WO2002060538A1

WO2002060538A1 - Fire extinguisher

Info

Publication number: WO2002060538A1
Application number: PCT/NL2002/000071
Authority: WO
Inventors: Jacobus Van Liere
Original assignee: N.V. Kema
Priority date: 2001-02-02
Filing date: 2002-01-30
Publication date: 2002-08-08
Also published as: NL1017266C2

Abstract

The invention relates to a fire extinguisher, comprising an atomizing device for atomizing water at high pressure, wherein the fire extinguisher comprises at least one atomizing nozzle which is directed at a component of an electrical appliance comprising a substantial quantity of combustible material. The present invention thus provides the measure that the fire extinguisher comprises at least one atomizing nozzle which is directed at a component of an electrical appliance, electrical circuit and the like comprising a substantial quantity of combustible material. According to a first embodiment the atomizing nozzle is directed at that component where the chance of fire is greatest. The majority of occurring fires can hereby be extinguished without movable parts and without human intervention.

Description

FIRE EXTINGUISHER

The present invention relates to a fire extinguisher, comprising an atomizing device for atomizing water at high pressure.

Such fire extinguishers are generally known. They derive their extinguishing action from the fact that the atomized particles evaporate, whereby heat is extracted from the fire so that the temperature thereof falls. The atomized particles furthermore displace oxygen.

Atomized particles have the property however that they reduce the breakdown voltage of the air. When used in electrical installations in which high voltages prevail, the present inventors have found that the extinguishing effect is greater than the stated igniting effect.

The present invention thus provides the measure that the fire extinguisher comprises at least one atomizing nozzle which is directed at a component of an electrical appliance, electrical circuit and the like comprising a substantial quantity of combustible material .

According to a first embodiment the atomizing nozzle is directed at that component where the chance of fire is greatest.

The majority of occurring fires can hereby be extinguished without movable parts and without human intervention. In order to increase the effectiveness, the atomizing nozzle is adapted according to a preferred embodiment to generate a cloud of mist .

A rotating cloud of mist results in a fine atomizing, so that the surface area of the atomized particles is enlarged and the extinguishing effect enhanced.

According to another preferred embodiment the at least one atomizing nozzle is adapted to produce a cone-shaped cloud of mist.

The high pressure in a cone-shaped cloud of mist results in a smaller sensitivity to wind, so that the cloud of mist can be directed better and the extinguishing action is optimal .

This effect is further enhanced when the at least one atomizing nozzle is adapted to form a cone-shaped cloud of mist, the top angle of which is smaller than 20'.

According to yet another preferred embodiment the fire extinguisher comprises a pressure generator which is adapted to generate a pressure in the atomizing nozzle of between 120 and 150 bar. A pressure generator can be understood to mean a pump, or for instance a pressurized air storage vessel.

This pressure range results in a more effective atomizing with smaller atomized particles.

Another preferred embodiment is atomizing of water at high pressure (40-150 bar) and increased temperature (150- 250'C), whereby a mist results with extremely small particle size (1-5 μm) .

Yet another embodiment teaches that the effectiveness of the fire extinguisher is greatly enhanced when the electrical appliance is placed in a housing, which housing is provided with at least one opening closed by an element, and that the fire extinguisher is adapted to direct the at least one cone at the at least one element .

This embodiment is particularly applicable when the electrical appliance is placed in a housing filled with oil and the elements closing the openings are formed by a high- voltage throughfeed, a cover of a control unit or by a cover of a pressure-relief valve.

Other attractive preferred embodiments are stated in the remaining sub-claims.

The present invention will be elucidated hereinbelow on the basis of the annexed figures, in which: figure 1 is a perspective view of a part of a fire extinguisher according to the present invention; and figure 2 is a top view of a power transformer provided with a fire extinguisher according to the invention.

As already stated in the preamble, the device according to the present invention is most effective when the atomized particles are directed at the location where the fire originates. In order to be effective however, the mist cone takes up a limited volume, so that it is important that the cone is well directed. In practice this often causes difficulties, since it is not possible to anticipate precisely where the fire will originate. Experience has shown however that, in the case of fires in electrical high-voltage appliances accommodated in an oil-filled housing, the fire usually originates in an opening in the housing, for instance at the position where a throughfeed is arranged which closes the opening. The chance of fire as a result of for instance oil leakage is greatest at the boundary surface between the housing, in this case cover, and throughfeed.

Figure 1 thus shows a transformer housing designated as a whole with 1. Transformer housing 1 is covered on its upper side by a cover 2. Arranged in cover 2 of the transformer housing is a high-voltage throughfeed designated as a whole with 3. The high-voltage throughfeed is formed by an insulator 4 resting on a console 5, which console 5 is placed on cover 2. High-voltage line 6 exits on the upper side of the insulator.

The chance of a fire originating in the vicinity of such a high-voltage throughfeed is greatest at the boundary surface between insulator 4 and console 5. In order to extinguish a fire possibly occurring here, a horseshoe-shaped pipe 7 is arranged around insulator 4. For this purpose horseshoe-shaped pipe 7 is mounted on two supports 8. The horseshoe shape of pipe 7 is chosen so as to arrange the pipe partly around insulator 4 without the insulator having to be removed.

The horseshoe-shaped pipe 7 is provided with a number of atomizing nozzles 9 which are each adapted to generate a cone-shaped or parabolic mist of water.

It is necessary for this purpose for water to be supplied to the pipe under very high pressure. Use is made for this purpose of a feed pipe 10 which is connected to a ring conduit 11 extending around the transformer. Ring conduit 11 is connected to a pump for generating a high pressure, for instance a plunger pump. Use is preferably made herein of a pressure in the order of magnitude of 120-150 bar. Experience has shown that this high pressure results in a good cone-shaped cloud of mist with a sufficiently fine atomization of the water.

The transformer is of course provided with a larger number of high-voltage throughfeeds . For each of the high- voltage throughfeeds a device will therefore have to be arranged as shown in figure 1. Such a situation is shown in figure 2. This figure once again shows a transformer provided with a number of high- voltage throughfeeds . Arranged around each of these high- voltage throughfeeds is a horseshoe-shaped pipe 7 which is provided with a number of atomizing nozzles, wherein the atomizing nozzles are adapted to direct a number of cone- shaped clouds of mist at the boundary surface of insulator and transformer surface .

In this embodiment pipes with atomizing nozzles are arranged not only around the high-voltage throughfeeds, but also around the cover of the controller. This is also a position at which an opening in the transformer vessel is arranged which is closed by a cover. The chance of fire occurring is here also considerably greater than elsewhere on the transformer vessel . It is thus for instance also possible to arrange such a fire extinguisher on other externally arranged Buchholtz relays or on another safety device.

The application of the invention is not limited only to transformers; other electrical appliances can also be protected with such a fire extinguisher; envisaged here are choke coils, power-cutout switches, cable terminals or other components where a certain degree of fire hazard is present.

It is finally pointed out that the investment for a fire-extinguishing installation according to the present invention is quite small in comparison with prior art fire extinguishers which can for instance be applied in the case of transformers. As shown in the drawings, only relatively thin pipes are necessary since the total quantity of water is extremely small. This is contrast to the prior art wherein much larger amounts of water are used during extinguishing. This otherwise also has the environmental drawback that the large quantities of fire-extinguishing water have an environmental impact because they are usually contaminated.

Claims

1. Fire extinguisher, comprising an atomizing device for atomizing water at high pressure, characterized in that the fire extinguisher comprises at least one atomizing nozzle which is directed at a component of an electrical appliance comprising a substantial quantity of combustible material.

2. Fire extinguisher as claimed in claim 1, characterized in that the atomizing nozzle is directed at that component where the chance of fire is greatest .

3. Fire extinguisher as claimed in claim 1 or 2, characterized in that the atomizing nozzle is adapted to generate a swirling cloud of mist.

4. Fire extinguisher as claimed in claim 1, 2 or 3 , characterized in that the at least one atomizing nozzle is adapted to produce a cone-shaped cloud of mist.

5. Fire extinguisher as claimed in claim 1, 2, 3 or 4, characterized in that the at least one atomizing nozzle is adapted to form a cone-shaped cloud of mist, the top angle of which is smaller than 20".

6. Fire extinguisher as claimed in any of the foregoing claims, characterized in that the fire extinguisher comprises a pressure generator which is adapted to generate a pressure in the atomizing nozzle of between 120 and 150 bar.

7. Fire extinguisher as claimed in any of the foregoing claims, characterized in that the fire extinguisher comprises a pressure generator which is adapted to generate a pressure in the atomizing nozzle of between 40 and 150 bar and a temperature between 150-250 'C.

8. Fire extinguisher as claimed in any of the foregoing claims, characterized in that the electrical appliance is placed in a housing, which housing is provided with at least one opening closed by an element, and that the fire extinguisher is adapted to direct the at least one cone at the at least one element .

9. Fire extinguisher as claimed in claim 8, characterized in that the electrical appliance is placed in a housing filled with oil, and that the elements closing the openings are formed by high-voltage throughfeed, a cover of a control unit or by a cover of a pressure-relief valve.

10. Fire extinguisher as claimed in claim 9, characterized in that the fire extinguisher is placed on a power transformer.

11. Fire extinguisher as claimed in claim 8, 9 or 10, characterized in that the fire extinguisher comprises a pipe connected to the pump and extending around the element closing the opening, which pipe is provided with atomizing nozzles which are adapted to direct a cone-shaped cloud at the element closing the opening.

12. Fire extinguisher as claimed in any of the claims 8- 11, characterized in that the fire extinguisher comprises a pipe connected to the pressure generator and extending around the cover of the housing, which pipe is provided with atomizing nozzles which are adapted to direct a cone-shaped cloud at elements arranged in the cover and closing the opening.

13. Fire extinguisher as claimed in any of the foregoing claims, characterized in that the fire extinguisher comprises a detection device for detecting a fire-indicating situation.