The present invention relates to a fire extinguishing composition.

Historically, fires are among the main causes of natural and nonnatural catastrophic events. Systems to contain their harm to people, property and the environment have been developed in order to contrast their consequences.

The first means used to carry and spread water to extinguish fires were conceived and built as early as 200 BC. The development of firefighting systems has continued at the same rate as industrial development, such as for example with the construction of railroad networks at the beginning of the nineteenth century, which required the transport of dangerous goods such as gunpowder, dynamite sticks and liquid nitroglycerin. Indeed, the first portable powder fire extinguisher, containing approximately 14 liters of pearl ash and pressurized with compressed air, was developed in 1818. Moreover, the increase in the quantity and ease of transport of electrical and electronic devices is evolving constantly.

This development cannot occur without the availability of fixed and portable systems that allow to store electric power, by means of batteries, both for domestic use and for industrial use. The production, use, reuse and disposal of storage systems therefore becomes increasingly important, and so do the risks linked to each step of the life cycle of these systems.

The lithium contained in rechargeable batteries is a substance which upon contact with water generates flammable and explosive gases which are toxic for human beings and for the surrounding environment.

Safety workers have long noted and extensively documented the danger in the use and management of lithium ion batteries.

The dangers are present during every phase of the life of a battery, such as for example use, charging, transport, sorting, splitting and recycling. In summary, the greatest risks in the use of new-generation batteries are the spontaneous ignition of fire, explosion, repeated reinignition even after extinguishing and the emission of toxic gases.

The high temperatures reached during combustion can be lethal for people and can damage irreparably the surrounding structures. The gases released by combustion are toxic and can have severe consequences in the short and long term on people.

In fire containment and extinguishing operations, the extinguishing agents that are normally used can contaminate nearby people and the environment and can also permanently compromise the apparatuses involved, in addition to preventing their recyclability.

Multiple extinguishing agents and containment systems are currently used to mitigate the risk of fire associated with lithium batteries. For example, containers are used for recovery, transport and storage, including quarantine, for this type of battery and device. These containers are equipped with fire detection and extinguishing systems.

Devices that allow active detection and extinguishing in case of fire of the goods arranged inside containers are essentially of two types. The first type of device is used in the parking and storage phase. During this phase, the container is connected to the water mains by virtue of hydrants or hose reels, i.e., a firefighting apparatus constituted by a mobile reel on which a semirigid hose is wound which is connected, at one end, to a dispensing nozzle. The second device is an automatic aerosol system which is activated both during parking and during transport.

These second-generation containers follow the first-generation ones, which consist of mobile containers with an upper opening, so-called “open top” containers, in which the vehicle is immersed completely in the water contained in the container and left in quarantine until combustion extinguishes the combustible substance of the battery.

Both of the extinguishing systems cited above have important limitations; on the one hand, aerosol systems extinguish the fire within seconds but do not avoid reinitiation. In the specific case of lithium batteries and depending on the powder used, the aerosol system is capable of ensuring from a minimum of 30 minutes to a maximum of 3 hours of absence of fire. On the other hand, the water-only system requires important quantities of liquid, which during use is contaminated by the dangerous substances contained and released by the batteries during combustion and at the end of each use must not be dispersed into the environment but must be entirely collected and decontaminated, generating at each use a non- negligible risk of contamination of the environment and a high decontamination cost.

In view of the limitations described above, the aim of the present invention is to provide an extinguishing composition that allows to extinguish a fire with a lower consumption of water and without producing toxic fumes.

Within the scope of this aim, an object of the invention is to provide an extinguishing composition that allows to extinguish a lithium battery fire without reignition phenomena.

This aim, as well as these and other objects which will become better apparent hereinafter, are achieved by a fire extinguishing composition comprising an encapsulating agent and water with the addition of a gas selected from CO ₂ and an inert gas.

The aim and objects of the present invention are also achieved by the use of the extinguishing composition according to the invention to extinguish a combustion process.

Further characteristics and advantages of the invention will become better apparent from the detailed description that follows.

In a first aspect, the present invention relates to a fire extinguishing composition comprising an encapsulating agent and water with the addition of a gas selected from CO ₂ and an inert gas.

The inventor of the invention has surprisingly found that the mixing of an encapsulating agent with water with pre-added gas allows to obtain a foam with a higher extinguishing effect than obtained by dispensing the same encapsulating agent mixed with water without pre-added gas.

Preferably, the extinguishing composition comprises said encapsulating agent in a quantity comprised between 0.5% and 9% by volume on the total volume of the composition.

The encapsulating agent is preferably a water-based mix of at least one surfactant selected from the group consisiting of ionic surfactants and non-ionic surfactants.

In a preferred embodiment of the extinguishing composition according to the invention, the encapsulating agent comprises 1% to 5% by weight of n-decanol, 2% to 8% by weight of n-octanol, 25% to 35% by weight of coconut fatty acid methyl esters, and 52% to 72% water, each on the total weight of the encapsulating agent.

Coconut fatty acids are a mixture of fatty acids that typically has the following composition:

- 0.1 to 0.95% by weight of hexanoic acid;

- 4 to 10% by weight of caprylic acid;

- 4 to 8% by weight of capric acid;

- 45 to 56% by weight of lauric acid;

- 16 to 21% by weight of myristic acid;

- 7.5 to 10.2% by weight of palmitic acid;

- 2 to 4% by weight of stearic acid;

- 4.5 to 10% by weight of oleic acid;

- 0.7 to 2.5% by weight of linoleic acid;

- traces of alpha-linoleic acid, arachidic acid and gadoleic acid.

The extinguishing composition according to the invention comprises 91% to 99.5% by volume on the volume of the composition of water with the addition of a gas selected from CO ₂ and an inert gas. Preferably, the gas is in a quantity comprised between 1.5% and 8% by volume, more preferably between 1.7% and 2% by volume on the volume of the water.

The extinguishing composition according to the invention can furthermore comprise ions selected from potassium (K ⁺ ) in a quantity comprised between 0.7 and 3 mg per liter of composition, and sodium (Na ⁺ ) in a quantity comprised between 7 and 21 mg per liter of composition.

In one embodiment, particularly for extinguishing liquid fuel fires, the composition according to the invention furthermore comprises a powder selected from cork powder and vermiculite (or perlite) powder with a particle size comprised between 0.1 and 0.5 mm in diameter.

In a second aspect, the invention relates to the use of the extinguishing composition according to the invention to extinguish a combustion process, particularly to extinguish a lithium battery combustion process.

The invention is now described with reference to the following nonlimiting examples.

EXAMPLE 1: PREPARATION OF THE EXTINGUISHING COMPOSITION

10 liters of water with added gas were prepared by using distilled water with added CO ₂ gas, one liter at a time, by means of a commercial Sodastream® device for the home production of carbonated water. 9.4 liters of carbonated water thus obtained received the addition, in a plastic container with a capacity of 15 liters, of 0.6 liters of encapsulating agent comprising 1% to 5% by weight of n-decanol, 2% to 8% by weight of n- octanol, 25% to 35% by weight of coconut fatty acid methyl esters, and 52% to 72% water, each on the total weight of the encapsulating agent.

The composition thus obtained was used to fill a 6-liter HNE HiGUARD 2 device (HNE Technologic AG) according to the manufacturer's instructions. The device was then pressurized with CO ₂ to a pressure of 3.8xl0 ⁶ Pa. EXAMPLE 2: LITHIUM BATTERY EXTINGUISHING TEST

To perform the test, only the upper part of the cardboard packaging of a battery pack/module was removed. Then, to allow the insertion of an initiator at the center of the pack/module, one of the 100 Samsung 0.95 kW cells (INR18650-29E) that compose it was removed. The pack, without the lid of the packaging and with the initiator inserted at the center, was placed inside a steel “Box Test” container provided with an upper lid provided with holes to allow the passage of the wires of the initiator and provided with a bolt-type closure device. After connecting the wires to the initiator, two steel plates having the same dimensions as the “Box Test” container were placed above the pack/module with a 2-mm gap for the passage of the initiation wires. The “Box Test” container was then closed hermetically and fixed with bolts. In this manner the condition of the housing that contains and protects batteries in vehicles, generally made of steel or aluminum, was reproduced as faithfully as possible. Moreover, this simulation allows to avoid quenching by drowning and to test the actual effectiveness of the extinguishing preparation and of its diffusion system.

The “Box Test” container, with the pack inside it, was deposited inside a 600-liter ADR-approved ASP container made of steel with an overpressure valve. 8 nozzles with 0.1-mm front exit holes, fed by 0.8-mm aluminum tubes, were mounted inside the ASP container (8 exit holes in total). The supply tubes were connected to a quick coupling located outside the container and connected to the 6-liter backpack CAFS device (HNE HiGUARD 2, HNE Technologic AG) of example 1, i.e., an extinguisherlike device with a cylinder which can be carried as a backpack and allows the atomization of the content, increasing the contact surface, reducing the size of the droplets of the extinguishing compositions, which can even be just water (in this case, the extinguishing composition prepared in Example 1). The CAFS device, as described in Example 1, was filled with extinguishing composition constituted by 6 liters of water with added gas, comprising 6% by volume of encapsulating agent. Then the CAFS device again received the addition of CO ₂ to be pressurized according to the instructions of the manufacturer, which, differently from the test, uses only compressed air for pressurization, reaching a pressure that varies from 2.2xl0 ⁶ Pa to 3.8xl0 ⁶ Pa.

1 minute and 17 seconds after initiation, the blows produced by the ignited batteries were detected and the CAFS device was activated manually by means of the adapted lever of the nozzle. At 2 minutes and 10 seconds, the smoke exiting from the overpressure valve was found to be completely white, i.e., 53 seconds after the activation of the CAFS device filled with the extinguishing preparation the test was considered over and the 600-liter ASP container was opened for inspection. Using firefighter gloves, the “Box Test” container containing the cells was removed from the container and opened. All the cells were found to be dry (no quenching by drowning) and only 12 cells were found "open" and broken while the adjacent ones remained intact.

All the cells were then quarantined inside a specifically provided bin, which in turn was deposited inside an ASP container armed with an aerosoltype automatic extinguishing system. Daily inspections allowed to observe that even one month after the execution of the test no spontaneous reignition of the cells had occurred.

In practice it has been found that the device according to the invention fully achieves the intended aim, since it allows to extinguish a fire, and particularly a lithium battery fire, without producing toxic fumes and without reignition phenomena.

Although the device according to the invention has been conceived in particular for lithium battery fires, it can in any case be used more generally to extinguish fires.

The fire extinguishing composition thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, as well as the dimensions, may be any according to the requirements and the state of the art.