RU2699752C1 - Liquid fire-extinguishing composition for fire extinguishing of class d1 - Google Patents

Abstract

FIELD: fire safety.

SUBSTANCE: invention relates to means for fire extinguishing, in particular, to liquid fire-extinguishing compositions intended for quenching of light metals and alloys based on them, belonging to subclass D1. Fire extinguishing liquid composition for fire extinguishing of D1 class includes tribasic copper sulphate in concentration of 10–15 wt%, aluminum sulphate – 5–15 wt%, ammonium water – 5–10 wt%, alkali metal (sodium or potassium) sulphate – less than 5 wt%, the rest – water as a solvent. Composition can additionally contain surfactants in an amount of up to 10 wt%.

EFFECT: invention is aimed at improvement of efficiency of fire extinguishing of light metals due to creation of complex effect of quenching, caused by inhibition of burning metal, stopping oxygen access and cooling simultaneously, which provides reduced consumption of fire extinguishing agent, faster quenching, as well as the possibility of extinguishing volume fires.

1 cl

Description

The invention relates to means for extinguishing fires, in particular to liquid extinguishing compositions for extinguishing fires of class D1. This tool is designed to extinguish light metals and alloys based on them, belonging to subclass D1 according to GOST 27331-87. Such metals include light metals (with the exception of alkali) - magnesium, aluminum, titanium and their alloys, where one of these metals is selected as the main one.

Such a liquid fire extinguishing composition is a homogeneous solution containing basic copper sulfate, aluminum sulfate, ammonia water, alkali metal sulfate (sodium or potassium), the rest is water as a solvent. Surfactants may be additional components.

Almost all modern fire extinguishing compositions for class D1 fires are powders of various compositions designed to fill the burning fire sites, and therefore provide only extinguishing due to the cessation of oxygen access to the burning material without a significant cooling effect or chemical inhibition of the metal, and also implement only the surface method extinguishing. For this reason, they have a relatively low efficiency in extinguishing bulk fires of large structures, porous metal materials or with a developed complex surface (chip scrap, metallurgical slag, fine powders), since a very large amount of fire extinguishing powders is required for filling to achieve a fire extinguishing effect. In addition, such powders do not always provide complete suppression of combustion, since light metals can burn in an oxygen-free environment (without air access) in the presence of nitrogen, carbon dioxide, in the presence of oxidizing agents (for example, termite mixtures) [1]. The absence of inhibition (chemical passivation) can also cause secondary ignition of the extinguished material in case of violation of the integrity of the layer of fire extinguishing powder on it. In addition, powdered extinguishing agents are difficult to supply to the combustion zone - it is impossible to provide a delivery range of more than 3 meters for primary means, and a special telescopic dampener for the powder is required. This greatly limits the range of application of powdered extinguishing compositions, reduces their effectiveness and requires high security measures for personnel of fire departments and employees of specialized enterprises.

Known powdered fire extinguishing compositions often contain components that cause the release of undesirable gaseous products - for example, the use of alkali and alkaline earth metal halides, other halogen-containing substances (for example, borofluorates and borchlorates, various organic substances) that decompose with the release of toxic gases and vapors. In addition, many inorganic salts serving as such components contain crystallization water, which, when heated, is released and upon contact with burning metals can locally accelerate their oxidation with the possibility of sparks, which at the initial stage of their introduction inevitably causes a rise in flare-up. Substances that can decompose with increasing temperature to 300-400 ° C with the release of water vapor (for example, boric acid, borates of alkali and alkaline-earth metals, a number of organoboron compounds) have the same disadvantages. Sodium and potassium carbonates are also very hygroscopic, and when they decompose, carbon dioxide is released that enhances combustion. Such components, for example, are used in the compositions of fire extinguishing compositions in US Pat. US No. 4915853 04/10/1990, US Pat. US No. 5626787 of 03/06/1997, US Pat. RF №2095103 from 10.11.1997, US Pat. WO 1999026698 dated 06/03/1999.

Similarly, the components used in the Russian fire extinguishing powders PHC, Vekson, GTS-1, etc. mainly contain sodium chloride, potassium chloride, soda ash, graphite, and metal borates [2, 3].

The use of water-based liquid formulations is largely ruled out because water reacts with light metals when they burn, releasing hydrogen, which ignites with the explosion. Similarly, organic liquid substances, most of which are flammable, intensify combustion or lead to explosion upon contact with burning metals.

In order to suppress hydrogen evolution in the case of using aqueous solutions, an inhibitor should be used that excludes the evolution of hydrogen or ensures its dilution to safe concentrations.

An extinguishing fluid described in US Pat. RF No. 2310421 dated 11/20/2007, including sulfates, chlorides, ammonium and sodium carbonates and urea, as well as foaming agents, which, when released into the combustion zone, lead to intensive emission of carbon dioxide and ammonia, decomposing to nitrogen, serving as a diluent and providing heat dissipation .

The closest analogue to the intended purpose and composition of the invention may be US Pat. US No. 5660763 from 08/26/1997, which uses aluminum sulfate, various inorganic and organic salts of sodium, potassium and ammonium, as well as excipients, leading to the above-described effect of dilution and heat removal.

However, the intensive release of carbon dioxide during the decomposition of such compositions described in these patents is able to maintain and in some cases enhance the combustion of magnesium and other metals [1], and also does not solve the problem of inhibiting the surface of a burning metal. In addition, these inventions are not without drawbacks due to the use of halides capable of forming, at high temperature, very toxic products together with organic substances that pose a serious danger to humans and the environment.

The composition of the extinguishing liquid proposed in the invention eliminates the evolution of hydrogen from the aqueous base, since a special inhibitor, tribasic copper sulfate (suspension 345 g / l), widely used in agriculture as a fungicide, is used as one of the main components. This compound belongs to substances of hazard class 3 according to GOST 12.1.007-76, and when in contact with a burning metal chemically passivates it, since the electrochemical potential of copper is greater than that of hydrogen. Those. when this compound gets on a burning light metal, copper metal, rather than hydrogen, is restored, while freshly deposited copper blocks the access of oxygen and other oxidizing agents to the metal itself, reliably isolating it and creating a non-combustible film on it.

To increase the solubility of the tribasic copper sulfate used in the composition, concentrated ammonia water (aqueous ammonia in accordance with GOST 9-92) is used, which excludes precipitation due to the complexation of ammonia with copper ions. In this case, ammonia, present in a small amount in the composition of the reaction products, decomposing to nitrogen, provides additional heat dissipation.

Sulfates of aluminum, sodium or potassium also serve as diluents with high solubility in water, while they increase the temperature threshold of decomposition of other compounds, excluding the release of hazardous sulfur-containing compounds. Aluminum sulfate also acts as a pH regulator of the composition. The following examples are used: aluminum sulfate - 18-aqueous aluminum sulfate according to GOST 3758-75 or technical purified aluminum sulfate according to GOST 12966-85, potassium sulfate according to GOST 4145-74, sodium sulfate according to GOST 4166-76.

To improve the rheological characteristics (viscosity, spreadability), any water-soluble surfactants in an amount not exceeding 10% by mass, not causing precipitation of the main components of the fire extinguishing composition, can be additionally applied in the composition. As examples of such surfactants, liquid potassium soap, salts of higher fatty acids of ammonium, sodium or potassium in concentrations below the critical micelle concentration, chlorides or quaternary ammonium sulfates can be given.

The concentration limits of the content of copper, aluminum, sodium and potassium compounds in the composition are selected based on the range of their joint solubility to ensure maximum composition efficiency. The value of the concentration limits of ammonia water is equal to or exceeds stoichiometric up to 2 times with respect to tribasic copper sulfate to ensure its complete solubility. The maximum concentration of surfactants is determined based on their solubility and the effectiveness of providing targeted consumer characteristics of a fire extinguishing fluid.

The use of liquid fire extinguishing compositions according to the present invention provides a number of advantages compared to powdered agents and analogous liquids, since it has the following consumer qualities and parameters:

- providing the possibility of reliable fire fighting class D1;

- reduction of quenching time;

- reduction of extinguishing agent consumption to indicators less than 12 kg / m;

- elimination of the risk of re-ignition;

- providing the ability to extinguish volumetric fires (including elements of large-sized structures);

- complete explosion safety due to the inhibition effect;

- providing the possibility of remote fire extinguishing;

- quenching of metals in various state of aggregation (solid, melt) and form (powders, shavings, compact products, etc.).

- low hazard to humans and the environment;

- cost characteristics of products are competitive with respect to the cost of analogues, taking into account their consumption and other technical and operational characteristics.

The physicochemical nature of the composition based on the selected components provides simultaneous chemical inhibition of the surface of burning light metals, preventing their possible interaction with other substances, eliminates the access of oxygen and other oxidizing agents due to film formation, is accompanied by a very high heat dissipation due to the removal of gaseous decomposition products, which leads to its high efficiency. Also, the composition provided in the invention is stable during storage and does not contain substances emitting any toxic fumes during its use, which significantly improves the environmental component.

All components of the extinguishing fluid in the invention are available and inexpensive, which gives a significant advantage compared to analogues. The use of such extinguishing fluid can significantly increase the fire safety of any objects where there is a risk of fires of class D1.

Examples of fire extinguishing fluid formulations:

* - applied liquid potash soap

** - applied tetraethylammonium chloride

Literature:

[1] Malinin V.I., Serebrennikov S.Yu. Berbek A.M. Analysis of the combustion characteristics of powdered metals in mixtures with air, water and carbon dioxide // M.: POZHNAUKA, Journal of Fire and Explosion Safety, 2010 - v. 19 No. 4, from 12-17.

[2] Baratov A.N., Vogman L.P. Fire extinguishing powder formulations. M: Stroyizdat 1982

[3] Nadubov V.A., Baratov A.N., Vogman L.P. Fire extinguishing powders. - M.: VNIIPO, 2014.

Claims (4)

1. Water-based fire extinguishing liquid for extinguishing class D1 fires, including aluminum sulfate, sodium or potassium sulfates, characterized in that it additionally contains tribasic copper sulfate and ammonia water in the following ratio, wt.%: Tribasic copper sulfate (suspension 34.5%) 10-15 Ammonia water (25% aqueous solution) 5-10 Aluminum sulphate 5-15 Sodium or potassium sulfate ≤5 Water Rest 2. Fire extinguishing liquid according to claim 1, characterized in that it further comprises water-soluble surfactants in the following ratio of components, wt.%: Tribasic copper sulfate (suspension 34.5%) 10-15 Ammonia water (25% aqueous solution) 5-10 Aluminum sulphate 5-15 Sodium or potassium sulfate ≤5 Surfactant ≤10 Water Rest