RU2075315C1 - Volume fire extinguishing apparatus - Google Patents

Abstract

FIELD: fire extinguishing equipment. SUBSTANCE: apparatus has pyrotechnic charge positioned within heat-insulated casing with intermediate layer of sodium hydrocarbonate. When ignited, pyrotechnical charge burns to produce inhibitors in the form of gaseous compounds and ultradispersed condensed particles, mostly alkali metal salts. During burning of charge, sodium hydrocarbonate is subjected to endothermic decomposition so that additional burning process inhibitors are produced. Cooling cylinder is mounted above casing in annular grooves of band, which has bracket-shaped section. Cooling cylinder has injection space with variable size depending on speed and charge burning temperature. Locking fastening provides for mechanical and geometric closing of joined members. Groove pitch is multiple band width. EFFECT: increased efficiency by providing constant injection space throughout operation period at dynamic transportation loads and enhanced reliability in operation. 4 dwg, 1 tbl

Description

 The invention relates to the field of fire extinguishing, and in particular to devices whose action is based on the use of aerosols as a combustion inhibitor generated during the combustion of a pyrotechnic mixture and released into a protected volume.

 A device for volumetric fire extinguishing, containing a pyrotechnic charge and its ignition unit, is placed in a housing equipped with a nozzle for the exit of gaseous products of combustion into a protected volume, described in the invention according to international application PCT / RU / 00071 of 04/07/92 with priority application SU N 4925423 dated 04/08/91 "A method for producing a fire extinguishing mixture and a device for its implementation", A 62 C 5/02, A 62 D 1/00, international publication number WO 92/17244 of 10.15.92. The pyrotechnic composition (a glycerin-azide polymer with a high nitrogen-containing component or an alkali metal nitrate with a combustible binder) forms an aerosol with high fire extinguishing ability as a mixture of highly dispersed solid particles of combustion inhibitors and neutral gases, which transport them to the fire zone.

 A disadvantage of the known device is the high temperature of the combustion products of the pyrotechnic composition due to the predominant content of a neutral nitrogen atmosphere in the resulting aerosol, which also affects living organisms, which limits the scope for protecting the volumes needed for respiration.

 More perfect is the device according to the invention described in the patent application of the Russian Federation N 5026917 of 02/11/92 "Method of extinguishing a fire and a device for its implementation", A 62 C 3/00, which adopted a positive decision from 08/23/92. In the known device for volumetric fire extinguishing in a thermally protected case, closed by a lid with nozzles and an ignition unit, a pyrotechnic checker is placed, which composition includes salts and hydroxides of alkali metals, metal compounds of alkaline-earth and transition groups with better inhibitory properties.

 The combustion products of the pyrotechnic checkers are emitted in the form of an aerosol mixture, which includes both gaseous compounds and ultrafine particles effective combustion inhibitors. The resulting gas-aerosol mixture is environmentally friendly.

 Additionally, in order to actively mix the combustion products with the surrounding air, a cooling cylinder is mounted axisymmetrically above the casing with a variable injection gap, which is mounted in a predetermined position on the casing by means of a band fastened by a bolted connection.

According to the specified invention, fire extinguishers with the following technical characteristics are commercially available:
weight of pyrotechnic checkers 3.0 kg
specific heat of combustion 3700-3800 kJ / kg
case diameter 165 mm
overall length 485 mm
operating time 90 120 s
maximum protected volume 60 m ³
Practically testing the design of the device made it possible to optimize (by reducing the length of the high-temperature flame) the size of the injection gap for various compositions of the checker:
for low-energy compositions 1.3 5 mm;
for formulations 4.5 using 35 mm energy additives;
for similar, but with a high combustion temperature (≈ 2170 ^o C) compositions of 7.8 50 mm

Moreover, in the cooling cylinder due to active mixing with the injected air from the protected room, the temperature of the aerosol mixture is reduced to 120.160 ^o C, which is noticeably lower than the ignition temperature of organic compounds.

 A disadvantage of the known design is the low functional reliability, which is determined by the following.

 Firstly, due to the fastening of the bandage on the casing by means of a force closure by the sliding friction force, the preservation of the predetermined relative position of the cooling cylinder and the casing (i.e., the injection size) during operation under conditions of shaking, vibration, etc. transport disturbances, for example, in the salons and engine compartments of cars, airliners, railway cars, armored vehicles, boats, etc.

 The case equipped with a checker, as shown by field tests, can move relative to the bandage fixed to the support, changing the injection clearance calculated for this type of pyrotechnic checker and, as a result, the fire fighting efficiency is reduced.

 Secondly, when assembling a fire extinguisher, the installation in each of the given positions of the cooling cylinder is carried out by the operator, which is subjective and does not guarantee the accuracy and reliability of fixing the mount.

 The problem to which the invention is directed, is to increase the functional reliability of the device.

 The required technical result is achieved by the fact that in the known device for volumetric fire extinguishing, containing an aerosol generating flame retardant, a pyrotechnic checker placed in a heat-shielding case, in the cover of which there is an ignition unit and output nozzles equally distributed along the periphery, over which a cooling cylinder is mounted axially symmetrically mounted on the body by means of a bandage, according to the invention, annular grooves are made on the body with a step that is a multiple of the width of the band having in the pope river section shaped staples.

 The implementation of the annular grooves under the brace of the brace on the body is used as the base supports for the brace, fixing the preset position of the cooling cylinder, stiffeners on the inner surface of the body, increasing its structural strength.

 Distinctive features make it possible to accurately set the cooling cylinder in a predetermined position relative to the housing by placing the bandage in the annular grooves necessary for this, which ensures the required injection gap corresponding to the mode of effective functioning of the completed pyrotechnic checker.

 In addition, due to the geometrical closure of the [-shaped bandage in the annular grooves of the housing, the position of the cooling cylinder is reliably fixed for the entire period of operation unchanged under dynamic loads.

 Increasing the stiffness of the casing made it possible to obtain an additional technical result: through the use of direct compression technology of a thermally insulating layer of drinking soda, to obtain a 30% increase in its mass. As a result, the ablative effect of the thermally insulating layer of the body increased and the volume of thermal decomposition products of soda carried away by the flow of hot gases increased, which increases the inhibitory effect and, as a result, decreases the length of the high-temperature flame of the pyrotechnic checkers combustion products.

 Figure 1 shows a General view of the device; in FIG. 2 node I in figure 1, the node of the bandage with a maximum injection gap; figure 3 the same middle position; figure 4 is the same, with a minimum injection gap.

 In the case 1 is placed a pyrotechnic checker 2 of one of the compositions recommended in the table, which are not sensitive to shock, friction, detonation. For the technical implementation of the invention, it is possible to use almost any pyrotechnic compositions, the combustion products of which contain ultrafine condensed particles.

 A layer of sodium bicarbonate 3 with a mass of 1.2 kg weighing relatively cheap and acceptable material for ablative thermal protection of the casing 1 is pressed between the checker 2 and the casing 1. The casing 1 is closed with a cover 4 with a central threaded hole for the ignition unit 5 of the checker 2 and nozzles 6 with a diameter of 12 mm in the amount of 8 pieces.

 Above the nozzles 6, a cooling cylinder 8 is mounted axially to the casing 1 with a necessary injection gap A. By means of the bandage 7. Since the pressure in the casing 1 is limited to 2 atm for safety reasons, the volume of air injected into the cylinder 8 cannot be controlled by the aerosol flow rate.

 By changing the injection gap A, they achieve the most favorable dispersion of the air-aerosol mixture due to thermal diffusion and a sharp decrease in its temperature during forced convective heat transfer because the device operates in the jet pump mode.

 On the housing 1, six annular grooves 9.14 are made with a pitch of 15 mm equal to half the width of the [-shaped section 7 of the bandage.

 The installation of the bandage 7 in the grooves 9 and 11 (FIGS. 1 and 2) provides an injection gap of A 50 mm for the compositions 1.3 of the checker 2. The bandage 7 is rigidly fixed in the grooves by means of a threaded fastening pair 15, forming a lock connection, providing a force and geometric closure of the profile flanging the bandage 7 in the grooves of the housing 1.

 The installation of the bandage 7 in the grooves 10 and 12 (figure 3) provides an injection gap A of 35 mm for the compositions 4 and 5 of the checker 2.

 The installation of the bandage 7 in the grooves 12 and 14 (figure 4) provides an injection gap A of 5 mm for compositions 6.8 of the checker 2.

 In the operating position, the device is mounted by means of the attached bracket 16 in a horizontal position or by a cylinder 8 down.

 The igniter 5 is screwed into the central threaded hole of the cover 4 after installation. Nozzles 6 are closed with plugs 17 for the entire service life before use in operation.

 The device operates as follows. The heat pulse from the ignition unit 5, which is started remotely from the fire alarm system or autonomously (thermochemical, thermomechanical start), triggering when the threshold of the permissible air temperature of the protected room is exceeded, sets fire to the block 2, during combustion of which an aerosol mixture is formed. The composition of the aerosol includes both gaseous compounds of chemical reactions and ultrafine condensed particles having large surface energy as combustion inhibitors.

 With increasing pressure inside the housing 1, the plugs 17 from the nozzles 6 are knocked out by the aerosol stream, which enters the cylinder 8, where it is mixed with the air injected through the gap A. The optimized gap value A provides an intensive supply of aerosol by air flow into the protected volume, preventing the growth and agglomeration of particles, which increases the fire extinguishing efficiency due to the high inhibitory properties of the aerosol.

The hot gases in the housing 1, flowing around the layer 3, endothermally decompose sodium bicarbonate with the formation of CO ₂ and H ₂ O, which are carried away by aerosol, cooling and diluting it. The decomposition products of the thermal barrier layer 3 is an additional combustion inhibitor. The temperature of the housing 1 during the burning of the checker 2 for 90.120 s does not rise above 80 ^o C. The temperature of the extinguishing air-gas mixture at a distance of 1 m from cylinder 8 is 120.160 ^o C, which is safe from the point of view of the occurrence of secondary foci of ignition.

 When an air-aerosol mixture is introduced into the combustion zone, the chain mechanism of the formation of active radicals breaks off due to their recombination, as well as due to their retention on the aerosol surface, each particle of which acts as an energy condenser as a result of the fire being suppressed. High dispersion of active particles, their kinetic nature determine the high fire extinguishing ability of the aerosol formed in the device.

 The installation of the cooling cylinder 8 in a predetermined position is simple and accurate, the fastening of the brace 7 in the annular grooves of the housing 1 is reliable, provides a rigid fixation of the required size of the injection gap A, which is a guarantee of the technological mode of operation of the aerosol generator for the selected type of pyrotechnic checkers 2.

 The device is easy to maintain, reliable in operation, and explosions of vapor and gas mixtures in the volume after extinguishing are prevented.

 The fire extinguishing time, according to the comprehensive laboratory tests, is almost always less than the time of burning the checkers 2.

 Compared with the prototype, the temperature of the housing 1 and the length of the high-temperature zone of the torch of hot gases ejected by the fire extinguisher into the protected room are reduced.

 The device is designed for volumetric fire extinguishing of fires of solid and liquid combustible substances, as well as electrical equipment, including under voltage, as aerosol is a dielectric, chemically neutral and non-toxic.

The device is operable at ambient temperatures from 60 to +55 ^o C and relative humidity up to 100%
The aerosol mixture does not have a harmful effect on clothes and the human body, does not cause damage to property, and there is no decrease in the concentration of oxygen in the air. Aerosol particles are easily removed by wiping, vacuuming or rinsing with water.

 The table shows the pyrotechnic compositions that were tested in the proposed design of an aerosol fire extinguisher under laboratory conditions and at the field testing ground of VNIIGPO Ministry of Internal Affairs of the Russian Federation, protocol N 76 dated 09.03.94. Aerosol generating fire extinguishers according to the claimed invention are recommended for use in protecting storage and utility rooms, workshops, garages, archives and storage, salons and engine compartments of vehicles.

 For the design of the generator for the volumetric aerosol fire extinguishing system, Rostest issued a certificate of conformity N GOST RRI М0 01.4.0138, up to 03.24.96, to which the proposed design fully corresponds.

Claims (1)

 A device for volumetric fire extinguishing, containing a pyrotechnic checker generating an aerosol flame retardant, placed in a heat-shielding case, in the cover of which there is an ignition unit and output nozzles equally distributed along the periphery, over which a cooling cylinder is mounted asymmetrically, mounted on the case by means of a bandage, characterized in that annular grooves are made in the casing with a step that is a multiple of the width of the brace having a cross-section in the shape of a bracket.

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