GB2271058A

GB2271058A - Automatic fire-extinguishing system

Info

Publication number: GB2271058A
Application number: GB9317443A
Authority: GB
Inventors: Don Henry Dawson
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-21
Filing date: 1993-08-20
Publication date: 1994-04-06
Anticipated expiration: 2013-08-20
Also published as: GB9317443D0; GB2271058B; GB9217877D0

Abstract

A fire-extinguishing system comprises: (i) A vessel containing a fire-extinguishing materials, e.g. water or water based foam; (ii) At least one heat-sensitive delivery means for controllably releasing the fire-extinguishing material in response to the presence of excessive heat e.g. a sprinkler/frangible bulb arrangement; (iii) A distribution tube connecting the vessel with the heat-sensitive delivery means; (iv) A connector assembly adapted to connect the vessel and distribution tube; (v) A bleed means adapted to bleed air or gas from the distribution tube. The above components are arranged such that when the system is primed and ready for use the distribution tube and delivery means contain fire-extinguishing material but substantially no air. Also disclosed is a method of extinguishing fires or protecting against fire damage using the above fire extinguishing system. The present system may be incorporated in vehicles including agricultural machinery e.g. combine harvesters. The system may also incorporate an alarm device. <IMAGE>

Description

AUTOMATIC FIRE EXTINGUISHING SYSTEM Field of the Invention This invention relates to an automatic fire-extinguishing system for use in vehicles or machinery, especially mobile machinery such as combine harvesters.

Backaround to the Invention There have been many instances of fires occurring in combine harvesters, and because it is necessary to isolate the operator from the dust and noise of the machinery by providing a soundproofed and air conditioned control cab, it is possible for the fire to become serious before the operator is aware of it. On several occasions, this has led to destruction of the machine and to damage to the surrounding crop.

This can represent a substantial financial loss.

As motor cars become more and more complex electrically, the instances has of car fireslalso become more frequent. Car fires usually lead to destruction of the car, and can, of course, represent a substantial hazard to the occupants of the car. Similar considerations apply to boats, especially smaller sea-going and inland waterway boats.

The present invention provides a fire-extinguishing system suitable for useioreducing these dangers.

Summarv of the Invention According to the invention, there is provided a fire extinguishing system comprising a vessel containing a fire-extinguishing liquid under pressure, and at least one heat-sensitive external means in communication with the liquid in the vessel for releasing the liquid in response to the presence of excessive heat.

Preferably, the heat-sensitive means is a sprinkler head suitably connected to the vessel via a flexible tube, for example of synthetic rubber. The sprinkler head is suitably of the type commonly used in fixed fire-extinguishing systems in buildings, having a vial of a liquid with a high coefficient of thermal expansion such as to cause the vial to rupture, releasing a sealing plunger which in turn releases the liquid. Alternatively, or additionally, the heat-sensitive means may be a sealed flexible tube of a material which will melt when exposed to fire, thereby releasing the liquid under pressure therein to extinguish the fire. Thus, where sprinkler heads are spaced along a flexible rubber tube at intervals, if a portion of the tube intermediate two heads is exposed to fire, rupture of the tube itself will serve to release the liquid to extinguish the fire.

The vessel can be a pressure cylinder of the type used in conventional portable fire extinguishers. The pressure may be provided by introducing compressed air or nitrogen into the cylinder through a suitable non-return valve. In the case of compressed air, a valve of

the Schraeder type used on motor vehicle tyres, is suitable.

A The vessel is preferably provided with means for providing an electrical signal in response to a predetermined drop in the pressure in the vessel. For example, the vessel may have a pressure switch held open by the pressure in the vessel and set to close when the pressure drops, the switch forming part of an alarm circuit to provide an alarm signal indicating either that a fire has caused release of the fire-extinguishing liquid, or that pressure has been lost in the vessel as a result of a leak.

The fire-extinguishing liquid will typically be water or a water-based foam, but other liquids, or even gases or powders, can be used for special applications.

The invention provides a system which can readily be installed in a vehicle, in mobile agricultural machinery or in fixed machinery requiring localised fire protection. The system can not only extinguish the fire automatically, but can also be configured to provide a remote warning of the existence of the fire (or of potential failure of the system itself).

Brief Description of the Drawings In the drawings, which illustrate one example of a system according to the invention: Figure 1 is a diagram of the system; and Figure 2 is a circuit diagram of an electrical warning unit for a plurality of the systems of Figure 1 installed in, for example, the same vehicle.

DescriDtion of the Illustrated Embodiments Referring to Figure 1, the system comprises a cylinder 10 containing water 11 with suitable foaming agents. A water discharge tube 12 extends to a position adjacent to the bottom of the cylinder 10, and communicates via a connector assembly 13 in the upper end of the cylinder 10, with a distribution tube 14 of a synthetic rubber. The tube 13 has two sprinkler heads 15 connected therein at intervals therealong, and is terminated with a third sprinkler head 16 on an elbow joint. The sprinkler heads 15 and 16 are suitably coupled to the tube 14 by compression fittings of conventional form.

The connector assembly 13 comprises a chamber isolated from the discharge tube 12 but communicating with a gas space 17 above the water 11. A pressure gauge 18 is screwed into the assembly 13 and communicates with the chamber through a spring valve which closes when the gauge is removed for maintenance purposes, for example, leaving the chamber sealed. Also connected to the chamber are a Schraeder type inlet valve 19, by which compressed air may be introduced to pressurise the cylinder, and a pressure switch 20, the body of which is formed of stainless steel to resist corrosion, and which is adjustable to close when the pressure in the chamber falls below a predetermined value in the range 2 to 20 bar.

The switch 20 forms part of an electrical warning circuit comprising a 12V d.c. supply 21 (for example the battery of the vehicle on which the system is mounted), an audible alarm 22 and a warning lamp 23. Thus, when the pressure in the cylinder 10 drops, either because a fire has activated one or more of the sprinkler heads 15 and 16 or because of a leak in the cylinder or in the tube 14 or its connections, the switch 20 closes, completing the circuit through the audible alarm 22 and lamp 23, which, being located in the control cab, alert the driver or operator.

The cylinder is suitably of 0.5 to 5 gallons (2.2 to 22 litres) capacity, with the length of distribution tube 14 being up to 3m for a 9 litre cylinder, with any number of sprinkler heads along it. In its simple form, the system may comprise one sprinkler head connected to the cylinder by a short length of tube, for example 1 foot (0.3048m).

The sprinkler heads suitably have glass bulbs as the expansion elements, rated in the range 68 to 1400 Celsius.

To pressurise the system, the sprinkler head 16 furthest from the cylinder 10 would have to be loosened to "bleed" all air from the system, and then retightened. Bleeding of the air (or other propellant gas) from the system is important, because the initial blast of gas from the ruptured sprinkler heads if unbled could cause burning material to be blown over a wider area, thus spreading the fire and, in the case of compressed air, fan the fire to burn more fiercely. After bleeding, the entire system is under pressure and therefore ready to deal with any fire adjacent to it.

The distribution tube with its sprinkler heads can be fixed in position by using, for example, U-clamps on rubber mounts with the sprinkler heads situated in areas where there is greatest risk of fire, for example in engine compartments and near bearings which might overheat.

Bearings in remote compartments can be protected by simply drilling a small hole in the wall of the compartment to insert a sprinkler head, with the cylinder being mounted outside the compartment.

Transport brackets 24 are used to hold the cylinder in position.

Referring now to Figure 2, a combine harvester may have several separate fire extinguishing systems of the type illustrated in Figure 1 to cover all the potentially hazardous areas. For example, a large machine might require up to eight such systems. To monitor these separate systems, the operator's cab is provided with an indicator panel 25 having eight indicator lamps 26, each connected to a pressure switch 20 of a respective cylinder and to a test circuit 27 comprising a test switch 28 to short circuit all the pressure switches and thus show that all the indicator lamps 26 are functioning. A single alarm 29 is connected in the circuit, which is supplied with power from its own power supply (battery) 30, or from the vehicle's battery.

The indicator lamps 26 enable the operator immediately to identify the location of a fire or failure of pressure in one of the systems. Instead of - or as well as - unscrewing the sprinkler head 16, a "bleed" facility could be provided by incorporating a bleed-valve at a suitable point in the line.

Claims

1. A fire-extinguishing system comprising: (i) A vessel containing a fire-extinguishing material; (ii) At least one heat-sensitive delivery means for controllably releasing the said fire-extinguishing material in response to the presence of excessive heat; (iii) A distribution tube connecting the said vessel with the said heat-sensitive delivery means; (iv) A connector assembly adapted to connect the said vessel and said distribution tube; (v) A bleed means adapted to bleed air or gas from the distribution tube; The above components being arranged such that when the system is primed and ready for use the distribution tube and delivery means contain fire-extinguishing material but substantially no air.

2. A fire-extinguishing system as claimed in Claim 1 where in the fire extinguishing material is water or water-based foam.

3. A fire-extinguishing system as claimed in Claims 1 or 2 wherein the heat-sensitive delivery means is a sprinkler head of the type commonly used in the fixed fire-extinguishing systems found in buildings, having a vial of a liquid with a high coefficient of thermal expansion such that on exposure to excessive heat, this causes the vial to rupture, releasing a sealing plunger which in turn releases the fire-extinguishing material.

4. A fire-extinguishing system as claimed in any of Claims 1-3 wherein the connector assembly incorporates a non-returnable valve adapted for pressurizing the system with a fluid.

5. A fire-extinguishing system as claimed in Claim 4 wherein the non return valve is of the SCHRAEDER-type as used on motor vehicle tyres.

6. A fire-extinguishing system as claim in any of Claims 1-5 wherein the system is pressurized by the introduction of nitrogen or compressed air.

7. A fire extinguishing system as claimed in any of Claims 1-6 wherein the system is portable.

8. A fire-extinguishing system as claimed in any of Claims 1-7 wherein the system is adapted to be installed in a vehicle or other form of transport such as a boat, caravan or the like.

9. A fire-extinguishing system as claimed in any of Claims 1-8 wherein the system is adapted to be installed in mobile agricultural machinery or in fixed machinery requiring fire protection.

10. A fire-extinguishing system as claimed in any of Claims 1-9 wherein the system is adapted to be installed in a combine harvester.

11. A fire-extinguishing system as claimed in any of Claims 1-10 wherein the system incorporates an alarm device to alert an operator to the existence of a fire or a potential failure of the system itself, said device providing a means adapted to provide an alarm signal in response to a pre-determined drop in the pressure in the said vessel.

12. A fire-extinguishing system substantially as described herein with reference to and as illustrated in any appropriate combination of the accompanying drawings.

13. A method for extinguishing fires or protecting against fire damage comprising the steps of: (a) Providing a fire-extinguishing system as claimed in any of Claims 1-12; (b) Installing said system in a vehicle, machinery or item to be protected, positioning the heat-sensitive delivery means in close proximity to the areas most likely to overheat or catch fire; (c) Pressurizing the system with a compressed gas whilst bleeding air from the delivery means/distribution tube; (d) Activating the alarm device (if fitted).

14. A method of extinguishing fires or protecting against fire damage as described herein with reference to and as illustrated by any combination of the accompanying drawings.