FIRE EXTINGUISHING APPARATUS

Abstract: There is described fire extinguishing apparatus comprising: a storage reservoir for the storage of fire extinguishing medium; an atomisation device comprising an atomiser head provided with at least one nozzle for the passage of fire extinguishing medium from the storage reservoir to the exterior of the apparatus and a valve for controlling the passage of fire extinguishing medium from the storage reservoir to the atomiser head; pressure generating means capable of applying pressure to liquid stored in the storage reservoir; and charge generating means capable of applying charge to the fire extinguishing medium, the arrangement being such that upon actuation of the apparatus fire extinguishing medium stored in the storage reservoir is forced out of the apparatus in charged, atomised form.

Description: FIRE EXTINGUISHING APPARATUS The present invention relates to fire extinguishing apparatus and in particular to automatic fire extinguishing apparatus which uses a liquid as the extinguishing medium. In hotels, office premises and public buildings it is common to use a fire extinguishing system by which water is distributed to strategic sprinkler points by pipes connected to a stored reservoir, e.g. a local storage tank. At each strategic sprinkler point, there is placed a sprinkler device comprising a valve and a sprinkler head. When a valve is actuated at a sprinkler point, water from the stored reservoir is allowed to issue from the sprinkler device so as to douse any conflagration in the area of the sprinkler point. In order to make the system automatic, it is common for the sprinkler head to incorporate a capsule of a liquid which has a high coefficient of expansion, such as Toluol. When the liquid is warmed by the heat of a local fire, the capsule is fractured by the pressure of the expansion and this allows a water valve to open. Although such systems are usually effective in extinguishing a local conflagration, there are several disadvantages :- 1. It will be appreciated that once the valve is opened, the water continues to issue from the sprinkler head until it is turned off (by the action of fireman or other official attending the scene) or until the stored reservoir of water is exhausted. It is therefore a common occurrence that far more water is used than that which is actually necessary to extinguish the flames. It is common knowledge that the damage caused by water extinguishing systems is often very much greater than that caused by any fires which they extinguish. 2. It will also be understood that the use of a dousing water extinguishant cannot be permitted where electrical apparatus is in use nearby. Liquid water is a conductor of electricity and the connection of a wet surface to an electrical system is dangerous to persons who approach the area. 3. The use of a water dousing extinguishant in high-rise buildings brings with it many extra costs which are not easily accepted. It is necessary to store the water at the top of the building so that it is available for use under fire conditions - when it must be assumed that all electrical power has been disconnected (i.e. no pumping systems are operational). The extra structural strength which has to be incorporated into the building to take the deadload of the water tank increases the cost of the building. Further, it will be understood that the extinguishing of a fire on. for example, the 20th floor will cause damage to several lower floors from the water saturation of the walls, floors and ceilings. 4. It will also be obvious that the use of a piped water dousing extinguisher system is unacceptable in many small hotel premises because of its cost. It is clearly out of the question for most private homes. Because of the disadvantages listed above, several other types of fire extinguishing systems have been devised, of which the halon gas saturation and water fog devices are examples. It has been common practice to use a system which releases halon gas under pressure to displace the air in places such as computer rooms or the engine compartments of ships and military vehicles. Gaseous halon compounds have the useful property of endothermic dissociation - that is to say they can absorb energy from a flame, cooling it whilst generating byproducts that suppress combustion. Halons are therefore extremely effective as extinguishants and there are no problems with electrical equipment close to the fire. Unfortunately the halons and their byproducts are known to be dangerous to human life and it is normal to arrange for a short period of alarm to allow evacuation before releasing halon gas into areas in which human beings may be present. Further, halons are analogues of CFCs of the type held to be harmful to the ozone layer and their manufacture and use is now strongly discouraged. In recent years high-pressure water fog systems have been tested in high-value areas for which a halon gas would have been chosen previously. Water fog systems use atomiser heads in place of the sprinkler heads used by conventional water dousing arrangements. The water is supplied at very high pressure (40 bar), which causes the water to issue from the atomiser heads as a dense fog and not as a deluge of liquid. The operating principle of a water fog device is not to soak the flammable material generally but to absorb the energy of the flame itself, in the same way that the endothermic dissociation of a halon gas does. The concept has been proved to be remarkably effective, to require the use of only very small quantities of water and to be safe in the vicinity of electrical equipment. Unfortunately, the water fog equipment now on the market has to use piping systems, valves and reservoirs that can withstand the high pressures required. which make the systems expensive to install There are also obvious safety problems Like halon systems, water fog units of this type cannot be seriously contemplated for use in public buildings or domestic premises It is an object of this invention to construct an efficient, automatic, modular fire- extinguishing apparatus that uses the water fog principle but which avoids the principal disadvantages of previous equipment According to the present invention there is provided apparatus for use as a fire extinguishing or security device which apparatus comprises a storage reservoir capable of the storage of a fire extinguishing medium, an atomisation device comprising an atomiser head provided with at least one nozzle for the passage of fire extinguishing medium from the storage reservoir to the exterior of the apparatus and a valve for controlling the passage of fire extinguishing medium from the storage reservior to the atomiser head, pressure generating means capable of applying pressure to fire extinguishing medium stored in the storage reservoir, and charge generating means capable of applying charge to the fire extinguishing medium, the arrangement being such that upon actuation of the apparatus fire extinguishing medium contained in the storage reservoir forced out of the apparatus in a charged, atomised form The charge generating means should be situated within the apparatus so that it can apply the required charge to fluid extinguishing medium prior to its exit from the apparatus. The charge generating means may be situated between the storage reservoir and the external surface of the atomisation device. The charge generating means is preferably capable of applying a charge to, i.e. of ionisation of, individual droplets of atomised fire extinguishing medium. The charge generating means may take the form of an electrostatic charge generator and charge may be applied to the fire extinguishing means by its passage between a pair of suitably positioned electrodes, preferably separated by an electrical insulator. The charge generating means preferably applies a negative charge to the fire extinguishing medium. The charge generating means may be automatically and/or manually activatable. Preferably the charge generating means is automatically activated, for example, upon detection by the apparatus of a triggering external stimuli, or when the valve of the atomising device allows passage of fire extinguishing medium from the storage reservoir to the atomiser head or upon arrival of fire extinguishing medium at the atomiser head. The pressure generating means has the function of forcing fire extinguishing medium out of the storage reservoir. The pressure generated by the pressure generating means is preferably of the order of at least one hundred psi. The pressure generating means is more preferably capable of producing a pressure of at least two hundred and more preferably three hundred psi to the surface of fire extinguishing medium contained in the storage vessel. The pressure generating means is preferably capable of applying the generated pressure to the fire extinguishing means for sufficient time to allow all or a substantial part of the fire extinguishing medium to be expelled from the storage reservoir. The pressure generating means may take any suitable form, for example, it could be mechanical in nature, e.g. it may include a piston arrangement within the storage reservoir. Preferably the pressure generating means includes a gas-generator, e.g. a physical (i.e. pressurised) or a chemical gas generator. Suitable pressure generating means will be well known to the skilled man and include those used as pressure generators in other fields such as those used in vehicle safety air-bags, or in the starting motors of diesel engines or those used in powered model aircraft and boats. Gas generators as used in conventional fire extinguishing systems will, of course, be particularly suited to the present invention. These include chemical compounds capable of generating a gas upon activation and pressurised gas containers, e.g. cartridges, which can release their pressurised gas contents. The pressure generating means is preferably automatically activatable, although it may alternatively or additionally be manually activatable. The atomisation device has the function of converting the fire extinguishing medium from the form in which it is stored in the storage reservoir, generally as a fluid, into an atomised form so that it can be discharged from the apparatus in the form of a dispersed liquid cloud. The atomiser head is preferably provided with more than one, and most preferably a plurality of outlet nozzles through which pressurised fire extinguishing medium from the storage reservoir can be forced. The valve should be capable of preventing exit of fire extinguishing medium from the storage reservoir until the time of actuation of the apparatus. The valve may take the form of a barrier which is impermeable to the fire extinguishing medium until actuation at which time it becomes permeable to the fire extinguishing medium. Alternatively the valve may be a mechanical valve and in particular one operable from a closed position to an open position upon actuation. The valve preferably takes the form of a thin barrier or membrane removable or piercable upon actuation of the apparatus. It is particularly preferred that the valve be actuated, i.e. allow passage of fluid extinguishing medium, upon application of pressure such as that generated by the pressure generating means. The atomisation head should be arranged such that pressurised fluid being forced out of the storage reservoir after passing through the atomiser head leaves the apparatus at an elevated pressure, eg at pressures over 20 and more particularly over 40 bar. The fire extinguishing apparatus of the present invention is preferably capable of self or automatic activation in the presence of an external circumstance for which activation is desired / e.g. the commencement of a fire or the presence of an intruder. The apparatus may be provided with a detector capable of detecting the required external circumstance. The detector may be internal or external and integral or separate from the main body of the apparatus. When the detector senses the appropriate external circumstance there is preferably automatic activation of the pressure generating means causing pressure to be generated within the storage reservoir, which pressure preferably in turn causes opening of the valve controlled passage way releasing fire extinguishing medium contained in the storage reservoir to the atomisation device. Trigger of the detection means may also cause automatic activation of the charge generating means. There may also be means for providing automatic activation of an alarm signal, either visual and/or audio, for a predetermined period after the appropriate external circumstances have been detected. The detector, detection unit or sensor may take any suitable form. For detecting the presence of an intruder an infra-red sensor may be provided. For the detection of fire heat triggered sensors such as those used conventionally in fire extinguishing systems may be used. Such triggers may include the use of a liquid capsule which fractures when a certain temperature has been reached due to the expansion of fluid contained therein. The storage reservoir may take any suitable form, e.g. any suitable vessel for the storage of fire extinguishing medium. Preferably it is provided with a storage capacity of up to five litres, and preferably of one to two litres. It is preferably formed of a light-weight material but one strong enough to cope with the pressures generated upon activation of the apparatus. The fire extinguishing medium for use in the apparatus according to the present invention is preferably a liquid and most preferably water. The fire extinguishing medium may be provided with additives. Suitable additives include components capable of lowing the freezing point, e.g. antifreeze for water, antibacterial compounds and marker compounds. The addition of marker compounds may be used to indicate that activation of the apparatus has taken place. Such marker compounds preferably leave a visible, but easily removable, marker such as a suitable chemical material. The apparatus of the present invention may be fully manually operable, for example, it may take the external form of a conventional hand operated fire extinguisher. Alternatively the apparatus may be used as a self-contained, independent fully automatic fire extinguishing system. For this purpose the apparatus may be provided as a fixture on room fixtures, walls or ceilings. The apparatus is suitable for use in domestic, public or commercial situations and for both temporary or permanent purposes. The apparatus of the present invention may be used in methods of fire extinguishing and security and intruder identification. The present invention is advantageous as the atomisation of a fire extinguishing medium is aided by the use of an electrode system that allows each droplet to be raised to a charged, e.g. negative, electrical potential. The repulsive forces between the charged atomised droplets reduce the pressure needed for atomisation and greatly increases the time for which they remain in air suspension. The mutual repulsion between the electrified droplets will also cause a fog to spread rapidly throughout any volume, whatever the actual position from which it is released. Further, with a fire the nature of the combustion process is such that it generates an excess of positive ions: thus a flame is naturally attractive to negatively charged particles, causing them to move towards a negatively charged discharge from apparatus according to the present invention . For a better understanding of the present invention and to show how it may be put into effect, reference will now be made, for the purposes of illustration onh . to the accompanying drawings in which: Figure 1 is a schematic cross-sectional view of one embodiment of apparatus according to the present invention; and Figure 2 is a schematic flow diagram illustrating use of a further embodiment of the present invention. As shown in Figure 1 , with one embodiment of apparatus (1 ) according to the present invention, a small volume ( 1 or 2 litres) of a liquid (2) such as water is stored in a light, strong storage vessel (3). The liquid (2) may contain suitable additives such as antifreeze, anti-bacterial chemicals and marker compounds. The apparatus (1) may be placed in any convenient position, such as within a false ceiling, behind coving or another architectural feature, in a high corner or upon the surface of a wall or ceiling of a room in an office area, a hotel or a family dwelling. The apparatus (1) may also be fitted in a passenger lift. At one end of the vessel (3) there is provided a chemical gas generator (4) and at the other end an outlet passage (5). Across the outlet passage (5) a valve in the form of a thin membrane (6) is stretched. On the other side of the membrane (6) is an atomiser head (7) provided with several nozzles (9) that are normally sealed by the thin membrane (6) lining the inside of the outlet from the vessel (3) so preventing leakage of the liquid (2) contained therein. Between the source of liquid (2) and the external surface of the atomiser assembly, there is arranged electrostatic charge deposition means (8) shown schematically. The charge deposition means includes an electrical insulator separating two electrodes to which electricity can be supplied in such a way as to deposit a negative charge on each liquid droplet. This aids the dispersion of the fog and causes it to be attracted to the combustion zone, as previously described. Upon the detection of a fire in the area, by means of an internal sensor or upon the receipt of signal from an external fire detector, the small chemical gas generator (4) is triggered within the vessel (3) containing the liquid (2). Such a gas generator (4) might be similar to those commonly used in vehicle safety air bags, or those used for the starting of diesel motors or to power model aircraft and boats. Alternatively, a small capsule of high-pressure gas might be employed, such as those used in soda siphons. The release of gas from the gas generator (4) applies a pressure of several hundred psi. to the surface of the liquid (2) for a few seconds, so that the liquid (2) bursts through the thin membrane (6) which had previously prevented it from reaching the holes of the atomiser nozzles. During the time for which the gas pressure is applied, the liquid (2) is therefore expelled in all directions to form a dense fog in the region surrounding the device. It will be understood that the spurious firing of the fog generator i.e. apparatus, is to be avoided and the apparatus may include an electronic control means, so contrived as to ignore spurious signals such as those that might arise from local electromagnetic interference, from a mobile telephone, for example. During the pre-triggering period, the control electronics may be arranged to sound an alarm signal and to display an indication which continues for some while after the device has fired. It may be another function of the control means to monitor the readiness of certain components of the apparatus, e.g. of any stored electrical unit, and to emit a warning signal if, for example, a battery condition is unsatisfactory. With a fully automated embodiment, as described in relation to Figure 2, in use liquid is stored in a pressure vessel (box 1), within which is a thin membrane that prevents the liquid escaping through atomiser holes. The liquid is exposed to a generator of gas (box 2), e.g. a high pressure gas generator such as a chemical cartridge, which, when triggered, pressurises the container (box 1) rupturing the membrane and forcing the liquid to be expelled via an atomiser and distributor unit or arrangement (box 3). The apparatus contains a source of stored electrical energy (box 4), e.g. a battery, which is used both to operate the trigger device and to cause an electrostatic charge generator (box 5) to become active so as to electrify the liquid droplets via electrostatic charge deposition means (box 6), e.g. electrostatic charging electrodes. An electronic control means (box 7) having internal fire sensor and control electronics is employed to prime the electrical charge generator means (box 5) and to check that it is so primed before the firing of the gas generator (box 2). Audible and visual indicator means (box 8) are provided for alarm and checking purposes. The apparatus includes external control interface means (box 9) to which a separate fire detector unit may be connected or by which an external monitoring and control system can supervise a bank of extinguishers if these are distributed throughout a building or an open-plan office, for example. Whilst the preceding paragraph relates to a fixed, automatic form of the fire extinguishing apparatus, it will be evident that a manually-operated portable form of the apparatus may be constructed, merely by replacing the items of boxes (7), (8) and (9) by a hand-operated trigger or push-button and by arranging for the physical form of the device to be of a convenient nature - perhaps similar to existing portable fire extinguishers. Further, it is to be noted that with automatic embodiments of the present invention. there mav result circumstances in which it is common for the device to have operated, to have extinguished a small fire and for the fog to have dispersed, leaving the protected area dry again before a human being re-enters the region. It may therefore be a useful design feature for the operation of the extinguisher to leave visible evidence of its action and of the region over which the fog was dispersed. The liquid in the storage means may, therefore, have in solution a chemical that dries to leave a harmless coloured powder as evidence of extinguisher operation. Further, the inclusion of a chemical that is dispersed by the operation of the fog device will permit the application of the invention to be extended into the security systems market. That is to say, it would be possible for an embodiment of the invention when triggered by a security system that detects an unauthorised intruder in its vicinity, to release a dense fog that will not only alarm and confuse the intruder but will surround and coat his clothing and skin surfaces. In the case of a security fog device we therefore conceive that the chemical dissolved in the fog droplets might be a specific marker dye that will allow the intruder to be clearly identified.

Claims: CLAIMS 1. Apparatus for use as a fire extinguishing or security device comprising: a storage reservoir for the storage of fire extinguishing medium: an atomisation device comprising an atomiser head provided with at least one nozzle for the passage of fire extinguishing medium from the storage reservoir to the exterior of the apparatus and a valve for controlling the passage of fire extinguishing medium from the storage reservoir to the atomiser head: pressure generating means capable of applying pressure to fire extinguishing medium stored in the storage reservoir; and charge generating means capable of applying charge to the fire extinguishing medium, the arrangement being such that upon actuation of the apparatus fire extinguishing medium stored in the storage reservoir is forced out of the apparatus in a charged, atomised form. 2. Apparatus according to Claim 1 , wherein the charge generating means is capable of applying a negative charge to the fire extinguishing medium. 3. Apparatus according to Claim 1 or 2. wherein the charge generating means includes a pair of electrodes. 4. Apparatus according to any preceding claim, wherein the charge generating means is automatically activated. 5. Apparatus according to any preceding claim, wherein the pressure generating means is capable of applying a pressure of at least one hundred psi. 6. Apparatus according to any preceding claim, wherein the pressure generating means is capable of applying pressure for sufficient time to allow all or a substantial part of the fire extinguishing medium contained in the storage reservoir to be expelled therefrom. 7. Apparatus according to any preceding claim, wherein the pressure generating medium is a gas generator. 8. Apparatus according to any preceding claim, wherein the pressure generating means is automatically activated. 9. Apparatus according to any preceding claim, wherein the atomiser head is provided with a plurality of nozzles. 10. Apparatus according to any preceding claim, wherein the valve is a thin barrier or membrane breakable upon application of pressure to allow the passage of the fire extinguishing medium. 1 1. Apparatus according to any preceding claim, wherein, the apparatus is additionally provided with a detector for detecting an external circumstance for which activation of the apparatus is required. 12. Apparatus according to Claim 11, wherein the detector includes a heat sensitive sensor. 13. Apparatus according to any preceding claim, wherein the storage reservoir has a capacity of up to five litres. 14. Apparatus according to any preceding claim, in which the storage reservoir contains fire extinguishing medium and wherein the fire extinguishing medium is a liquid. 15. Apparatus according to Claim 15, wherein the liquid is water. 16. Apparatus according to Claim 14 or 15, wherein the liquid contains a marker compound. 17. Apparatus according to any preceding claim, wherein the apparatus takes the form of a manually operable device. 18. Apparatus according to any one of Claims 1 to 16. wherein the apparatus takes the form of a fully automatic, self-actuating and self-contained fire extinguishing system. 19. Apparatus as substantially hereinbefore described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings. 20. A method of extinguishing a fire which comprises applying to a conflagration a charged atomised liquid.

Inventors: DENNE PHILLIP RAYMOND MICHAEL, DENNE, PHILLIP, RAYMOND, MICHAEL
Applicants: DENNE PHILLIP RAYMOND MICHAEL, DENNE, PHILLIP, RAYMOND, MICHAEL
Application year: 1999
Main classification: A62C35
IPC codes: A62C35