Gas generating processes based on the decomposition or burning of chemical propellants are frequently used for a number of purposes, e.g. for the inflation of inflatable devices, such as airbags, life boats or life vests, for operating pneumatically driven devices, or for use in fire-extinguish devices.
Known chemical methods for obtaining relative cool gases are generally based on the decomposition or the burning of solid materials in special units. These materials are generally shaped in the form of a solid block of material or as (loosely) packed powder, loose granules or loose tablets. The hot gases generated from the decomposition of these materials are in general cooled with the aid of special chemical cooling agents or by specific designed features such as heat exchangers. The high temperature burning gases are passed through the layer of the cooling agent or the heat exchanger and the temperature of the gases decreases as a result of the endothermal decomposition process of, or heat absorption by the cooling agent. Such processes are described for instance in GB-A 1,371,506.
In RU 2108282 it is observed that one of the drawbacks of the hitherto known art as cited above is the relatively complicated structure of these units. Another drawback is that the known gas generators did not allow or provide for the gases to be cooled below 150° C., which limits the applicability of such gas generators to systems that can withstand such high temperatures. Further disadvantages include the formation of relatively large quantities of undesired side-products, e.g. carbon monoxide (CO) or nitrogen oxides, a large mass and large size of the generator. For nitrogen gas generators RU 2108282 has the drawback of a reactive slag remaining after usage. This reactive slag requires controlled dismantling of the used gas generator, which make them less suitable for consumer products.
WO 01/23327 proposes a gas generating device for effectively generating nitrogen gas of a low temperature, in order to overcome the above drawbacks.
Accordingly, the gas generator of WO 01/23327 comprises at least one first body, comprising means for the generation of (nitrogen) gas, and at least one second body, comprising means for the generation of a neutralisation agent, wherein means are present for contacting the said neutralisation agent with the said first body, to neutralise the reactive reaction products (slag) from the generation of gas in the said first body, and wherein means are present for operating the generation of a neutralisation agent in the second body at a temporal and/or spatial interval from the generation of gas in the first body.
WO 03/009899 relates to a cool oxygen chemical gas generator, which allows the production of oxygen gas at a temperature below 50° C. Although this generator may serve as an alternative to nitrogen in some applications, the reactivity of oxygen can be disadvantageous or make the generated gas unsuitable for a specific purpose. In general, the gas cannot be used in fire extinguisher applications, and may contribute to oxidation reactions, e.g. corrosion of materials that come in contact with oxygen.
There is a need for an alternative to a gas generator for nitrogen or oxygen cool gas.
It is an object of the invention to provide such an alternative, in particular such alternative that overcomes one or more drawbacks of the gas generators mentioned in the above identified documents.
It is in particular an object to provide a gas generator that is suitable to generate relatively cool gas, comprising no or a relatively low amount of toxic or hazardous components.
It has now been found possible to provide a gas generator suitable to generate relatively cool gas mainly consisting of a different gaseous molecule than nitrogen.