is located; . a capillary gas conduit between this chamber and an apparatus for measuring the partial pressure of oxygen located in a standby chamber where there is a pressure close to atmospheric pressure, this apparatus being capable of measuring the partial pressure of oxygen in the mixture gaseous from said chamber where the plunger is located and to supply a control signal when this pressure becomes lower than a set value;

. a gas supply conduit opening into the chamber where the plunger is located; and

. means for preparing a defined quantity of an oxygen-rich gas and injecting said quantity into said supply duct under the control of said control signal.

17. Device according to claim 16, for the implementation of a method according to one of claims 2 to 4, characterized in that said chamber where the plunger is located is a hyperbar chamber.

18. Device according to claim 16, for implementing a method according to claim 5, characterized in that said chamber where the plunger is located, is a working box immersed at the working depth.

19. Device for implementing a method according to claim 12, characterized in that it comprises:

. a closed circuit breathing device worn by the diver; . a watch chamber located on board a surface ship and in which there is a pressure close to atmospheric pressure;

. a capillary gas conduit between said circuit and an apparatus for measuring the partial pressure of oxygen located in the standby chamber, this apparatus being capable of measuring the partial pressure of oxygen of the gaseous mixture of said circuit and of providing a signal control when this pressure falls below a set value; . an immersed plunger chamber provided with means for preparing a defined quantity of an oxygen-rich gas and for injecting said quantity into a gas supply duct connecting the plunger chamber to the respiratory circuit of the plunger under the control of said control signal .