RU2549862C1 - Fire-extinguishing composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to water solutions of a foaming agent based on surface-active substances (SAS) and intended for extinguishing solid combustible materials, combustible liquids and highly-inflammable liquids both in open spaces, and in premises under low temperature conditions. A water-based fire-extinguishing composition contains a film-forming foaming agent based on organofluoric acids and a lithium chloride-based additive, reducing the freezing temperature of the fire-extinguishing composition, and the additive includes carbamide with the following component ratio, wt %: lithium chloride- 26÷29%; carbamide - 8÷12%; film-forming foaming agent - 14÷20%; water - the remaining part.

EFFECT: increased frost resistance of the fire-extinguishing composition without the solid phase sedimentation and reduction of fire-extinguishing efficiency.

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Description

Technical field

The invention relates to aqueous solutions of a foaming agent based on surfactants and is intended for extinguishing solid combustible materials, flammable liquids and flammable liquids both in open space and indoors at low temperatures (up to minus 52 ° C).

State of the art

From the patent RU 2157710 known fire extinguishing composition containing a surfactant 12 ÷ 24 weight. %, higher fatty alcohol (C ₆ -C ₁₂ ) - 1.5 ÷ 3.0 weight. % and water. In order to increase frost resistance and reduce corrosion activity, ammonium acetate is introduced into the composition of the foaming agent in an amount of 10 ÷ 52 weight. %

However, due to the introduction of ammonium acetate, there is a decrease in the stability of the foam, its film formation, and thereby the fire extinguishing efficiency of the composition is reduced.

Known extinguishing composition described in international application WO 0147604 (IPC ⁷ A62D 1/02, published 05.07.2001). This composition is prepared from a film-forming foaming agent based on organofluoric acids (an AFFF type foaming agent), to which a 50–60% aqueous solution of potassium acetate and ethylene glycol (propylene glycol) are added in an amount of 15–20 weight to reduce the freezing temperature. % The composition does not freeze to -50 ° C.

However, this composition does not form a film on the surface of flammable liquids at temperatures below -1 ° C and therefore loses extinguishing effectiveness at low temperatures.

The closest analogue (prototype) of the patented invention is a water-based extinguishing composition containing a film-forming foaming agent based on organofluoric acids (AFFF type foaming agent) and a salt additive, in particular, based on lithium chloride, which reduces the freezing point of the extinguishing composition described in patent RU 114612 (IPC A62C 31/02, publ. 04/10/2012).

The prototype forms a stable insulating water film on the combustion surface that prevents the flow of oxygen from the atmosphere to the ignition site and the evaporation of volatile substances into the environment. However, the prototype composition is functional only up to -35 ° C. Moreover, the most frost-resistant composition (using lithium chloride LiCl as a salt additive) at -20.5 ° C forms a solid crystalline hydrate with water, which limits the flow area of the device supplying the composition to the combustion zone.

The problem solved by the patented invention is the creation of a composition that forms a stable insulating water film on the surface of the combustion, preventing the flow of oxygen from the atmosphere to the ignition site and the evaporation of volatile substances into the environment, which can be stored and operated without falling into the solid phase and reducing fire extinguishing efficiency in wide temperature range up to -52 ° С.

Disclosure of invention

The technical result achieved by using the invention is to increase the frost resistance of the extinguishing composition to -52 ° C without precipitation of the solid phase and reduce fire extinguishing efficiency.

This technical result is achieved by a water-based fire extinguishing composition containing a film-forming foaming agent based on organofluoric acids and a complex additive that reduces the freezing temperature of the solution without the formation of crystalline hydrate. The complex additive includes lithium chloride LiCl and urea H ₂ NCONH ₂ . In this case, the following mass ratio of components should be provided:

Lithium chloride - 26 ÷ 29%;

Urea - 8 ÷ 12%;

Film-forming foaming agent - 14 ÷ 20%;

Water is the rest.

The implementation of the invention

Organofluoric acid-based foaming agents are used as the film-forming foaming agent, for example PO-6A3F, Light Water, Sthamex-AFFF, RUHE-AFFF and the like.

The addition of urea H ₂ NCONH ₂ eliminates the formation of lithium chloride crystalline hydrate. In aqueous solutions, urea is almost completely hydrolyzed to NH ₃ and CO ₂ as H ₂ NCONH ₂ + H ₂ O↔ (NH ₃ ) ₂ + CO ₂ . In the presence of NH ₃ in the aqueous solution of lithium chloride, [Li (NH ₃ ) ₄ ] ⁺ ions are formed in it, which prevent the bonding of lithium chloride and water to crystalline hydrate.

The lower limit of the content of lithium chloride LiCl (26%) provides an operating temperature of -52 ° C, regardless of the type of film-forming foaming agent.

The upper limit of LiCl concentration (29%) together with the lower limit of urea concentration (≥8%) prevents the formation of solid particles of LiCl · 5H ₂ crystalline hydrate or precipitated LiCl salt in solution.

The upper limit of the urea content (12%,) is due to the fact that an increase in the weight of urea reduces the amount of water in the solution, which reduces the quenching efficiency of class A foci.

The lower limit of the concentration of film-forming foaming (14%) prevents the loss of fire extinguishing efficiency due to a decrease in the foam ratio.

The upper limit of the concentration of the film-forming foaming agent (20%) is due to the fact that with an increase in this value there is a slight increase in the multiplicity of the foam, but film formation sharply decreases, which impairs the quenching of combustible liquids (class B), although it does not affect the quenching of solids (class A).

The process of preparing a fire extinguishing composition with the indicated weight ratios of the components is illustrated by the following example.

Suppose, for example, you want to prepare 1 kg of extinguishing agent with the minimum values of the components used.

80 grams of urea, 140 grams of film-forming foaming agent, 260 grams of lithium chloride (anhydrous) and 520 grams of water are measured by weight. A foaming agent is poured into the water and urea is poured. After that, lithium chloride is added to the solution and mixed thoroughly. Then the solution is filtered to exclude substances from it in the solid phase.

If lithium chloride is used as the primary crystalline hydrate LiCl H ₂ O, then 140 grams of foaming agent and 80 grams of urea will require 403 grams of water and 377 grams of LiCl H ₂ O. In this case, the foaming agent, urea, and then LiCl H ₂ O are successively dissolved. .

The results of experimental verification at low temperatures of the compositions with an AFFF foaming agent are presented in the table.

The table shows that the solutions with the claimed content of the components (examples 2 and 5) in their fire extinguishing characteristics (6A and 183B) are not inferior to the prototype (example 1), and at the lowest possible temperature of use (-52 °) it is significantly superior, and solutions with the content of components beyond the stated limits (examples 3, 6 and 7), inferior to the prototype either in fire extinguishing characteristics or at the lowest possible temperature of use.

Claims (1)

A water-based fire extinguishing composition containing a film-forming foaming agent based on organofluoric acids and an additive based on lithium chloride, which reduces the freezing point of the fire extinguishing composition, characterized in that the additive includes urea in the following ratio of components in wt.%:
Lithium chloride - 26 ÷ 29%;
Urea - 8 ÷ 12%;
Film-forming foaming agent - 14 ÷ 20%;
Water is the rest.