NZ250328A - Fire fighting unit having aerosol producing solid-fuel charge, adjacent igniter, combustion space and heat absorbing layer with outlet holes - Google Patents

Description

2503 28 1 ■vuy L/cU£(S).,».

! Complete Specification Filed: | Class: (6) ..B.jbac^a/oo Publication Date: 2..7..FEB.. 1996 ; P.O. Journal No: I • .■•-•rr office 3 0 NOV 1994 RECEIVED NEW ZEALAND PATENTS ACT, 1953 No.: Date: COMPLETE SPECIFICATION FIRE-FIGHTING UNIT AND AUTOMATIC FIRE CONTROL SYSTEM > We, LJUBERETSKOE NAUCHNO-PROIZVODSTVENNOE OBIEDINENIE "SOJUZ", of Russian Federation, Moskovskaya oblast, Dzerzhinsky, ulitsa Sovetskaya, 6, Soviet Union hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- (followed by page la) 250328 IO fire-fighting unit and automatic fire control system The present invention relates to fire-fighting equipment and, more particularly, to a fire-fighting unit and an automatic fire-control system.

Widely known in the prior art is a fire-fighting unit in the form of a powder-type fire extinguisher comprising a container with finely-dispersed powder-like extinguishant and a fluid flow generator in the form of a high-pressure cylinder with a check valve, containing either compressed gas or liquid carbon dioxide.

On opening the check valve, the gas or liquid under pressure enters the container with extinguishant forming a fast-moving flow which pulverizes the extinguishant into an air-powder suspension and carries said suspension into the zone of a fire center thus putting out the fire.

The extinguishant in such a fire extinguisher is constituted by powders based on phosphorus-ammonium salts, sodium carbonates and bicarbonates, sodium and potassium chlorides, oxamides, aluminium dioxide, etc.

Depending on the type of powder used the mechanism of fire suppression may vary. Combustion may be quenched by physical or chemical methods, or both. The physical fire-quenching factors include cooling of flames due to expenditure of heat for heating and evaporation of powder particles, and isolation of the center of fire from atmospheric oxygen by creating a separating layer on burning surfaces which denies the access of oxygen.

The fire-extinguishing agents that quench combustion by the physical effect are silica, oxides of copper, barium, magnesium and other inert substances.

The chemical fire-quenching factors include cooling of flames due to expenditures of heat for decomposing the fire-extinguishant, and inhibitation of combustion by merging active centers of chain oxidation reactions taking place on the burning surface.

The fire extinguishants which quench combustion by a chemical factor are potassium or sodium sulfates, potassium chromate, barium nitrate, chlorides of aluminium, potassium, N.? ■ ' :T OiTICE 3 0 NOV 1994 HECEIVF.D 25032S sodium or ammonium, potassium bromide, potassium or sodium carbonates, etc. which act as chemical inhibitors.

The fire-extinguishing powders can be used universally when dealing with burning of various kinds of mechanical and electrical equipment, etc. when water and other means are of no use. Besides, fire-extinguishing powders are of low toxicity or nontoxic altogether and can be used within a broad range of temperatures.

However, fire-extinguishing powders are noted for a high tendency to saturation with water, caking and lumping. Hence, they have a comparatively high fire-suppressing concentration (1.4-1.8 kg/sq m).

Besides, the highest fire-extinguishing effect of these powders is attained at a high fineness of their particles (about 1 micron) which involves certain complications in producing the powder of a requisite fineness and increases its cost. In addition, finely-dispersed powders are highly susceptible to caking.

The conditions for employing the powder-type fire extinguisher may limit the field of its application. Thus, the use of the powder-type extinguisher in transport vehicles is hampered by tough operating conditions, prolonged effect of vibrations, impact loads, dampness, etc.

In addition, the provision in this unit of a high-pressure cylinder and, consequently, of a check valve and connecting pipes renders its design cumbersome and complicated. Further, the difficulties involved in keeping the cylinder pressure-tight within a long period of time fail to ensure highly-reliable fighting of fire and speedy action, all the more so when using the unit on transport vehicles.

Also known in the prior art is a fire-fighting unit (SU, A, 1537279) in the form of a powder-type fire extinguisher with a fluid flow generator conqprising a combustion chamber with the main sol id-fuel charge inside in the form of a cylinder with a through hole. A gas duct located inside said hole is made as a perforated metal pipe one end of which carries one more small solid-fuel charge. An igniter is disposed near said charge. After sending a signal to the igniter, the smaller solid-fuel charge starts burning and the gases flowing through the gas duct into the fire extinguisher body loosen the fire extinguishant preliminarily. After a short time the burning of the smaller solid-fuel charge ignites the main solid-fuel charge so that the main gas flow penetrates the extinguisher body through 3 0 NOV 1994 nLCSIVED 3 250328 perforations in the gas duct and blows the loosened extinguishant into the combustion zone.

This design of the fluid flow generator enables a fast-moving flow of gas to be formed without resorting to the use of high-pressure equipment and permits loosening the fire extinguishant in advance which contributes to the fullest pulverization of the powder. Reliability and fast action of such a fluid flow generator are by far higher than those of the generator in the form of a high-pressure cylirier.

However, the absence in the unit of an efficient system for cooling gases discharged from the gas duct results in caking of extinguishant particles and its premature decomposition under the effect of hot gases escaping from them gas duct which reduces, accordingly, both the physical and chemical fire-suppression effects and tells adversely on the efficiency of the unit.

Besides, said unit has all the above-listed drawbacks inherent in the powder-type fire extinguishers.

Also known is a fire-fighting unit (SU, A, 1475685) in the form of a powder-type extinguisher with a fluid flow generator comprising a body which accommodates a combustion chamber with a solid-fuel charge and an igniter, and a combustion products cooling means in the form of a labyrinth channel formed by three interconnected coaxial chambers. The side surface of the smaller-diameter chamber has tangentially-disposed nozzles while the middle chamber is filled with powdered heat-absorbing substance.

After operation of the igniter, the solid-fuel charge burns up and the hot gaseous combustion products escape at a high speed into the labyrinth channel. The gas moving through the labyrinth channel is partly cooled due to heat exchange with chamber walls. Getting into the chamber of a smaller diameter, the flow of partly-cooled gas is divided into two flows one of which enters the middle chamber containing powder heat-absorbing substance, entrains said substance and rejects part of heat to it while the second flow is twisted by tangentially-arranged nozzles and arrives at the outlet of the middle chamber. The first flow with entrained particles of the powdered heat-absorbing substance also comes here so that further movement of this two-phase flow initiates intensive heat exchange of gas with powder and with chamber walls. Absorbing heat, the powder decomposes and forms gaseous products. Cooled gases enter the powder-type fire extinguisher, 3 0 NOV 1994 | ~£IVED I 250328 " - ^ This design of the fluid flow generator and the provision of a combustion products cooling means produce a flow of cooled gas which pulverizes the powdered fire extinguishant without its caking, lumping and premature decomposition. By liberating gaseous products during decomposition of heat-absorbing powder, this fluid flow generator produces a large amount of gaseous combustion products which carry the powdered fire extinguishant to the site of fire.

However, this generator alone, like all the other above-described generators, cannot be used for extinguishing a fire and must be employed only in combination with a powder-type fire extinguisher so that this unit has all the-above-described disadvantages intrinsic to all powder-type fire extinguishers.

Besides, this design is complicated, cumbersome and utilizes much material since, apart from the fluid flow generator with a large combustion products cooling means, it also comprises a fire extinguisher with fire-extinguishing powder.

Known in the prior art is the use of an aerosol-producing extinguishant (US, A, 3972820) which contains 25-85 wt.-% of haloid compound, 15-45 wt.-% of sodium or potassium chlorate or perchlorate, and 3-50 wt.-% of epoxy resin but there is no information on the use of a fire-extinguishing unit which would use this aerosol-producing fire-extinguishing compound.

For example, if the solid-fuel charge in the unit according to SU No. 1475685 consists of this aerosol-producing compound, the aerosol formed during combustion of said charge and passing through said labyrinth channel will settle on the walls of coaxially-arranged chambers so that the aerosol suspension will disintegrate before it reaches the site of fire.

The process of fire-fighting is automated and the performance of fire-fighting units is improved by automatic fire-control system.

The known automatic fire-control system (JP, B, 6250151) consists of fire-fighting units with their starting initiators, temperature transmitters and a controllable switch. Each temperature transmitter corresponds to at least one fire-fighting unit. The controllable switch comprises two groups of analog switches, a time meter and a multistage comparator of temperature transmitter output signals. The inputs of the first group of analog switches are connected to the outputs of the temperature transmitters, the outputs n.z. fatdnt office 3 0 NOV 1994 RECEIVED 250 of the first group of switches are connected to the inputs of the multistage comparator of temperature transmitter output signals. The. inputs of the second group of analog switches are connected to the outputs of the multistage comparator of temperature transmitter output signals while the outputs of the second group of switches are connected to the starting initiators of the fire-fighting units. The control inputs of both groups of analog switches are connected to the time meter.

At equal time intervals, the time meter sends control signals to the switches for their closing. On closing of switches the signals of temperature transmitters enter the multistage comparator where they are compared with a reference signal. If the temperature transmitter signal exceeds the value of the reference signal, the comparator shapes a control signal delivered to the starting initiator of the corresponding fire-fighting unit.

In case of a fire the signal of the temperature transmitter grows and exceeds the reference signal of the multistage comparator so that a control signal is sent to the starting initiator of the corresponding fire-fighting unit.

Such an automatic fire-control system is sufficiently reliable and puts out the fire without the participation of men.

However this system is complicated so that there is always a chance of its failure. Besides, there is no provision for functioning of the system in case of failure of the temperature transmitter or power supply.

The main object of the invention resides in providing a fire-fighting unit whose design would be adapted for using a compound ensuring three-dimensional fire suppression and would be sufficiently simple, small and safe and in providing an automatic fire-control system which incorporates said unit and which would be highly reliable and capable of functioning in case of failure of the temperature transmitter or of power supply.

This object is attained by providing a fire-fighting unit comprising a body with a combustion chamber containing a sold fuel charge and an igniter disposed near said charge, a combustion products cooling means in the form of a layer of heat-absorbing material and located after the combustion chamber towards the outlet of the discharged combustion products wherein, according to the invention, the solid-fuel charge consists of an aerosol-producing compound, the volume N 7 OFFICE 3 0 NOV 1994 r i / lIVHD 250328 of the combustion chamber exceeds by at least 30 % the volume of the solid-fuel charge contained in the combustion chamber and forms a free space therein at the side of the heat-absorbing layer and wherein the means for the discharge of the combustion products is located after the heat-absorbing layer down the flow of combustion products and has holes communicating with the combustion chamber through passages in the heat-absorbing layer.

To rule out heavy losses of aerosol passing through the heat-absorbing layer and to ensure efficient cooling of the combustion products, it is practicable that the total cross-sectional area of passages in the heat-absorbing layer should vary from 0.25 to 0.7 of the cross-sectional area of the heat-absorbing layer.

To allow for unobstructed discharge of combustion products from the unit, it is preferable that the total area of holes in the combustion products outlet means should be equal to at least 0.25 of the cross-sectional area of the heat-absorbing layer.

To reduce losses of aerosol passing through the combustion products outlet means it is expedient that said means be made in the form of a plate with holes, each being at least 1.5 mm in size.

It is also possible to provide a screen with 1.5-25 mm meshes near the plate.

It is practicable that the sold-fuel charge in the combustion chamber should be separated from the heat-absorbing layer by a spacer.

It is practicable that the spacer should be ring-shaped.

It is expedient that the spacer should have the form of a spring.

It is possible to make the heat - absorbing layer from a friable material with a particle size from 3 to 25 mm in which case the combustion products cooling means should be separated from the combustion chamber by another combustion products outlet means similar to the first one.

It is practicable that the friable material in small units should consist of metal particles.

It is practicable that the friable material in stationary units should consist of natural mineral particles. it is preferable that the natural mineral should be gravel, aluminosilicates or oxides.

To improve the unit performance and minimize its weight it is most preferable that the friable material should consist - rncE- 3 0 NOV 1994 RECEIVED 7 250328 of particles of a polymeric composition containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler.

It is practicable that the polymeric composition should be made of a mixture of plasticized cellulose ether and a component with a high calorific capacity, or a mixture of plasticized synthetic polymer and a component with a high calorific capacity, or a mixture of plasticized cellulose ether and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer and a component with a high endothermic decomposition effect, or a mixture of plasticized cellulose ether, a component with a high calorific capacity and a component with "a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer, a component with a high calorific capacity and a component with a high endothermic decomposition effect.

To improve performance of the unit and reduce its cost, it is preferable that the particles of polymeric composition should have the form of granules or cut tubes 3 to 25 mm in diameter with their length varying from 0.5 to 2.5 of their diameter.

To make a combustion products cooling means which conforms-to all the requirements, it is preferable that the friable material should be a mixture of particles of metal, natural mineral and polymeric composition consisting of at least 5 wt.-% of binder and 60 to 95 wt.-% of filler used in any combinations and ratios.

In order to achieve an additional fire-suppressing effect, it is practicable that a part of friable material should contain particles of aerosol-producing compound weighing 0.1-0.4 of the total mass of the friable material.

In order to improve reliability of fire-fighting unit subjected to prolonged vibration loads, it is preferable that the layer of heat-absorbing material should consist of a plurality of tubes oriented towards outlet of combustion products, extending throughout the length of the layer and forming through passages therein which connect the holes in the combustion products outlet means with the combustion chamber. The cross-section of the passage in each tube should vary from 1.5 to 30 mm and the combustion products cooling means should be separated from the combustion chamber by another combustion products outlet means with holes, similar to the first one.

For the same reason it is still more preferable to make the heat-absorbing layer in the form of a monoblock of a N "> ' • TiCE 3 0 NOV m r.-JJVED 8 solid substance with through passages in the heat-absorbing layer, said passages communicating the holes in the combustion products outlet means with the combustion chamber and having the form of channels in the monoblock with the cross-section of each channel varying from 1.5 to 30 mm.

To raise efficiency of the unit at a minimum weight, it is possible to make a bunch of many tubes or a monoblock of a polymeric composition containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler.

It is practicable in this case that the polymeric composition should consist of a mixture of plasticised cellulose ether and a component with a high calorific capacity, or a mixture of plasticized synthetic polymer and a component with a high calorific capacity, or a mixture of plasticized cellulose ether and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer and a component with a high endothermic decomposition effect, or a mixture of plasticized cellulose ether, a component with a high calorific capacity and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer, a component with a high calorific capacity and a component with a high endothermic decomposition effect.

If the fire-fighting unit is of a large size, it is practicable that the solid-fuel charge be made in the form of at least two separate cartridges.

In order to prevent overheating of the body surface of the fire-fighting unit with hot combustion products, it is practicable that the internal surface of the combustion chamber should be shielded by a spacer of a heat-absorbing agent at least l mm thick.

It is preferable that the heat-absorbing agent should be constituted by a polymeric material.

To raise the efficiency of a fire-fighting unit by creating two flows of aerosol, it is preferable that the solid-fuel charge be disposed in the central part of the combustion chamber and that the second combustion products cooling means and the second combustion products outlet means similar to the first ones should be arranged correspondingly in symmetry therewith.

The object of the invention i's also attained in the automatic fire-control system comprising at least one fire-fighting unit with its starting initiator connected to power supply across a normally-open controllable switch whose control input is connected to the output of the temperature n ?. " ' !.,it:CE 3 0 NOV 1994 RECEIVED 250328 9 _ treuismitter wherein, according to the invention, the fire-fighting unit comprises a solid-fuel charge of an aerosol-producing composition contained in the combustion chamber and a combustion products cooling means, the fire-fighting unit starting initiator has the form of a fuel charge igniter and there is a stand-by power source in the form of a capacitor connected in parallel to the main power source across a protective diode. To keep the system working in case of prolonged power failure, it is practicable that the fire-fighting unit should be provided with a quick-acting blasting fuse connected to the solid-fuel charge.

The disclosed fire-fighting unit, the design "of the combustion products cooling means and the used material of the solid-fuel charge ensure jointly a three-dimensional mechanism of fire-fighting with a complete absence of flames at the unit outlet, Besides, the disclosed unit dispenses with the necessity for additional fire-quenching means in the form of powder or liquid.

The unit is also characterised by single design, small size, high fire-suppressing efficiency and availability of employed materials.

Owing to simplicity of its design, provision of a stand-by power source and the possibility of functioning in case of a long-term power failure, the disclosed automatic fire-control system boasts of a high reliability and safety.

Now the invention will be elucidated by a description of its embodiment with reference to the appended drawings in which, according to the invention: Fig.l is a front view of the fire-fighting unit, vertical section; Fig.2 is a top view of the combustion products outlet means in the form of a plate with a holes and an adjoining screen with mesh, used in the unit shown in Fig.l; Fig.3 is the same as in Fig.l, a version of the unit with a ring-shaped spacer; Fig.4 is the same as in Fig.l, a version of the unit with a spring-like spacer; Fig.5 is the same as in Fig.l, a version of the unit with the heat-absorbing layer constituted by a friable material; Fig.6 is the same as in Fig.l, a version of the unit with the heat-absorbing layer in the form of a bunch of many tubes; Fig.7 is a section along line VII-VII in Fig.6; N.Z. rv ' ■ "' ICE 3 0 NOV TO 0 3 28 Fig.8 is the same as in Fig.l, a version of the unit with the heat-absorbing layer in the form of a monoblock, side view; Fig.9 is a section along line IX-IX in Fig.8; Fig.10 shows the arrangement in the combustion chamber of a solid-fuel charge in the form, of three separate cartridges, sectional top view; Fig. 11 is a version of the unit with a spacer made of heat-absorbing agent, vertical section; Fig.12 is a version of the unit with the second combustion products cooling means and the second combustion products outlet means, vertical section; - ~ Fig. 13 is an elementary electric circuit diagram of the automatic fire control system.

Shown in Fig.l is a fire-fighting unit comprising a body l with a combustion chamber 2, a combustion products cooling means 3, and a combustion products outlet means 4 with holes 5.

The body l is made of any sturdy heat - resistant material, e.g. steel, aluminium or heat-resistant plastic. The shape of the body l can also be of any configuration, e.g. cylindrical, or multi-sided prism with regular polygons in the bases, etc.

The combustion chamber 2 accommodates a solid-fuel charge 6 consisting of any commonly-known aerosol-product ion conqpound. it may be, for example, a mixture of 40-70 wt.-% potassium nitrate, 5-15 wt.-% carbon, the balance being plasticized nitrocellulose, or a mixture of 25-85 wt.-% haloid compound, 15-45 wt.-% sodium or potassium chlorate or perchlorate and 3-50 wt.-% epoxy resin or any other known aerosol-producing compounds.

The volume of the combustion chamber 2 shall be equal to at least l/3 that of the solid-fuel charge 6, the latter being disposed in the chamber 2 so as to form a free space 7.

The free space 7 is required in order to ensure stable burning of the solid-fuel charge 6 of aerosol-producing compound at the initial stage.

If the volume of the free space 7. is smaller than 0.3 of the volume of the solid-fuel charge 6 this will fail to ensure complete combustion of the aerosol-producing, which will reduce the unit efficiency due to a smaller amount of aerosol and increase the amount of toxic agents aldehydes, etc.) in the produced aerosol. 250328 11 The solid-fuel charge 6 is secured in the body l by any conventional method, e.g. by making profiled projections on the walls of said body 1.

Disposed in the combustion chamber 2 near the solid-fuel charge 6 is an igniter 8. It can be located right on the surface of the solid-fuel charge 6 adjoining the free space 7 or in a special hollow made in said charge 6 or else in can be secured to the walls of the body l, etc.

The igniter 8 may be constituted by any conventional electric igniting device, for example a metal spiral filament connected to a DC 10-40-v power source. In order to improve the operational reliability of the igniter *8 and to reduce the supply voltage it is possible to use an additional initiator of coarse-grained black powder disposed near the spiral filament which is in this case connected to a DC 3-12-V power source.

The combustion products cooling means 3 adjoins the side of the combustion chamber where the free space 7 is formed.

The combustion products cooling means 3 has the form of a heat-absorbing layer with through passages 9 for the flow of combustion products.

Located at the outlet from the body l, immediately after the combustion products cooling means 3, is a combustion products outlet means 4 with holes 5 which holds the combustion products cooling means 3 in the body 1 and provides for unobstructed discharge of combustion products from the unit.

The total cross-sectional area of the through passages 9 in the heat-absorbing layer is usually taken to be 0.25-0.7 of the cross-sectional area of the heat-absorbing layer.

If the total cross-sectional area of the through passages 9 in the heat-absorbing layer is less than 0.25 of the cross-sectional area of the heat-absorbing layer, the flow of combustion products becomes intensively turbulized which increases resistance to the movement of the flow through the heat-absorbing layer. This results in heavy losses of aerosol and affects adversely the unit performance.

If the total cross-sectional area of the through passages 9 in the heat-absorbing layer is more than 0.7 of the cross-sectional area of the heat-absorbing layer, this will fail to ensure efficient cooling of combustion products in the means 3.

To provide for unobstructed discharge of combustion products from the unit, the total area of holes 5 of the combustion products outlet means 4 is usually made at least N7 ! ~~nCE 3 0 NOV 1994 .'ED 0 3 28 12 0.25 of the cross-sectional area of the heat-absorbing layer.

This ratio is selected on the basis of the same consideration as those governing the selection of the total cross-sectional area of the through passages 9 in the heat-absorbing layer.

The combustion products outlet means 4 may have the form of a plate with holes 5 as shown in Fig.l or a -combination of a plate with holes 5 and adjoining screen with meshes 10 (Fig.2}. Whatever the form of the means 4, it must- have passages of the size ensuring an unobstructed discharge of combustion products from the unit and reliable fastening of the means 3 in products from the unit and reliable fastening of the means 3 in the body 1.

When the means 4 is made as a plate with holes 5, the size of the passages is determined by the size of the holes 5.

When the means 4 is made as a combination of a plate with holes 5 and an adjoining screen with meshes 10/ the size of the passages is determined by the size of the screen meshes 10.

The size of each passage in the combustion products outlet means 4 in the first embodiment shall be at least 1.5 mm while in the second embodiment it shall vary from 1.5 to 25.0 mm.

If the size of the passages is below 1.5 mm, the latter are apt to get clogged with particles of aerosol which worsens the unit performance substantially.

In some cases it is not advisable to make the size of passages larger than a certain limit, e.g. > 3.0 mm or > 25.0 mm for the reasons which will be dealt with below and which relate to the specific designs of the combustion products cooling means 3.

Consequently, in the first embodiment of the means 4 the size of the plate holes 5 should be at least 1.5 mm. In the second embodiment of the means 4 the size of the holes 5 in the plate shall be at least 1.5 mm while the size of the screen meshes 10 shall vary from 1.5 to 25.0 mm.

The volume of the heat-absorbing layer is habitually 0.3-5.0 of the volume of the solid-fuel charge 6.

If the volume of the heat-absorbing layer is smaller than 0.3 of the volume of solid-fue£. charge 6 this fails to provide for sufficient temperature reduction of the combustion products. In this case the flames produced during 250328 13 limits of the unit and set fire to the nearby combustible objects.

If the volume of the heat-absorbing layer is greater than 5.0 of the volume of the solid-fuel charge 6, the aerosol passing through the heat-absorbing layer will settle in it thus reducing the unit efficiency.

To separate the solid -fuel charge S from the heat-absorbing layer , the combustion chamber 2 may be provided with a spacer in the form of a ring 11 (Pig. 3) or a spring 12 (Fig.4).

The heat-absorbing layer may consist of a friable material (Fig.5) , with the size of its particles 13 ranging from 3 to 25 mm.

In this case the combustion products cooling means 3 may be separated from the combustion chamber 2 by another combustion products outlet means 14 with holes 5, 10 similar to the first one and performing the same functions.

The means 14 can also be made in the form of a plate with holes 5 or in the form of a aconibi nation of a plate with holes 5 and an adjoining screen with meshes 10.

The total area and size of passages in the means 14 are selected on the basis of the same considerations as for the first means 4, i.e. the dimensions of the passages shall provide for unobstructed discharge of combustion products from the unit and reliable fastening of the means 3 in the body l.

It becomes clear that the maximum size of passages in the means 4 and 14, when the heat-absorbing layer is constituted by a friable material with the size of particles 13 equalling, for example, 3 or 25 mm, shall not exceed, respectively, 3 mm or 25 mm otherwise the particles 13 of the heat-absorbing material may fall through the passages in the means 4 and 14 or be entrained from the unit by the flow of combustion products.

The through passages 9 in the layer of friable heat-absorbing agent are formed due to a loose contact among the particles 13.

If the particles 13 are smaller than 3 mm, the total cross-sectional area of the through passages 9 in the heat-absorbing layer will be less than 0.25 of the cross-sectional area of said layer so that an overly compact packing of particles 13 will interfere with the disch;»«"10 of aerosol 14 250328 If the particles 13 sure larger than 25 mm, the total cross-sectional area of the through passages 9 in the heat-absorbing layer will be greater than 0.7 of the cross-sectional area of said layer. Therefore, there will be no efficient cooling of combustion products in the means 3 so that flames may escape out of the unit.

The friable material may be constituted by metal particles. Usually it is production waste such as metal chips or disintegrated metal scrap. Inasmuch as metal particles feature a high calorific capacity and, consequently, a high heat-absorptivity, they are^- very convenient for use. However, when metal particles are used in large fire-fighting units, a high specific weight of these particles and a high temperature of combustion products may lead to baking of said particles. Therefore, it is expedient that such chips be used in small-size units, for example, the ones used to protect small rooms.

•Besides, the friable agent may be constituted by particles of natural minerals. Like metal particles, the mineral particles have a sufficiently high calorific capacity but under vibration loads they may be abraded and diminish considerably in size. Therefore, the fire-fighting units with the heat-absorbing layer consisting of natural minerals are, as a rule, used in stationary conditions.

The natural minerals are gravel, aluminosilicates, oxides, etc.

The metal particles of industrial waste and the natural minerals, e.g. gravel, are also used to reduce the cost of the unit.

The efficiency of the unit is improved and its weight is minimized by using the friable material consisting of particles of a polymeric composition containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler. The binder usually consists of plasticized cellulose ether (nitrocellulose, acetyl cellulose, ethyl cellulose, etc.) or plasticized synthetic polymer. The filler is made from a component with a high calorific capacity (metals, oxides, natural minerals, etc.) and/or a component with a high endothermic decomposition effect (oxamides, oxalates, carbonates of metals, etc.).

The ratio of components in a composition is selected to suit the operational requirements of the unit.

For example, if a fire-fighting unit is intended for use in transport vehicles and is expected to suffer a prolonged effect of vibrations and sharp temperature variations, the N.7 ' "ICE 3 0 NOV 1994 hi_ i v'LD 250328 ~ • heat-absorbing material shall satisfy high strength requirements. A high mechanical strength is ensured by a high content of binder (25-40 %) . In this case the content of the filler (cooling component) is correspondingly reduced which cuts down the efficiency of the combustion products cooling means.

If the fire-fighting unit is used under stationary conditions, e.g. to protect hangars, garages, and the like, the content of the filler may be at a maximum (80-95 %) while that of the binder, at a minimum (5-20 %).

The use of polymeric compositions whose filler decomposes at a relatively low temperature (160-200 C) and has a high endothermic effect is more efficient than the use of an indecomposable component with a high calorific capacity because in the case of a component with a high endothermic decomposition effect the combustion products are cooled under the action of two factors: physical, due to expenditures of heat for heating polymeric composition particles; and chemical, due to heat expenditures for decomposition of this component.

For this reason, in spite of a higher cost of the unit, using the filler with a high endothermic decomposition effect is deemed preferable.

Sometimes, a need arises in using a filler whose component with a high calorific capacity is combined with a component having a high endothermic decomposition effect.

To raise efficiency of the unit and cut down its cost, the particles of polymeric composition are made in the form of granules or cut tubes.

The point is that , firstly, the granules and cut tubes are a semifinished product used for making various articles from polymeric compositions. The procurement of this product poses no technical problems and reduces considerably the cost of the unit.

Secondly, the granules have a large external surface and ensure the passage of a maximum amount of aerosol through the heat-absorbing layer at a maximum contact with the surface of its particles thus ensuring a high degree of aerosol cooling. The cut tubes have a still more developed surface which further increases the aerosol cooling effect.

The optimum effect is attained by using granules and cut tubes 3 to 25 mm in diameter with a length 0.5 to 2.5 times their diameter.

However, the granules and cut tubes are abraded under the effect of long-term vibration loads, their size is N-Z- !:>/T rrHCE 3 0 NOV 1994 KL . :vLD 16 *503*# diminished and structure violated. In this case they are ultimately compacted which may bring about heavy losses of aerosol.

The friable material may be mixed from particles of metal, natural mineral, and polymeric composition and contain at least 5 wt.-% of binder and 60 to 95 wt.-% of filler used in various combinations and ratios.

Thus, it becomes possible to make the combustion products cooling means 3 which has any required characteristics,' i.e. low cost, light weight, high strength, vibration and heat resistance, etc.

To achieve an additional fire-fighting effect, part of the friable material in the combustion products cooling means 3 may contain particles of an aerosol-producing compound. The particle size of this compound is selected between 3 and 35 mm on the ground of the above-stated considerations. The additional fire-fighting effect is achieved in this case due to decomposition of the particles of aerosol-producing compound when hot fire-fighting aerosol passes through the combustion products cooling means 3 thus producing an additional amount of aerosol.

The mass of particles of aerosol-producing compound in the friable material usually accounts for 0.1-0.4 of the total mass of the friable material.

If the mass of said particles is less than 0,1 of the total mass of the friable material, the additional fire-fighting effect is insignificant.

If the mass of said particles is greater than 0.4 of the total mass of the friable material, the effect of cooling the combustion is weakened and the unit itself may present a cause of fire.

The heat-absorbing layer may have the form of a bunch of many tubes 15 (Fig.6, 7) oriented towards the discharge of combustion products and extending throughout the length of the layer. The through passages 16 in the heat-absorbing layer are formed in this case by holes in the tubes 15 and the spaces between them.

The area through the passages 16 in the tubes 15 (i.e. their inside diameter), as well as the outside diameter of the tubes 15 shall answer the following condition: the total cross-sectional area of the through passages in the heat-absorbing layer shall be 0.25-0.7 of the cross-sectional area of the heat-absorbing layer.

The actual size and number of tubes 15 depend on the size of the fire-fighting unit. For the above-stated reasons it N.Z. pAT' ' ' ~ TfQE 3 0 NOV 1994 Rf 250328 will be understood that the inside diameter of the tubes shall be not under 1.5 mm.

The cross-sectional area through each tube 15 larger than 30 mm is impracticable since it will not ensure efficient cooling of the combustion products.

For example, in the fire-fighting unit with an inside diameter of 69 mm the optimum solution is to make the heat-absorbing layer in the form of a bunch of 85 tubes with outside and inside diameters of 6,5 and 2,5 mm, respectively, instialled along the unit axis. In this case, the free passage area through said bunch of tubes is approximately 0.3 of the cross-sectional area of the heat-absorbing layer.

To secure the bunch of tubes 15, the combustion products cooling means 3 is separated from the combustion chamber 2 by the second combustion products outlet means 14 with holes 5, 10, similar to the first one. It is evident that the means 14 in this case is made as a combination of a plate with holes 5 and an adjoining net with meshes 10 which ensures reliable fastening of the meanr 3 and unobstructed discharge of aerosol from the unit.

Making the means 3 in the form of bunch of tubes 15 guarantees its strength under the effect of prolonged vibration loads.

A disadvantage of this design lies in a great amount of labour involved in fitting the tubes 15 into the unit body l.

Still stronger and more resistant to prolonged vibration loads is the design wherein the means 3 has the form of a monoblock 17 (Pig.8,9) made of a solid material. In this case, the through passages 18 in the heat-absorbing layer connecting the holes of the means 4 with the combustion chamber 2 are made in the form of channels in the monoblock 17. The passage area through each of said channel is selected by the same method as the size of the passages 9, 10 in the means 3 when the latter is made of friable material 13 or as a bunch of tubes 15.

When the fire-fighting unit with the means 3 in the form of the monoblock 17 is used under stationary conditions, there is no purpose in installing the means 14 between the combustion chamber 2 and the means 3 since in this case there is no need in additional fastening of the latter.

Usually, the monoblock 17 and the tubes 15 are made from a polymeric composition containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler.

N.z. r/ 3 0 NOV 1994 250328 18 ~ The content of components in the composition is selected on the ground of the same consideration as those governing the content of the heat-absorbing layer constituted by friable material 13 consisting of polymeric composition particles.

A disadvantage of the means 3 having the form of monoblock 17 lies in that, in case of a high content (80-95%) of filler and a low content (5-20%) of binder, the composition features poor technological properties and is difficult for mold the monoblock 17 with through holes.

The use of fire-fighting units with the means 3- -in the form of a bunch of tubes 15 or monoblock 17 is practically unlimited.

In large-size fire-fighting units the production of the solid-fuel charge 6 can be simplified by making it in the form of several separate cartridges 19 (Pig.10).

In order to prevent overheating of the surface of the unit body 1 with hot products of combustion, the internal surface of the combustion chamber 7 (Fig.il) in some cases is shielded by a spacer 20 made from a heat-absorbing material at least l mm thick.

The heat-absorbing material of spacer 20 can be made , for example, of asbestos or fiberglass.

Besides, the heat-absorbing material of the spacer 20 can be made from a composition identical with the heat-absorbing material of the combustion products cooling means 3.

For example, the spacer 20 may be rolled from a material with a component having a high endothermic decomposition effect.

Additional insulation of the unit body 1 prevents the possibility of secondary ignition of combustible gases and flammable liquids which in particularly important in protection of engine compartments of transport vehicles.

The heat-insulating spacer 20 thinner than 1 mm fails to provide efficient shielding of the walls of the body 1.

To promote efficiency of the fire-fighting unit by the possibility of creating two streams of aerosols, the solid-fuel charge 6 (Fig. 12) can be disposed in the central part of the combustion chamber 2 creating two free spaces 7, 21 therein on either side of the solid-fuel charge 6.

In this case the unit has a second combustion products cooling means 22 and a second combustion products outlet means 23, both being similar to the first ones and arranged symmetrically therewith.

NX "n,ciE_ 3 0 NOV 1994 HL.OL.1 V v-lJ 250328 19 Shown in Fig. 13 is an elementary electric circuit diagram of the automatic fire control system according to the invention.

The system comprises at least one above-described fire-fighting unit 24 (a plurality of such units in the described embodiment) comprising a solid-fuel charge 6 from an aerosol-production compound located in the combustion chamber 2, a combustion products cooling means 3, a combustion products outlet means 4, and an igniter 8 of the solid-fuel charge.

The fire-fighi-ing units 24 are installed in the most'fire-hazardous points of the protected location. Their number in the system depends on the volume of the protected object, on the design and size of the fire-fighting units 24.

The number of the fire-fighting units 24 in the system required to protect a specific object is calculated by the formula m CVKtKl n = = . (d ml ml where m - required mass of aerosol-producing compound, g; ml- mass of aerosol-producing compound in one fire-fighting unit , g; C - fire-suppressing concentration of aerosol, g/cu m; V - protected volume, cu m; K - number of air changes in protected volume, cu m/s; t - operating time of fire-fighting unit,s; Kl - safety factor for aerosol losses in unit.

In case of several fire-fighting units 24, they are connected to power supply 25 in parallel.

The igniters 8 of the fire-fighting units 24 are connected to power supply 25 across at least one controllable switch 26.

Power supply 25 is usually constituted by a 3-40 V DC source.

The controllable switch 26 may be any microswitch with a control input. The controllable switches 26 connected in parallel with one another are normally open and so is the electric supply circuit of the igniters 8 of the fire-fighting units 24. If at least one controllable switch 26 250328 - closes, the electric circuit of the igniters 8 closes too. The control input 27 of each controllable switch 26 is connected to the output 29 of the corresponding temperature transmitter 28. Said transmitters 28 are installed in the most fire-hazardous points. Their number in the system depends on the volume of the protected object. Two manual system-starting buttons 30 are cut into the circuit of the power source 25 in series with each other and parallel with the controllable switches 24 which means that all the fire-fighting units 24 are operated either by pressing both manual system-starting buttons 30 or by sending acpntrol signal from the output 29 of the temperature transmitter 28 to at least one controllable switch 26.

The temperature transmitter 29 may be constituted by any transmitter with a sluggishness up to l s producing a continuous output signal proportional to the ambient temperature or a transmitter operating when a certain temperature is exceeded.

The system incorporates a stand-by power source in the form of a capacitor 31 connected parallel with the main power source 25 across a protective diode 32. When the main power source 25 is ON, the capacitor 31 is charged to the voltage of said source 25. The protective diode 32 prevents discharge of the capacitor 31 in case of failure of the main power source 25. The provision of the capacitor 31 and protective diode 32 keeps the system operative for about 30 min after failure of the main power source 25.

To ensure operation of the system in case of a prolonged supply failure, there is a quick-acting safety fuse 33 connected directly to the solid-fuel charge 6.

The quick-acting safety fuse 33 usually has a linear speed of thermal pulse transmission from 80 to 300 mm/s. It may be made, for example, on the basis of nitrocellulose plasticized with azidoplasticizer, etc. The fuse 33 is positioned in the most fire-hazardous point.

The fire-fighting unit shown on Figs. 1-12 according to the invention, functions as follows.

In case of a fire, a power source in the protected room or compartment is turned ON and a DC electric pulse is delivered to the igniter 8 which ignites the solid-fuel charge 6. The burning charge 6 produces hot gaseous and finely dispersed (about l micron) condensed products of combustion which possess fire-inhibiting properties and form an aerosol (suspension of condensed combustion products in gas) . This aerosol is a fire extinguishant. Burning of the n.z. p/'otmt office 3 0 NOV 1994 250328 solid-fuel charge 6 builds up excess pressure in the combustion chamber 2 and aerosol moves through the passages 9 of the combustion products cooling me cms 3 where it is cooled. The cooled aerosol moves from the fire-fighting unit through the holes 5, 10 of the combustion products outlet means 4, fills the protected room or compartment and suppresses the chain reactions of combustion thus realizing the three-dimensional mechanism of fire control.

The system functions as follows.

In case of fire in the protected room or compartment, a control signal that exceeds the signal for operation of the controllable switch 26 moves from the output 29 of at* least one temperature transmitter 28 to the control input 27 of said switch 26. The controllable switch 26 closes the electric supply circuit of the igniters 8 of the fire-fighting units 24 thus setting them in operation.

If the main supply source 25 becomes broken or deenergized, the voltage in the system is maintained for about 30 min by the capacitor 31.

If all the temperature transmitters 28 have failed, the system can be started manually by pressing both manual start-up buttons 3.

If power supply is cut off for a long time or the temperature transmitters 28 fail to operate, the system will be started due to direct contact of flames with the safety fuse 33 which will be ignited.

In this case, the igniter 8 is not required since the solid-fuel charge 6 of the fire-fighting unit 24 is ignited directly by the safety fuse 33.

High efficiency of the disclosed automatic fire control system has been confirmed by tests performed in quenching a fire on the burning engine of a cargo truck.

Example l The automatic fire-control system was installed in the engine compartment of a cargo truck. The compartment volume was 0.5 cu m. The selected design of the fire-fighting unit had a steel cylindrical body of 52 mm inside diameter, 80 mm high. The diameter of the solid-fuel charge was 48 mm. The mass of the aerosol-producing compound was 60 g. The burning time of the aerosol-producing compound was 8 s. The combustion products cooling means consisted of a friable material (gravel) with an average particle size of 10 mm. The spacer had the form of a ring 22 mm high. The combustion 3 0 NOV 1994 ntCEIVED 250328 22 ^ products outlet means arranged on either side of the combustion products cooling means had the shape of the plates 1.5 mm thick with 4-mm dia holes. Each plate had 35 holes.

The fire-suppressing concentration of aerosol was determined experimentally by conventional methods on the condition that fire would be extinguished within 5 s. Concentration was 30 g/cu m. The number of air exchanges in the engine compartment was found experimentally and was 0.86 cu m/s. The safety factor for aerosol losses in the unit and leaks in the engine compartment was 2.

The number of fire-fighting units required to protect the engine compartment was found by formula (l) : CVKTKl 30*0.5*0.86*8*2* 206.4 n = = + = 3.44 ml 60 60 which means that four fire-fighting units were required. Hence, four units were positioned in various points of the truck engine compartment. The experiments determined their optimum location which permitted distributing the turbulent flow of aerosol uniformly over the entire volume of the engine compartment within a minimum time.

There was one temperature transmitter with shape memory, incorporating a microswitch in its body. Power supply was from 12 V automotive storage battery.

The engine was poured over with gasoline. For additional centers of fire , several cans with gasoline were placed in various points of the engine compartment. The total amount of gasoline was 400 ml. Truck movement was simulated by delivering compressed air (pressure 1.5 atm. total consumption 5 cu m) from a compressor into the truck radiator.

Gasoline was set on fire. When gasoline was flamed up the engine hood was closed. The flames operated the transmitter temperature, the electric circuit was closed and voltage was delivered from the supply source to the igniters which ignited the solid-fuel charges in, the fire-fighting units. Upon closing the hood it was possible to observe light and flame tongues through the radiator blind. When the pieces of aerosol-producing extinguishant were ignited, the compartment under the hood was filled with large amount of compact white smoke i.e. aerosol which escaped through the 3 0 NOV 1994 h-v". LIVED

Claims (29)

23 250328 blind. The compound was burning for eight seconds but the fire centers in the engine compartment within 3-5 s. after the start-up of the fire control system. On opening the hood and inspecting the engine, the nonburnt gasoline was found to remain in the cans. Example 2 The test conditions were the same as in Example 1. The fire-fighting units were set in operation ~by the manual start buttons from the driver's cab. The results were the same as in Example l. WHATJTWE CLAIM IS: Claimo

1. A fire-fighting unit comprising a body (l) accomodating a combustion chamber (2) and a solid-fuel charge (6) and igniter (8) located near the solid-fuel charge (6), a combustion products cooling means (3) in the form of a layer of heat-absorbing agent disposed after the combustion chamber (2) towards an outlet of the unit CHARACTERIZED in that the solid-fuel charge (6) consists of an aerosol-producing compound, the volume of the combustion chamber (2) is at least 30 % larger than that of the solid-fuel charge (6) which forms a free space (7) with an adjacent side of the heat-absorbing layer, a combustion products outlet means (4) is located after the heat-absorbing layer down the flow of the combustion products and has holes (5) which communicate with the combustion chamber through passages (9) in the heat-absorbing layer.

2. A unit according to Claim l CHARACTERIZED in that the total cross-sectional area of the through passages (9) in the heat-absorbing layer is 0.25-0.7 of the cross-sectional area of the heat absorbing layer.

3. A unit according to Claim 2 CHARACTERIZED in that the total area of holes (5) in the combustion products outlet means (4) is at least, 0.25 of the cross-sectional area of the heat-absorbing layer.

4. A unit according to Claim 3 CHARACTERIZED in that the combustion products outlet means (4) has the form of a platf^ with holes (5) each at least 1.5 mm in diameter . 250328 24

5. A unit according to Claim 4 CHARACTERIZED in that located near the plate is a mesh screen with apertures (1) varying in size from 1.5 to 25.0 mm.

6. A unit according to Claim 1 CHARACTERIZED in that the combustion chamber (2) houses a spacer for separation in space of the solid-fuel charge (6) and the heat-absorbing layer.

7. A unit according to Claim 6 CHARACTERIZED in that the spacer has the form of a ring (n).

8. A unit according to Claim 6 CHARACTERIZED in that the spacer has the form of a spring (12).

9. A unit according to Claim 5 characterized in that the heat-absorbing layer consists of a friable material with the size of particles (13) varying from 3 to 25 mm, the combustion products cooling means (3) being separated from the combustion chamber (2) by a second combustion products outlet means (14) similar to the first one.

10. A unit according to Claim 9 CHARACTERIZED in that the friable material is constituted by metal particles.

11. A unit according to Claim 9 CHARACTERIZED in that the friable material is constituted by particles of natural mineral.

12. A unit according to Claim 11 CHARACTERIZED in that the natural mineral is gravel, aluminosilicates or oxides.

13. A unit according to Claim 9 CHARACTERIZED in that the friable material is constituted by particles of a polymeric composition containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler.

14. A unit according to Claim 13 CHARACTERIZED in that the polymeric composition is a mixture of plasicized cellulose ether and a component with a high calorific capacity, or a mixture of plasticized synthetic polymer and a component with a high calorific capacity, or a mixture of plasticized cellulose ether and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer and a component with a high endothermic effect, or a mixture of plasticized cellulose ether, a component with a high calorific capacity and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer, a- component with a high calorific capacity and a component with a high endothermic decomposition effect.

15. A unit according to Claim 14 CHARACTERIZED in that tha^— -^ particles of the polymeric composition have the f oritu^f r r'c 25 0 3 28 25 granules or cut tubes 3 to 25 mm in diameter, the length of granules or cut tubes being 0.5 to 2.5 their diameter.

16. A unit according to Claim 9 CHARACTERIZED in that the friable material is constituted by a mixture of metallic, natural mineral and polymeric composition particles containing at least 5 wt.-% of binder and 60 to 95 wt.-% of filler used in any combinations and ratios.

17. A unit according to Claim 9 CHARACTERIZED in that the part of friable material contains particles of aerosol-producing compound whose mass is 0.1 to 0.4 of the total mass of the friable material.

18. A unit according to Claim 5 CHARACTERIZED in that the layer of heat-absorbing material has the form of a bunch' of tubes (15) oriented towards the combustion products outlet end, extending throughout the length of the layer and forming through passages (16) therein which communicate the holes (5, 10) of the combustion products outlet means (4) with the combustion chamber (2), the cross-sectional area (16) of each tube (15) being 1.5-30 mm2 and the combustion products cooling means (3) being separated from the combustion chamber (2) by the second combustion products outlet means (14) similar to the first one and having holes (5, 10).

19. A unit according to Claim 4 CHARACTERIZED in that the heat-absorbing layer has the form of a monoblock (17) made from a solid material, having through passages (18) which communicate holes (5) of the combustion products outlet means (4) with the combustion chamber (2) and made in the form of channels in the monoblock, the cross-sectional area of each channel varying from 1.5 to 30 nun^.

20. A unit according to Claims 18 or 19 CHARACTERIZED in that the heat-absorbing layer is made of a polymeric composition at least 5 wt.-% of binder and 60 to 95 wt.-% of filler.

21. A unit according to Claim 20 CHARACTERIZED in that the polymeric composition consists of a mixture of plasticized cellulose ether and a component with a high calorific capacity, or a mixture of plasticized synthetic polymer and a component with a high calorific capacity, or a mixture of plasticized cellulose ether and a component with a high endothermic decomposition effect, or a mixture of plasticized synthetic polymer and a component with a high endothermic decomposition effect, or a mixture of plasticized cellulose ether, a component with a hig^^;";~^ calorif ic capacity and a component with a high endothermicv 250328 decomposition effect, or a mixture of plasticized synthetic polymer, a component with a high calorific capacity and a component with a high endothermic decomposition effect.

22. A unit according to Claim l CHARACTERIZED in that the solid-fuel charge (6) has the form of at least two separate cartridges (19).

• 23. A unit according to Claim 1 CHARACTERIZESD in that the internal surface of the combustion chamber (2) is shielded by a spacer (20) of a heat-absorbing agent at least l mm thick.

24. A unit according to Claim 23 CHARACTERIZED in th^t the heat-absorbing agent is constituted by a polymeric material.

25. A unit according to Claim 1 CHARACTERIZED in that the. solid-fuel charge (6) is accommodated in the central part of the combustion chamber (2) and forms free spaces (7,21) therein on either side of the solid-fuel charge (6) and in that the unit has a second combustion products cooling means (22) and a second combustion products outlet means (23) similar to the first ones and arranged symmetrically therewith.

26. An automatic fire-control system comprising at least one fire-fighting unit (24) according to Claim 1 with its ignitor connected to the power source (25) across a normally-open switch (26) whose control input (27) is connected to an output (29) of a temperature transmitter (28) CHARACTERIZED in that the fire-fighting unit (24) comprises a solid-fuel charge (6) of an aerosol- producing compound located in a combustion chamber (2) and a combustion products cooling means (3), ; 1— and in that there is a stand-by power source in the form of a capacitor (31) connected in parallel to a basic source (25) across a protective diode (32) .

27. A system according to Claim 25 CHARACTERIZED in that the fire-fighting unit (24) has a quick-acting safety fuse (33) connected to the solid-fuel charge (6). 27 250328

28. A fire fighting unit according to claim 1 when constructed, arranged and operable substantially as herein described with reference to any example thereof and the accompanying drawings.

29. An automatic fire control system according to claim 26 when constructed, arranged and operable substantially as herein described with reference to any example thereof and the accompanying drawings. dated this op fjoemte A. J. PARK & SON PER: AGENTS FOR THE APPLICANTS n.z. fv" 3 0 NOV TO