Portable breathable fire extinguishing liquefied gas delivery system

This invention provides a means for transporting and delivering highly effective, breathable fire fighting inert gases to a fire zone, whereby the normally inert gas is transported to the fire in liquid or compressed form.

BACKGROUND OF INVENTION

The most common fire fighting vehicles in use today deliver water to extinguish fires. (Fire trucks, fire boats etc.) Some back-pack or fixed carbon dioxide or chemical systems are used for small fires. When using water for large fires, large quantities are needed. Although water is a useful fire fighting agent for Class 1 (paper and wood) fires, it is slow, and produces much damage to interior structures and equipment etc. In winter freezing of water on hoses and ladders causes problems. Also people must first be removed from burning structures before water can be safely used. Generally, one water hose team of 4 men can extinguish 1200 square feet. For Class 2 fires (oil, gasoline etc.), water is not very effective. Halogen based chemicals such as that available under the brand name Halon, are toxic and also damage equipment. Very large areas, such as entire floors as in the World Trade Center fire, cannot be extinguished using water. For tall buildings, skyscrapers etc the water system depends on internal piping systems which may not always be operational. This invention provides an external, large capacity independent non-toxic, non-damaging fast extinguishing system, which is superior to conventional systems currently used.

In this invention, liquid, cryogenic inert gases are transported to the fire which when converted to gaseous form expand over 700 times at 70° F., and another 4 times at the fire temperature of about 1500° F. A truck carrying 10,000 gallons of liquid will convert to 28 million gallons of gas, which can treat 1800 average size rooms.

Previous patents have disclosed the composition of gases used to extinguish fires, where the oxygen content is reduced (U.S. Pat. Nos. 3,893,514, 4,807,706), and or chemicals are added which impart to the atmosphere heat capacity sufficient to suppress the combustion in the enclosed area (U.S. Pat. Nos. 3,715,438, 3,840,667, 1,926,396). In U.S. Pat. No. 4,807,706, oxygen is reduced and carbon dioxide added into the fire zone, making the atmosphere in the fire zone breathable.

Generally these are fixed in place systems, with means to detect fires and introduce the appropriate gas or chemical, with the agents at room temperature.

This invention comprises liquefying appropriate gases and transporting them to the fire, where the gases are applied directly to the fire in either liquid or gaseous form. This provides an independent external, non-toxic system of fire extinguishing gases which reduce the oxygen content of the enclosed air in the fire zone and /or cools the fuel. The gases permeate into all space quickly, including closed desk drawers, to quickly put out fires.

BRIEF SUMMARY OF THE INVENTION

This invention provides a means for transporting and delivering highly effective fire fighting inert liquid gases to the fire. The inert material can be both breathable, (non-toxic), or toxic. The transport of liquid or gaseous inert gases can be by firetrucks, fireboats, or helicopters. The gas can be carried in liquid form, to maximize the volume of agent being transported to the fire. The inert gas can also be provided using nitrogen generating devices such as pressure swing or membranes systems. At the fire scene the liquids are converted to the gaseous form by a heat exchanger, or by the fire heat if the liquid is applied directly to the fire. The nitrogen and carbon dioxide are mixed in the appropriate ratios to form a breathable fire extinguishing gas mixture, which is then applied to the fire in liquid and or gaseous form. Appropriate conduit and lance systems are used to deliver the gas mix into fire.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a transportable system for delivering a fire extinguishing gas to a fire zone. The system comprises a storage vessel for a normally gaseous inert gas and a delivery means for delivering the inert gas to the fire zone. By inert is meant a gas that does not react under ambient conditions or the high temperatures of the fire zone.

In one embodiment, the storage vessel for the inert material is a cryogenic vessel that stores the inert material in liquid form. Insulated vessels or tanks capable of storing normally gaseous materials in liquid form are well known in the art and available commercially. When the inert material is in liquid form, the system can also comprise a means for vaporizing the inert material prior to delivering or introducing the inert material to the fire zone or the inert material can be delivered directly to the fire zone and vaporized in situ in the fire zone.

In another embodiment of this invention, the inert material is stored in the storage vessel in gaseous form. In this embodiment there is no need to vaporize the inert material prior to introduction into the fire zone.

Preferably, the inert fire extinguishing gas employed in the system of this invention is a breathable mixture that contains carbon dioxide. In such embodiment, the system of this invention also contains a storage vessel for carbon dioxide and a means for mixing the inert gas and the carbon dioxide to form the breathable mixture. In the embodiment wherein the inert gas is stored in liquid form in a cryogenic vessel, the means for vaporizing the inert gas can be located upstream of the means for mixing the inert gas and the carbon dioxide.

As mentioned above, the inert gas can be stored in a gaseous form, in which case the storage vessel for the inert gas can be a pressure vessel of the type well known in the industry for the storage of compressed gasses.

When the system is operating to produce a mixture of inert gas and carbon dioxide, the vessel for storing the carbon dioxide can store the carbon dioxide in a form selected from the group consisting of solid, liquid, gaseous and supercritical forms.

When utilizing carbon dioxide it is within the scope of this invention that the inert material and carbon dioxide mixing zone is located at the end of the delivery means and in the area where the mixture is delivered to the fire zone.

In accordance with this invention the delivery means comprises a conduit which is capable of transporting a cryogenic fluid. Thus, the delivery means can be a rigid telescoping conduit. The delivery means can also be an extendable, flexible, coiled metal conduit.

In the case wherein the fire zone is an enclosed volume and the inert gas is nitrogen, the nitrogen and the carbon dioxide are metered so that the mixture introduced into the fire zone contains from about 88 to about 96% by volume of nitrogen and from about 4 to about 12% by volume carbon dioxide so as to provide a gaseous mixture in the fire zone containing less than about 15% by volume oxygen and from about 2 to about 5% by volume of carbon dioxide. It is preferred that the oxygen content of the gaseous mixture in the fire zone be maintained above about 8%, for example above about 10%. Preferably, the nitrogen content of the mixture introduced is at least about 90% by volume. It is also preferred that the nitrogen concentration is less than about 94% by volume. It is also preferred that the carbon dioxide concentration in the mixture introduced into the fire zone is at least about 6% by volume. It is also preferred that the carbon dioxide concentration be less than about 10% by volume. Replacing about one half of the room volume with the incoming gas mixture will reduce the oxygen content below 15% and quickly extinguish the fire in a matter of minutes. Under certain circumstances air can also be used with the incoming nitrogen and carbon dioxide to flush the fire zone.

The invention consists of three different modes for transporting, mixing, and delivering the inert gases into the fire zone. An all-liquid system, a liquid to gas system, an all gas system.

The all liquid system consist of the vehicle for carrying the cryogenic, inert liquefied gases in insulated vessels at temperatures below minus 320° F., in the range of (−320 to −452° F.). The vehicle can be a truck, boat or helicopter.

The liquefied gas is contained in insulated vessels generally used for holding low temperature cryogenic fluids, and mounted on the vehicle of choice. Attached to the holding vessels are metering pumps generally used for pumping cryogenic fluids. Downstream of the metering pumps is a mixing vessel or unit for mixing the liquid gas with carbon dioxide, which can be solid, liquid, gas or supercritical form. Downstream of the mixing device are pumps for the liquefied gas, to be used if additional pressures are needed for delivery to the fire. Downstream of the mixing system is means for delivering the material to the fire. Such means can be an insulated, telescoping metal conduit for transporting the liquid gases into the fire zone. This conduit can be separate or a part of the vehicle, and can be directed vertically and horizontally. Affixed to the exit end of conduit is a heavy-duty lance for penetrating windows or walls. If materials are in the gaseous form the means for delivering the material can be a flexible conduit. This integrated system delivers liquid gases directly into the fire zone, where the liquid expands into a gas due to the heat of the fire. The gas is 2800 times the volume of the starting liquid. A fire vehicle carrying 10,000 gallons of liquid gas can produce 28 million gallons of fire extinguishing gas in the fire zone. At 7.48 gallons per cubic foot it is equal to 3.7 million cubic feet of gas. A 10′×10′×10′ room is equal to 1000 cubic feet; therefore the system can fill 3,700 rooms or 1850 rooms given 50% loss and the volume needed to reduce oxygen below 15%.

The liquid to gas system converts the liquid inert to the gaseous form in the transmission conduit using a heat exchanger commonly used for cryogenic fluids. This would deliver gases to the conduit, permitting firemen to reach higher levels due the lightweight of the gas system. In this system the liquid gas can pass through a heat exchanger forming the gaseous state, on to the mixing device. Carbon dioxide can be metered into the mixing device as a solid, liquid, gas or supercritical fluid. The mixture can then be fed to the conduit system. The conduit consists of either a rigid telescoping insulated conduit or a flexible coiled accordion metal conduit, with attached lance at the exit end.

The high-pressure gas system contains the gases in high-pressure tubes, 500 to 20,000 pounds per square inch pressure, mounted on the delivery vehicles. These gases are metered into the mixing vessels with carbon dioxide. The high-pressure gases are delivered as above to a flexible conduit and or a lance system for delivery into the fire. Pumps can also be used if higher pressure is needed.

The gases are pumped into the fire zone to reduce the oxygen content below 15% and maintain the carbon dioxide in the 1-3% range.

In the three systems described above the carbon dioxide can be delivered into the process stream conduits, upstream of the conduit and lance, where the inert can be either liquid or gas. The carbon dioxide can be in the solid, liquid, gaseous or supercritical state. The carbon dioxide can also be delivered directly into the fire zone.

The conduit attached to the fire vehicle, can be an insulated, telescoping, rigid metal conduit capable of holding cryogenic liquids or gases. It can also be a coiled accordion metal conduit for added flexibility, and extendibility. The fixed conduit on the vehicle can direct the fluid stream in all directions. The flexible conduit can be manually or mechanically directed.

This unique system has many advantages over existing fire fighting methods as follows:Extinguishes all types of firesRemoves heat from the fuel and reduces oxygenPeople and animals trapped in the fire can breath the mixture giving them more time to escapeHigh rise buildings are accessibleSince the system rapidly extinguishes fires, it reduces fire spread, pollution, and enhances the safety of the fire fightersThe cold gases protect the conduit system from fire heat.Fire fighters would have coolant protection at the fireThe use of helicopters allows accessibility to high floorsInert material used is low costHelicopters can be quickly sent to ships not in port

DESCRIPTION OF DRAWINGS

InFIG. 1is shown a fire vehicle110with integrated system for transporting and delivering a fire extinguishing mixture to a fire zone. The vehicle can be a truck, boat or helicopter. An insulated vessels for holding cryogenic fluids118, is mounted on the vehicle110, as well as vessels for holding carbon dioxide in solid, liquid, gaseous or supercritical state112. These vessels are connected via insulated conduits to pumps and mixers114, and then to an extendable, insulated, rigid, adjustable metal conduit116. At the end of the conduit is a metal lance120for penetrating windows and walls.

InFIG. 2is a cryogenic liquid system showing the components of this integrated system. The insulated vessel210is connected to metering pump212, used for moving cryogenic fluids, by means of line211. The pump212is connected to mixing vessel214by means of line213. Carbon dioxide holding vessel216is connected to mixing vessel214by means of metering line215. The carbon dioxide can be in solid, liquid, gaseous or supercritical state. The mixing vessel214is connected to pump218by means of line217, for moving the fluids. The pump218is connected to the conduit and lance system220by line219, which deliver the fluids into the fire zone222. Carbon dioxide from vessel224can also be introduced directly into the222, as illustrated by line223or carbon dioxide from vessel216can be introduced directly into the fire zone222by means of line225.

FIG. 3is a cryogenic liquid to gas system. Vessel310and pump312are the same as vessel210and pump212in FIG.2. Liquid inert material from vessel310is passed via line311to metering pump312and then pumped via line313to the heat exchanger314, and converted into the gaseous state. The gas is transported via line315to the mixing vessel316along with metered carbon dioxide from318. The mixture from mixing vessel316is transported to the conduit and lance system322as illustrated by line319and into the fire zone324as illustrated by line321. Carbon dioxide from vessel318and br326can be either solid, liquid, gas or supercritical state. If needed an auxiliary pump320can be used to increase the pressure of the gas mix prior to introduction to the conduit and lance system322. Carbon dioxide can also be fed directly into the fire zone324from separate carbon dioxide storage vessel326, as shown by line323. Carbon dioxide from vessel318can also be introduced separately into the fire zone324illustrated by line325.

FIG. 4is a high-pressure inert gas system for holding and delivering the fire extinguishing gas into the fire. High-pressure gas tubes410contain inert gases e.g. nitrogen, at pressures of 500 to 20,000 pounds per square inch. High-pressure gas tubes410can also contain carbon dioxide. The inert gas is transported and metered to the mixing vessels412via line411, along with the metered carbon dioxide414via line413. From the mixing vessels412, the flow of gases through420is the same as inFIG. 3from316through324.

The mixture of gases is transported via line415to the flexible conduit and lance418, and thence to the fire zone420as illustrated by line417. Carbon dioxide the storage vessel422can be applied directly to the fire zone420as illustrated by line419. If needed auxiliary pump416can be used to increase the pressure of the gas mixture delivered to the flexible conduit and lance418.

InFIG. 5is shown a detailed illustration of the adjustable metal conduit116shown in FIG.1. In this figure is shown an extendable metal tube510for delivering an incoming stream of inert material511and delivering it as513into the fire zone. The tubes are insulated with high value insulation and or a vacuum in the peripheral shell512. The extendable portions illustrated as514and515, are movable axially, so the inert stream513can be directed proximate and into the fire zone.

FIG. 6shows a flexible, coiled, extendable, accordion conduit for delivering a mixture comprising a normally gaseous inert material, such as nitrogen, and carbon dioxide to a fire zone. The conduit has an inlet end611for admitting the mixture and an outlet end for delivering the mixture to the fire zone. The conduit, as illustrated, is composed of a series of interconnected coiled accordion members612. At the top ofFIG. 6the members612are shown in a closed position, such as would be used when the system is being transported to a fire zone. At the bottom ofFIG. 6the members612are illustrated in an extended position, such as would be used when delivering the mixture to a fire zone. Thus, the conduit of this Figure is compact for transportation and can be extended to deliver the mixture to the fire zone at some distance remote from the vehicle upon which the system can be mounted.