Life-saving flotation device

Abstract

Lifesaving devices for providing flotation support to their users, and comprising a pressurized gas container, a flotation balloon and a valve for releasing the pressurized gas into the flotation balloon. The method of designing the devices comprises selecting a gas charge for the pressurized gas container, having a high molecular weight, such that, for a specific lifesaving device, the diffusion of the gas charge through the walls of the pressurized gas container are reduced, as compared with a gas charge having a lower molecular weight. The device therefore has a longer shelf life before the need to recharge the gas fill. The use of such a high molecular weight gas also reduces the diffusion of the gas charge through the walls of the flotation balloon, such that the device fulfils its purpose of supporting the user in water for a longer period of time.

We claim: 
     
         1 . A method for increasing the shelf life of a life-saving flotation device, comprising the steps of:
 providing a life-saving flotation device comprising:
 a pressurized gas container; 
 at least one flotation chamber; and 
 an actuating valve connecting the pressurized gas container to the at least one flotation chamber; and 
   selecting a gas fill for the pressurized gas container, the gas having a molecular size such that the diffusion rate of the gas fill out of the pressurized gas container is sufficiently low that the pressurized gas container maintains a predetermined charge of gas for a predetermined minimal time requirement.   
     
     
         2 . A method according to  claim 1 , wherein the gas fill selected has a molecular weight of more than 100 gm/mole. 
     
     
         3 . A method according to  claim 1 , wherein the gas fill selected has a molecular weight of more than 60 gm/mole. 
     
     
         4 . A method according to  claim 1 , wherein the pressurized gas container comprises a single polymer layer. 
     
     
         5 . A method according to  claim 1 , wherein the gas fill selected further results in the at least one flotation chamber maintaining a volume of the gas sufficient to support the user of the device for a predetermined minimum time requirement. 
     
     
         6 . A method according to  claim 1 , wherein the gas fill selected comprises at least one of R1234ze(E), R1234yf, R1224yd(Z) or R515B mixture.