Emergency flotation device using compressed gas

Abstract

A flotation device for providing emergency flotation for a person swimming or passing through a body of water, comprising a container filled with a charge of a gaseous material under a pressure such that it is in its liquid phase at normal environmental temperatures. The container is connected to a flexible flotation chamber through a passage which remains normally closed until actuated by the user. When the device is actuated by opening the passage, the charge expands into the flotation chamber, thereby inflating it, and providing support to the user in the water. The gaseous material has thermodynamic properties such that it remains in its liquid phase right up to the maximum temperatures to which the device is expected to be exposed to. Consequently, its volume, and hence the internal pressure within the gas container, does not increase significantly, thereby enabling the container to be of lightweight construction.

Claims

1. A flotation device comprising: a container adapted to hold a charge of a pressurized gaseous material having thermodynamic properties such that when compressed into the container at a pressure of not more than 10 bar, it remains in a liquid phase over a range of temperatures of up to 50 C.; and a flexible flotation chamber communicating with the compressed gas container through a passage, the passage remaining normally closed until its opening is actuated, thereby allowing the charge to expand into the flotation chamber, and to inflate the flotation chamber, wherein the passage is closed by a stopper held in the passage by a backplate, the backplate being adapted to be separated from contact with the stopper when the device is activated, such that the pressure of the gas in the pressurized gas container is sufficient to eject the stopper.

2. A flotation device according to claim 1, wherein the gaseous material has thermodynamic properties such that when compressed into the container at a pressure of not more than 14 bar, it remains in a liquid phase over a range of temperatures of up to 70 C.

3. A flotation device according to claim 1, wherein the device is adapted to be manually activated by a user.

4. A flotation device according to claim 1, wherein the container occupies a volume of less than 80 milliliters and the charge of gaseous material expands to at least 5 liters when released into the flexible flotation chamber.

5. A flotation device according to claim 1, further comprising a sensor indicative of immersion in water for more than a predetermined time, and providing a signal to activate the inflation device.

6. A flotation device according to claim 1, further comprising a sensor adapted to detect any one of vibration, depth, pressure or light.

7. A flotation device according to claim 1, wherein the gaseous material comprises a Tetrafluoropropene-based hydrofluoroolefin.

8. A flotation device according to claim 1, wherein the gaseous material comprises at least one of R1234ze(E) or R1234yf or R1224yd(Z).

9. A flotation device according to claim 1, wherein the device has a strap configured to enable the device to be worn on any of the wrist, arm, waist, chest or neck of a user.

10. A flotation device according to claim 1, wherein the container has walls constructed of a polymer material of less than 2.5 mm in thickness.

11. A flotation device according to claim 1, wherein the stopper is held in the passage in such a manner that when the device is actuated, a pressure of no more than 10 bar of the gaseous material in the container is sufficient to eject the stopper to enable the pressurized gaseous material to inflate the flexible flotation chamber.

12. A flotation device according to claim 1, wherein the stopper is held in the passage in such a manner that when the device is actuated, a pressure of no more than 14 bar of the gaseous material in the container is sufficient to eject the stopper to enable the pressurized gaseous material to inflate the flexible flotation chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

(2) FIG. 1 shows a schematic cut-away drawing of an exemplary implementation of the emergency flotation devices described in the present disclosure;

(3) FIG. 2 is a table showing the vapor pressure as a function of temperature for one type of gas for use in the device of FIG. 1; and

(4) FIG. 3 is a graph showing the relationship between vapor pressure and temperature for the gas shown in the table of FIG. 2.

DETAILED DESCRIPTION

(5) Reference is first made to FIG. 1, which shows a schematic cut-away drawing of the cross section of an exemplary implementation of the emergency flotation devices described in the present disclosure. The example shown is for a device which is to be wrist or upper-arm mounted, though it is to be understood that similar construction of the operative mechanism may be used for the device to be mounted on any other part of the user's body, by use of the appropriate attaching straps. Examples of other such attachment modes could be for a waist belt application, or for a chest mounted application, with straps attached around the user's body under the arm pits, or for a neck-tie arrangement, with the device supporting the swimmer's head above water. Fixation on the upper arm is used to describe the presently disclosed example of the device. The pressurized gas container 10 is held by means of a flexible strap 11 on the limb to which it is attached, such as by the use of a Velcro fastening section 12, or any other fixation means. The gas container 10 may be constructed of a thin polymeric material such as nylon, and because of the comparatively low pressure of the contained pressurized gas, and the small size of the container, the wall may be as thin as 2.5 mm, or even less depending on the size of the container, thus contributing to a lightweight device. Alternatively, the container may be made of thin metallic foil, or a foil-plastic composite material. Such a thin walled plastic container may therefore also be slightly flexible, such that, if the liquefied gas fills the entire volume, it can expand somewhat with increase in environmental temperature. However, to maintain optimal thermodynamic equilibrium conditions, it would be preferable that the liquefied gas should not completely fill the entire volume of the pressurized gas container, so that the increase in internal pressure of the gas container with increased environmental temperature is minimized.

(6) The pressurized gas container 10 is connected by means of a passageway 15 to the inflatable flotation bag 14, which is protected during storage and when normally used for swimming by a cover 17, which detaches if the bag inflates. The flotation bag 14 is shown for simplicity as a single layer, but it is to be understood that it could have a folded configuration such that a large bag can fit snugly attached to the arm band 11. The passageway can be closed by any means which is gas-tight, but which can be readily removed when the device is activated. In the example shown in FIG. 1, the passageway 15 is closed by means of a simple rubber stopper 13, which is held in place by means of a back-plate 16, held against the bottom face of the gas container 10 by any suitable mechanism, such as a magnetic catch, or a mechanical clasp, or a simple adhesive layer. When the compressed gas container 10 is pulled away from the flexible strap 11 as the user activates the device, in one exemplary implementation, by pulling on an actuating ring attached to a cord, the connection to the back plate 16 is broken, and even the comparatively low pressure of the compressed liquefied gas in the gas container can now eject the stopper 13 into the inflation bag 14, allowing the gas to flow out through the passageway into the inflatable bag 14. The space generated between the gas container bottom surface and the back plate 16 is sealed at its outer edge, as shown at the right hand side of the gap, so that gas flowing out of the gas container cannot escape and is directed only into the inflation flotation chamber 14. The liquefied gas fill expands into the chamber 14, which is at atmospheric pressure, until it is full, typically filling a volume of 5 liters, and is thus capable of supporting an adult user. Larger models can be envisaged for the purpose of supporting more than one person, or a piece of equipment. Devices can also be produced having a smaller charge and volume for use by children. The inflated flotation bag 14, attached to the now empty gas container 10, should be connected to the strap 11, such as by a leash 18, such that the bag supports the limb on which the device is strapped. Although the activation mechanism shown in FIG. 1 is a particularly simple and low cost arrangement, it is not intended to be the only possible mechanism for use with the devices of the present disclosure, and any suitable, simply activated mechanism, may equally well be used.

(7) Reference is now made to FIG. 2, which is a table obtained from a specification document entitled The Environmental Alternative to Traditional Refrigerants, published in 2015 by Honeywell Belgium N. V., showing the vapor pressure as a function of temperature for a new, environmentally favorable refrigerant of the Solstice ze class. This gas is chemically trans-1,3,3,3,-Tetrafluoroprop-1-ene, and has been assigned the nomenclature R-1234ze(E) under the ASHRAF Standard 34 for refrigerants. As is observed in FIG. 2, the boiling point at atmospheric pressure, i.e. at 101.3 kPa, is approximately 19 C., and the vapor pressure at 20 C. is still only slightly more than 4 bar absolute, approaching 10 bar absolute at 50 C. and 16 bar at 70 C. Thus, for instance, the gas fill of R-1234ze(E) will remain in its liquid state at up to 50 C. if the pressure in the gas capsule is maintained at 10 bar, and to 70 C. if the gas capsule can sustain a pressure of 16 bar.

(8) FIG. 3 is a graph showing the relationship between vapor pressure and temperature for the R-1234ze(E) gas shown in the table of FIG. 2.

(9) Another refrigerant gas, (Z)-1-chloro-2,3,3,3-Tetrafluoroprop having similar properties, is also available from AGC Chemicals Inc., of Exton, PA, in the Amolea family, and is designated R1224yd(Z). R1224yd(Z) has a boiling point of 14 C. at atmospheric pressure, and that the fill will remain in its liquid state at a temperature of 50 C. under a pressure of only 3.4 bars, making it even more useful for the device than R-1234ze(E), since the internal pressure required of the pressurized gas container is even less.

(10) Yet another suitable refrigerant gas is R134A, which is chemically 1,1,1,2-Tetrafluoroethane. It is widely used for air conditioning systems, and is significantly cheaper than the previously mentioned gas this. R-134A has a boiling point at atmospheric pressure of 26 C., and its vapor pressure at 50 C. is 13.5 bar, and at 70 C., it is 21 bar. Hence, though requiring a higher pressure capsule, it may be more useful than the previously mentioned Tetrafluoroprop family of gases, for devices which must be rated for storage temperatures of up to 70 C.

(11) The material of the liquefied gas container and of the inflatable flotation bag must be of a composition which is not degraded significantly by the liquid or gaseous fill.

(12) In order to make activation of the device independent of the user's cognitive abilities, or even consciousness, both to which are factors for consideration in designing such a device, the device can be improved by incorporating an automatic activation mechanism. A depth sensor or pressure sensor (e.g., an ultrasonic sensor) may be connected to the inflation device, such that when the sensor reaches a predefined depth for an unreasonable period of time, it automatically activates the inflation device. This enables automatic activation of the device if the swimmer sinks into the water. Alternatively or additionally, the user's pulse or motion pattern may be discerned, and used to assume distress, and to activate the inflation of the device automatically. Such additions would, however, entail a more complex and costly device.

(13) It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.