US3770938A

US3770938A - Tank heater for respiratory mixtures used in deep diving

Info

Publication number: US3770938A
Application number: US00176894A
Authority: US
Inventors: C Agarate
Original assignee: PETROLES FR CIE DES
Current assignee: DES PETROLES FR CIE FR; PETROLES FR CIE DES
Priority date: 1971-02-12
Filing date: 1971-09-01
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06
Also published as: GB1351101A; FR2126592A5; IT953405B

Abstract

A tank heater for respiratory mixtures used in deep underwater diving which includes a heating coil of a plurality of counter wound wires enclosed within a sealed gas tank for heating and closely regulating the temperature of the breathing gas fed to an underwater diver. A temperature sensor is located within the tank adjacent the outlet port of the tank and is connected to appropriate electrical control circuits and a suitable power supply to control the heating coil. The tank and wires are insulated. The tank can also serve as a reserve tank of gas for the diver.

Description

T 1 "I1 I}, A

ate ates tent 1191 [111 3,770,% Agarate 1 Nov, 6, 1973 1 TANK HEATER F9113 RESEHRATORY 3,445,677 5/1969 Leftwich 219/501 UX MIX R g USED 1 BEEP [pH/ENG 3,107,669 10/1963 Gross 128/212 X 2,199,724 5/1940 Herbert. 128/145 R 1 Inventor: Qhristian g e, o ex, 3,239,650 3/1966 Parks 219/374 France A 7 2,515,835 7/1950 Preston 137/341 8 [73] Ass1gnee: Compagnie Francaise Des 3'344257 9/1967 Moeuer 219,3 1 x Pctroles, Paris, Compagnie FOREIGN PATENTS OR APPLICATIONS Maritime DExpertises, Marseille, 1,182,300 2 1970 Great Britain 219 375 both of France [22] Filed: Sept. 1, 1971 Primary Examiner-A. Bartis App]. No.: 176,894

[30] Foreign Application Priority Data Feb. 12, 1971 France 7104747 [52] 11.8. C1 219/3741, 128/142.4, 128/212, 137/341, 219/307, 219/331, 219/364, 219/381 [51] int. Cl. 11051 11/00, F24h 3 /04, A62b 7/02 [58] Field 011 Search 219/363, 359, 364, 219/366, 370-376, 379-381, 501, 306, 307, 328-331; 137/341; 128/212, 142.4, 142.2, 142, 145 R [56] References (Iited UNITED STATES PATENTS 3,582,613 6/1971 Pies 219/381 2,677,750 5/1954 Taylor 219/382 1,527,292 2/1925 Barlow 219/366 2,458,225 H1942 Trilling et a1... 338/63 3,560,710 2/1971 Fuellemann 219/379 X Attorney-Richard C. Sughrue et a1.

[5 7] ABSTRACT A tank heater for respiratory mixtures used in deep un- 8 Claims, 5 Drawing Figures United States Patent 1 Agarate Nov. 6, 1973 pE/N TED afar/ m TANK HEATER FOR RESPIRATORY MIXTURES USED IN DEEP DIVING BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater for use in a respiratory system for underwater divers who are forced to operate at great depths and at low temperature. In particular, the present invention is directed to providing a device to maintain the temperature of the breathing mixture that the diver utilizes in this respiratory system, and thereby prevent any caloric hemorrhage.

2. Description of the Prior Art It is known that divers working at great depths under low temperature and high pressure, are subject to the dangers of caloric hemorrhage due to the pressure and the cold of the breathing mixture that they are forced to utilize in their respiratory system. Thus, it becomes indispensable to heat the respiratory mixture in order to assure that the divers will survive.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a respiratory mixture heating apparatus, that utilizes an air-tight tank equipped with two openings, one for the entry of the gaseous mixture and the other for its exit. The air-tight tank incorporates an electrical resistance device to heat the respiratory mixture by using either a direct or an alternating current supply device, in cooperation with a device for controlling the flow of current as a function of the desired temperature. In particular, the electrical resistance utilized in the heater, is never brought to a temperature higher than T+ A T, where T is the desired temperature of the respiratory mixture at the entrance to the breathing ducts and A T is the temperature rise created by the resistance heater with respect to the temperature T, taking into account calory loss undergone by the gas at the opening of the air-tight tank with the breathing mask of the diver. The quantity of temperature represented by A T, is made as small as possible by the choice ofa large capacity calorific resistance filling the principal portion or capacity of the tank where the gas mixture circulates.

A principal advantage of the present invention is that it provides a device in which none of the parts will be at a temperature that would create the risk of burning the diver, even if he, by virtue of a relatively long apnoea, causes an increase in the contact time between the resistance heater and the respiratory breathing mixture.

An object of the present invention is to provide a heater device in which the resistance is made up of a conducting wire that is provided with a fine insulating layer which can be folded back upon itself and which can be arranged inside a tank or container that is capable of having a volume on the order of magnitude of the respiratory capacity of the diver.

By the present invention, we not only provide an extremely simple and economical device, but also a heating device where the temperature can be regulated in an easy fashion, and with great precision, and which does not require a large inductance coil to be introduced into the system with its resultant hazards to the diver.

Another object of the present invention is to provide a resistance heater where the respiratory mixture introduced into the tank is at a pressure higher than the utilization pressure employed by the diver and where the resistance is formed by several conducting wires with low specific resistance, these wires being laid out in parallel fashion.

The present invention permits the temperature regulation to be improved by increasing the volume of gas in contact with the resistance heater and by increasing the output of the apparatus, by increasing the contact surface between the gas under pressure and the parallel low specific resistance conducting wires that make up the resistance heater. If the tank is a module separate from the main container of the respiratory mixture, it can also be utilized as a gas reserve which will momentarily provide the diver with a safety factor with which he could attempt to reach his submarine station, if for example, he is linked by a flexible gas supply. The capacity of the tank is capable of maintaining the value of A T very low in spite of the slight temperature drop brought about by the pressure regulator which is necessary to supply the diver with a gas at his required pressure.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and aspects of the present invention will emerge more fully from the following specifications given here with reference to the attached drawings in which:

FIG. 1 is a cross-sectional view of the tank and resistance heater;

FIG. 2 is a schematic view of the electrical control circuits of the present invention;

FIG. 3 is a schematic view of a modification of the electrical control circuits of the present invention; and

FIG. 4 is a schematic view of another modification of the electrical control circuits of the present invention.

FIG. 5 is a schematic drawing of a conducting wire which may be used with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 discloses a tank in the form of a metallic cylinder, designed to resist both external and internal pressure. The outside wall 24 of the tank 10, for example, resists an internal pressure of 15 bars. A clamp 25 having a bottom plate 26, is held together by bolts 27 and sealed by joints 28, to make it possible to insure the closing and tightness of the tank. Other methods of closing the tank can be utilized such as, a circular lid, held in place by a circular clip. Although it is possible to make the device of the present invention serve several divers, the preferred manner of implementing thepresent invention is as an individual apparatus which can be easily attached to the diver by appropriate straps. One of the advantages of using an individual device, is that the pipelines conducting the gas from the apparatus outlet to the breathing mask of the diver is thereby reduced in length and in contact with the relatively cold environmental water. This, of course, makes it possible to lower the heat loss that would be undergone by the gas in the course of its travel through this conduit. Various means can be utilized in attaching the apparatus of the present invention to the diver, and since it does not form any part of the present invention, it is not shown in the present drawings. In addition, the

pipeline conducting the gases from the principal tank holding the breathing mixture, with for example, a high helium content, to the input connection 1 shown in FIG. 1, is shown schematically. Generally this pipeline connection will utilize a non-return valve for safety features and to permit the tank to be utilized as a secondary reserve of respiratory mixture. Since the outlet pipeline is also not a relevant feature of the present invention, it is also shown schematically as connected to connection 2, which is located opposite connection 1. Generally, the output pipeline would lead to the pressure regulator, required to supply the diver with gas and he, in the course of an inspiration, would cause the exit of a certain variable volume of gas which would leave the heater apparatus. The lead wires, which connect the resistance heater are schematically shown as connected to an electrical supply source 3.

The electronic control circuits can be included in a printed circuit block 4, while the assembly formed by the electric circuits can be positioned at 5. This assmebly is advantageously cooled by the gas volume that is entering through connection 1. The resistance heater is schematically represented by the grid shown at 6 in the drawings, simply to make the design appear clearer. This resistance actually consists of four

bundles

6A, 6B, 6C, and 6D each made up of a very long metallic wire with the low specific resistance, such as copper. In order to eliminate the thick inductance coil which would result from a simple winding, each of the four wires illustrated as 6A, 6B, 6C and 6D is folded back upon itself, before being inserted in bulk into the tank. Such a wire is illustrated in FIG. 5. These wires are covered with an insulating layer 30 that can be very thin, since the temperature will generally never exceed a maximum temperature on the order of 40C, and since the voltage used is relatively weak. The ends of each of' these wires have been designated as E and F to signify that they are connected respectively to the terminals E and F of the supply circuit shown in FIG. 2. The wires that form the heater(6a through 6d), are connected to these terminals, in parallel.

Referring to FIG. 2, a variable alternating voltage between 24 and 36 volts is applied to the

input terminal

7 and 8. A rectifier device 9 is capable of furnishing a continuous voltage difference between the

wires

12 and 13 with the help of a supplemental regulation device made up of the resistance and the break down diode 11. A bridge circuit which includes the regulating potentiometers l4 and 15 in one of its branches, contains a thermistor 16, which is, as shown in FIG. 1, placed opposite the output opening 2 of the tank. Thus, the thermistor represents the control temperature adjacent the output connection 2, which leads to a pipeline that connects with the divers mask. In case of any temperature variation, thermistor 16 will modify the conduction of transistor 17 and consequently, that of transistor l8. Coil 19 of transformer 20 will transmit an appropriate reaction in one direction or another to the coil 21, which is connected to the terminals 22A and 22B of the current controller 22. Current controller 22 is made up of a simple device, known under the name of Triac. Thus, the intensity of the current circulating in the wires that make up the resistance 6, is constantly controlled as a function of the temperature of the respiratory mixture available at the output of the tank. It is clear that the temperature control device can be replaced by other equivalent devices known in the art. By

10 30, makes it possible to furnish the voltage necessary for the thermo-contact 29 in case of any cut-off of the -Triafik... .7 t .7 7

Referring to FIG. 4, the thermo-contact 29 is mounted in series with the resistance 32 to control the power transistor 33. In this modification, the power supply source is continuous. The polarity of the continuous power supply is indicated on the schematic diagram. It should be noted that one or more thermostatic capsules could be placed in the feed circuit and could directly control the passage of the current into the heating element.

The bundles of wires 6a through 6d can be kept in place through means of, for example, a perforated plate 23 made of polyvinyl chloride, or any other rigid material which may be formed integrally with a sleevepositioned adjacent the interior surface of the walls 24 and outlet end of the tank 10. Since the apparatus is generally used at a great depth, it is designed to be thermally insulated from the ambient environment. For this purpose, the interior or the exterior of the apparatus is lined with the above-noted sleeve or layer of polyvinyl chloride, or any other material that would serve the function of insulating.

By virtue of the present invention, a relatively small volume tank is capable of heating a large volume of gas, since it provides a heating element with a relatively large surface. This volume'of the heating element constitutes an excellent means of thermal stabilization 40 which helps provide a regularity of operation by virtue of the very small temperature gradient which will be created between the heating resistance and the respiratory gas mixture. Since the respiratory gas mixture will generally contain a high proportion of helium, this gas will even further improve the homogenity of the temperature due to its high conductivity.

- s; wayarzraasrathe tank caaaw Be fliers at a pressure of 7 bars, which will provide, in the case of a breakdown in the main respiratory gas mixture supply, enough gas to the diver through his pressure regulator valve, to enable him to reach an emergency shelter. The heating resistance wires can be copper wire with a diameter of .9mm covered with a layer of enamel with a thickness of 0.022-0.04 mm. The length 5 of the wire can be several hundred meters and can occupy a large portion of the tank capacity in which the saz i t d m u simul t n Although the preferred embodiment has beeh de What is claimed is: 1. In a resipratory system for underwater divers having a breathing mixture supply and a breathing apparatus, the improvement comprising heating apparatus adapted to heat a breathing mixture as it flows from the 5 breathing mixture supply to the breathing apparatus, said heating apparatus comprising:

a tank housing having an inlet port and an outlet port;

a porous electrical heating means in said tank housing for heating the breathing mixture to a predetermined desired temperature, the heat-exchange surface area of said heating means being of such magnitude that, when said heating means is maintained at a temperature substantially equal to the predetermined desired temperature, a breathing mixture having an initial temperature below the desired temperature when introduced into said tank housing from the breathing mixture supply will have its temperature raised to be substantially equal to the predetermined desired temperature at said outlet port;

a source of electrical power connected to said heating means;

a sensor located within said tank housing adjacent to said outlet port, saidsensor being adapted to sense the temperature of its surroundings; and

electrical control means operatively connected to said source of electrical power, said sensor, and said heating means, said electrical control means being adapted to be responsive to said sensor to control the supply of electrical power to said heating means and to maintain the temperature of the breathing mixture at said outlet substantially equal to the predetermined desired temperature.

2. A heating apparatus as in claim 1, wherein the porous heating means includes at least two conducting wires electrically connected in parallel as the heater elements.

3. A heating apparatus as in claim 2, wherein each wire is folded back upon itself in said tank housing to prevent the formation of an inductance charge.

4. A heating apparatus as in claim 2, wherein each wire is insulated with an insulating layer of less than .1

5. A heating apparatus as in claim 1, wherein said tank housing is insulated against heat loss to the environment and has a wall thickness sufficient to withstand 15 bars pressure.

6. A heating apparatus as in claim 1, wherein said sensor is a thermistor and said electrical control means includes a current controller which is operatively connected to said thermistor.

7. A heating apparatus as in claim 1, wherein said sensor is a thermo-contact and said electrical control means includes a resistor in series with said thermocontact, a resistor in parallel with said thermo-contact, and a current controller which is operatively connected to said thermo-contact.

8. A heating apparatus as in claim 1, wherein said sensor is a thermo-contact, said source of electrical power in DC, and said electrical control means includes a resistor in series with said thermo-contact and a power transistor likewise in series with said thermocontact.

Claims

1. In a resipratory system for underwater divers having a breathing mixture supply and a breathing apparatus, the improvement comprising heating apparatus adapted to heat a breathing mixture as it flows from the breathing mixture supply to the breathing apparatus, said heating apparatus comprising: a tank housing having an inlet port and an outlet port; a porous electrical heating means in said tank housing for heating the breathing mixture to a predetermined desired temperature, the heat-exchange surface area of said heating means being of such magnitude that, when said heating means is maintained at a temperature substantially equal to the predetermined desired temperature, a breathing mixture having an initial temperature below the desired temperature when introduced into Said tank housing from the breathing mixture supply will have its temperature raised to be substantially equal to the predetermined desired temperature at said outlet port; a source of electrical power connected to said heating means; a sensor located within said tank housing adjacent to said outlet port, said sensor being adapted to sense the temperature of its surroundings; and electrical control means operatively connected to said source of electrical power, said sensor, and said heating means, said electrical control means being adapted to be responsive to said sensor to control the supply of electrical power to said heating means and to maintain the temperature of the breathing mixture at said outlet substantially equal to the predetermined desired temperature.

4. A heating apparatus as in claim 2, wherein each wire is insulated with an insulating layer of less than .1 mm.

7. A heating apparatus as in claim 1, wherein said sensor is a thermo-contact and said electrical control means includes a resistor in series with said thermo-contact, a resistor in parallel with said thermo-contact, and a current controller which is operatively connected to said thermo-contact.

8. A heating apparatus as in claim 1, wherein said sensor is a thermo-contact, said source of electrical power in D.C., and said electrical control means includes a resistor in series with said thermo-contact and a power transistor likewise in series with said thermo-contact.