RU2675863C1 - Fire extinguishing powder compound - Google Patents

Abstract

FIELD: fire safety.SUBSTANCE: invention relates to fire and industrial safety, in particular to compositions of fire extinguishing powders used to extinguish solid combustible substances and materials, as well as liquid and gaseous substances both in closed spaces and in the open air and providing effective extinguishing of fires of classes A, B, C, D. Extinguishing powder composition includes calcium carbonate 30–45 wt.%, zinc carbonate 40–45 wt.%, aluminum oxide 8–10 wt.%, silicon dioxide (Aerosil) 6–10 wt.% and carbon (highly dispersed colloidal graphite) 1–5 wt.%.EFFECT: technical result consists in better extinguishing ability of the powder and universality of use.1 cl, 5 tbl

Description

The invention relates to fire and industrial safety, in particular to the compositions of fire extinguishing powders used for extinguishing solid combustible substances and materials, as well as liquid and gaseous substances both in closed spaces and in the open air and providing effective fire fighting classes A, B, C, D.

The invention provides an increase in extinguishing efficiency and expands the range of materials used as active components of fire extinguishing powders.

Known extinguishing suspension composition based on calcium carbonate (patent RU 2414273 C2, A62D 1/00, publ. 20.03.2011).

Known fire extinguishing solution (patent RU 2510754 C2, A62D 1/00, publ. 04/10/2014) which is prepared in the form of an aqueous solution with a preferred pH = 9.0-9.5 based on a buffer solution containing salts of boric and / or phosphoric acid as well as calcium and / or magnesium carbonate.

Also known are fire extinguishing powder composition based on potassium chloride with additives of zinc oxide, alum-potassium alum, alumina (patent RU 2615715 C1, A62D 1/00, publ. 07.04.2017). Zinc oxide performs a bifunctional action: dusting the composition, which leads to a decrease in caking of the powder, as well as ensuring fluidity due to the release of zinc as a result of chemical transformations between the components of the composite composition.

The closest technical solution is a composition for extinguishing fires (see patent RU 2236880 C1, A62D 1/00, publ. 09/27/2004), the fire extinguishing powder contains alkali and / or alkaline earth metal chlorides as an extinguishing agent, and carbonates are used as a fluidity additive alkaline earth metals, and / or their mixture with graphite and / or nepheline concentrate, or a mixture of graphite with nepheline concentrate, as an anti-caking additive contains hydrophobic silicon dioxide in the ratio, wt. %: anti-caking additive 1.5-4.5; additive for fluidity of 5.0-15.0; extinguishing agent up to 100.

The disadvantage is:

- the complexity of the technological process of grinding components;

- insufficient amount of carbonates in the powder composition necessary to provide a phlegmatizing effect during their thermal decomposition, which reduces the concentration of oxygen in a combustible medium.

The objective of the invention is to increase the fire extinguishing ability of the powder, versatility of use.

The essence of the invention lies in the fact that the fire extinguishing powder composition, including calcium carbonate, silicon dioxide, additionally contains zinc carbonate, aluminum oxide, carbon, in the following ratio of components, mass. %:

calcium carbonate 30-45 zinc carbonate 40-45 aluminum oxide 8-10 silicon dioxide (aerosil) 6-10 carbon in the form of fine colloidal graphite 1-5.

Technical result:

- high fire extinguishing ability;

- ensuring the rupture of the reaction chains in the flame zone, as well as a low level of caking;

- in the combustion zone, the effect of coalescence (the formation of a continuous film on the surface of the burning material) is manifested in the absence of aqueous solutions;

- universality of application, since powders suppress the combustion of materials that cannot be extinguished with water and other substances (for example, metals and some metal-containing compounds);

- high phlegmatizing ability and explosion suppression.

- contributes to the simplification of production technology, since it does not require additional grinding of materials corresponding to the given GOSTs.

The principle of operation of the proposed fire extinguishing powder is that calcium carbonate at high temperature in the presence of graphite as a result of a redox reaction with silicon oxide forms an insoluble calcium silicate that insulates the surface of the combustible material from oxygen access. With an excess of calcium carbonate, free carbon monoxide (IV) is also released, which has a phlegmatizing effect. The resulting calcium oxide also interacts with acidic silicon dioxide (IV) to form a sparingly soluble calcium silicate spreading over the burning surface of solid materials, forming a continuous protective film, reliably isolating the surface from air.

Zinc carbonate behaves similarly to calcium carbonate. At a temperature of 300 ° C it decomposes with the formation of a phlegmatizer - carbon monoxide (IV).

The resulting zinc oxide interacts with silicon oxide (IV), turning into a sparingly soluble zinc silicate

In addition, the decomposition of calcium and zinc carbonates are endothermic reactions, i.e. accompanied by the absorption of a large amount of heat, causing a cooling effect in the combustion zone.

Alumina also performs bifunctional properties. In the presence of alumina in the initial mixture of the components of the extinguishing powder, caking is reduced due to dusting of the composition, and at fire temperature, amphoteric alumina interacts with acidic silicon oxide to form aluminum silicate, which, similarly to calcium and zinc silicates, provides the necessary fluidity in the fire zone.

Characteristics of the starting materials:

Calcium carbonate and zinc carbonate are the main quencher. Their characteristics are given in tables 1 and 2.

Calcium carbonate is a finely ground marble (microcalcite) with physico-chemical characteristics according to GOST R 567 7 5-2015.

Table 1

Physico-mechanical properties and chemical composition of microcalcite GOST R 56775-2015

№№ The name of indicators Value for microcalcite grade KM 200 KM 160 KM-100 one. The largest particle size (d 98), microns 250 185 120 2. The average particle size (d 50), microns fifty 45 thirty 3. The residue after sifting,%, on a sieve with a mesh number 0,080 microns,% St. 1.5 to 2.0 inclusive - - four. The residue after sieving,%, on a sieve with a mesh number 0,063 microns,% - St. 1.5 to 2.0 inclusive - 5. The residue after sieving,%, on a sieve with a mesh number 0,045 microns,% - St. 1.5 to 2.0 inclusive 6. Mass fraction of calcium carbonate, CaCO ₃ , not less than% 98 7. The concentration of hydrogen ions in a 10% aqueous suspension (pH), units 8-10 8. White, conventional units, not less 93 94 94 9. The average density of marble, g / cm ³ 2.6 ± 0.1

Microcalcite is a fire and explosion proof material. By the degree of impact on the human body, it belongs to low-hazard substances and does not form toxic compounds in the presence of other substances or factors in air and wastewater.

table 2

Zinc carbonate performance standards

Characteristics Indicators CAS - number 3486-35-9 Molecular formula ZnCO ₃ Molar mass, g / mol 125.38 Density, g / cm ³ 4.44 Melting point, ° С 300 Solubility in water. g / ml, (15 ° C) 0,001g / 100 ml The residue on the sieve is 75 microns, less,% 6.0

Physico-chemical characteristics of aluminum oxide - alumina (Al ₂ O ₃ ), as well as the characteristics of aerosil (silicon dioxide) are given, respectively, in tables 3 and 4.

Table 4

Characteristics of Aerosil (silicon dioxide) according to GOST 14922-77

OST 6-08-431-75 graphite is used as carbon. Dry colloidal graphite preparations are used as components for the preparation of graphite mixtures and technological lubricants for the manufacture of chemically resistant and anticorrosive coatings, as an additive - a plasticizer during tableting, as components of glue for rubberized fabrics , for the manufacture of contacts and resistors in radio engineering and for other purposes. Graphite is used as part of the extinguishing powder in RF patent No. 2108125 in which potassium chloride is claimed as the main quenching agent. However, this composition is effective in extinguishing class B and D fires, but cannot be used to extinguish class A fires.

Comparative physico-chemical characteristics of the proposed fire extinguishing powder and known according to Patent 2236880 are given in table 5.

The method of preparing a fire extinguishing powder composition is simple, since all components already have the necessary parameters for composing the composite. Powders are mixed in mass ratios.

Claims (2)

A fire extinguishing powder composition comprising calcium carbonate, silicon dioxide, characterized in that it further comprises zinc carbonate, aluminum oxide, carbon in the following ratio, wt.%: calcium carbonate 30-45 zinc carbonate 40-45 aluminum oxide 8-10 silicon dioxide (aerosil) 6-10 carbon in the form of fine colloidal graphite 1-5