IL95543A - Method and apparatus for extinguishing a fire - Google Patents

Description

na'nis nmDi? mam HD'B METHOD AND APPARATUS FOR EXTINGUISHING A FIRE METHOD AND APPARATUS FOR EXTINGUISHING A FIRE The present invention is a patent of addition to Israel Patent No. 92951 and relates to a method and apparatus for extinguishing a fire.

Many diverse types of fire-extinguishing methods and apparatus are available today. Generally speaking, they extinguish the fire by one or more of the following techniques: inhibition of oxygen or fuel to support the fire; cooling the area in which the combustion is taking place; and/or interference in the chain reactions involved in the combustion. However, the existing methods and apparatus generally suffer from one or more of the following drawbacks: damage to the equipment; pollution of the environment; hazards to the operating personnel; high rate and high cost of false alarms; noise; and limited number of operations before replacement or refilling is required.

An object of the present invention is to provide a novel method, and also a novel apparatus, for extinguishing a fire having advantages in one or more of the above respects.

The present invention is based on the known phenomenon that fire behaves as a plasma, namely as a body of ionized gas having high concentrations of ions. For example, a "fire plasma" is a body of ionized gas having typical concentrations of 1010 to 1013 ions per cubic cm at standard temperature and pressure. The present invention exploits this phenonmena by causing the ionized gas of the "fire plasma" to interact with an externally-generated "plasma", or flow of ionized gas, and thereby to suppress the combustion process.

Accordingly, the present invention provides a method of extinguishing a fire, comprising: generating a flow of ionized particles in a gaseous flowable medium; and directing the flow of said gaseous flowable medium towards the base of the fire until the fire is extinguished.

According to a further feature in the preferred embodiment of the invention described below, the flow of the ionized particles is directed to the base of the fire by a nozzle having an outlet opening of relatively small cross-sectional area for increasing the velocity of the flow to the base of the fire.

A number of techniques are known for generating a flow of ionized particles in a gaseous flowable medium, including laser irradiation, and high energy electron bombardment in a gas. In the preferred embodiment of the invention described below, however, the flow of ionized particles is generated by a corona discharge. A corona discharge is an electrical discharge occurring when one of two electrodes in a gas, such as air, has a shape causing the electric field at its surface to be significantly greater than that between the two electrodes. The corona discharge is usually evidenced by a faint glow enveloping the high-field electrode and often accompanied by streamers directed towards the low-field electrode.

In the preferred embodiment of the invention described below, the corona discharge is generated b applying a high voltage between a first electrode structure having at least one point electrode, and a second electrode structure having a surface electrode spaced from the point electrode. The first electrode structure includes a plurality of point electrodes fixed at one of their ends to a common electrode base with their opposite ends facing the surface electrode of the second electrode structure.

According to further features in the preferred embodiment of the invention described below, the second electrode structure includes two surface electrodes disposed on opposite sides of the point electrodes and spaced to one side thereof, the edges of the two surface electrodes facing the point electrodes being spaced more widely apart from each other than their opposite edges so that their opposite edges define an elongated nozzle opening of relatively small cross-sectional area increasing the velocity of the ionized gas flowing between the two surface electrodes. In addition, the common electrode base of the first electrode structure is of generally concave or V-configuration, and the point electrodes are of generally needle configuration mounted in a line centrally of the concave common electrode base .

It will thus be seen that in the preferred embodiment of the invention to be described below, the ionized gas flow is generated by using corona discharge produced in air from a needle-point (actually a plurality of needle-points) to surface or planar electrodes. The ionized gas flow is concentrated and shaped by the combined action of the electric field and ion wind.

The flow of ionized particles may be generated in a movable device which is moved to direct the flow of ionized particles to the base of the fire. For example, the movable device may be a portable unit which is manually operated to produce the flow of ionized particles, and is manually manipulated, as by waving the device over the fire, to direct the flow to the base of the fire.

The flow of ionized particles may also be generated in a fixed device which is fixed relative to the location to be protected from fire, and which is automatically operated by a fire detector to generate the flow of ionized particles and to thereby extinguish the fire.

The flowable gaseous medium may be air or another gas, and may include non-ionizable particles as well as ionizable particles. For example, it may be or include a halogen gas, steam, or a powder. An example of a powder that may be included is mono-amonium phosphate .

One example, more particularly described below, utilizing a corona discharge in air was found capable of extinguising a 30 x 80 cm flame of hydrocarbon fuels utilizing a 30 kV 1 mA DC power supply.

Further features and advantages of the invention will be apparent from the description below.

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: Fig. 1 illustrates one form of apparatus constructed in accordance with the present invention; Fig. 2 is a top plan view of the electrode assembly in the apparatus of Fig. 2 for producing a flow of ionized particles in the form of corona discharge; Fig. 3 is a sectional view along line III--III of Fig. 2; and Fig. 4 illustrates another embodiment of the invention wherein the ionized particles generator is fixed with respect to the location to be protected from fire and is automatically operated by fire detectors.

The fire extinguishing apparatus illustrated in Figs. 1-3 is a portable device which may be manually carried by the operator to the location of the fire and then manually operated in order to extinguish the fire. The device includes a handle, generally designated 2, at one end for carrying and manipulating the device; an electrode assembly, generally designated 4, at the opposite end for producing a flow of ionized gas by a corona discharge in air; and a high voltage power supply, generally designated 6, for producing the corona discharge.

More particularly, handle 2 includes two hand-gripping sections 8, 10, to be gripped by the two hands of the operator in order to facilitate carrying and manipulating the device. Hand-grip 10 includes an operator button 12 conveniently located to operate the device .

Power supply 6 includes a source of high voltage which is applied to the electrode assembly 4 upon depression of the operator button 12. The power supply 6 may further include one or more indicator lamps 14 to indicate the status of the device, e.g., a Ready-Status, Operating-Status, etc.

The electrode assembly 4 includes two electrode structures, generally designated 20 and 30, respectively, supported in spaced relationship with respect to each other by a plurality of electrically-insulating supporting members, generally designated 40. Electrode structure 20 is connected to one terminal (either the positive or negative terminal) of the high-voltage supply 6, whereas electrode structure 30 is connected to ground, so that when the high voltage is applied between the two electrode structures, a corona discharge is produced to form a flow of ionized particles in a gaseous medium (air) through the end of the electrode assembly 4 opposite to that of handle 2.

Electrode structure 20, connected to the high-voltage terminal of the power supply 6, includes a base electrode 22 of generally concave or V-configuration and a plurality of point electrodes 24 of generally needle configuration fixed in a line along the center line of the base electrode 22. The needle electrodes 24 extend past the base electrode 22 towards electrode structure 30.

Electrode structure 30, which is connected to ground, includes two plate electrodes 32, 34 disposed on opposite sides of the needle electrodes 24 but spaced to one side of those electrodes . The two plate electrodes 32, 34 are curved in a converging manner away from the needle electrodes 24, so that edges 32a, 34a of the two plate electrodes are more widely spaced apart from each other than their opposite edges 32b, 34b. Electric structure 30 thus serves as a funnel or nozzle for receiving the ionized gas produced by corona discharge between the needle electrodes 24 and the plate electrodes 32, 34, and for discharging the flow of ionized gas at an increased velocity through the elongated nozzle opening between the two edges 32b, 34b of the plate electrodes.

The insulating members 40 for supporting the two electrode structures 20, 30 in spaced relationship include a pair of arms 41 , 42 on one side of the electrode assembly 4, and a second pair of arms 43, 44 on the opposite side of the electrode assembly. The two arms 41 , 43 are fixed at one of their ends to the base electrode 22 of electrode structure 20, and at their opposite ends they are pivotally mounted by pins 45, 46 to the inner ends of arms 42, 44. The outer ends of arms 42, 44 are pivotally mounted by pins 47, 48 to the two electrode plates 32, 34 of electrode structure 30.

The pivotal mountings 45, 46, 47, 48, permit angular adjustment of the two electrode plates 32, 34 of electrode structure 30 with respect to the needle electrodes 24 of electrode structure 20. Linear adjustment of electrode structure 30, towards and away from electrode structure 20, may be effected by providing the two arms 42, 44 with elongated slots, as shown at 49 in Fig. 3, adjacent to their respective pivotal mountings 45, 46.

The manner of using the device illustrated in Figs. 1-3 for extinguishing a fire will now be described.

Thus, the device may be hand-carried to the location of the fire, and its nozzle end (edges 32b, 34b) may be held above the base of the fire and waved back and forth as the operator button 12 is depressed. The depression of button 12 connects the high-voltage source 6 to the needle electrodes 24 of the electrode assembly 4 to thereby produce corona discharge between the needle electrodes and the two plates 32, 34 of electrode structure 30, connected to ground. The funnel configuration of the two plates 32, 34 increases the velocity of the ionized gas produced by the corona discharge as such ionized gas is discharged from the elongated opening defined by the edges 32b, 34b of electrode structure 30.

An electrode assembly was constructed as illustrated in Figs. 1-3, in which the two electrode plates 32 and 34 were 40 x 7 cm and were spaced apart 5 cm at their wide side and 1.5 cm at their narrow side. Electrode 22 was of a length of 40 cm, a width of 4 cm, and the ends of its diverging sections were spaced 4 cm. The needle electrodes 24 were of a length of 9 cm, had a diameter of 1 mm, and the sharp tips were spaced apart 4 cm. The electrode assembly was connected to a 30 kV 1 mA DC power supply, and was found capable of extinguishing a 30 x 80 cm flame of hydrocarbon fuels.

The extinguishing of the flame can be enhanced by including another gas, particularly a halogen gas, in the flowable air medium containing the ionizable particles. For example, a small amount of Halon 1301 gas (CF^Br) may be added to the air passed through the electrode assembly subjected to the corona discharge so that the air flow also includes Br- and CF^+ ions. When even a small amount of such a gas is added to the air subjected to the corona discharge, the latter ions enhance the fire extinguishing properties of the flowable gaseous medium.

The flowable gaseous medium may also include powders or an aerosal of known fire extinguishing agents, such as mono-amonium phosphate powder, which also enhances the fire extinguishing property of the flowable gaseous medium.

Utilizing a corona discharge for producing the ionized particles will also produce a "flow" or a "wind". This flow, however, can be increased by other means, such as by using a blower, or a compressed source of gas for the air, other gas (e.g., halogen), powder, or other flowable gaseous medium carrying the ionized particles to the base of the flame.

Fig. 4 diagrammatically illustrates the invention embodied in apparatus which is fixed relative to the location to be protected from fire and which is automatically operated by a fire detector to generate the ionized gas. Thus, the apparatus illustrated in Fig. 5 includes a fixed electrode assembly, similar to that illustrated in Figs. 1-4, at each location to be protected from fire, and a plurality of fire detectors 62 which control, via a central processor 64, a high voltage power supply 66 to produce a flow of ionized gas, e.g., by a corona discharge, automatically in response to the detection of a fire at the respective location.

While the invention has been described with respect to several embodiments, it will be appreciated that many other variations, modifications and applications of the invention may be made.

Claims (20)

- 12 - 95543/3 WHAT IS CLAIMED IS:

1. A method of extinguishing a fire, according to Claims 1-4 of Israel Patent No.92951, characterized in: generating a gaseous plasma constituted of a body of electrically-charged particles; and directing said plasma to the base of the fire until the fire is extinguished.

2. The method according to Claim 1 , wherein said plasma is generated by applying a high voltage between two electrodes separated by an air gap.

3. The method according to Claim 2, wherein said high voltage produces a corona discharge between said two electrodes.

4. The method according to Claim 1 , wherein said plasma is directed to the base of the fire by initially fixing the plasma at a location which would be in the vicinity of the base of a fire should a fire occur.

5. The method according to Claim 1 , wherein said plasma is directed to the base of the fire by mounting the plasma generator on a portable unit and manually directing the plasma to the base of the fire.

6. The method according to Claim 1, wherein a plasma is generated, and the flow velocity of the plasma is increased by directing the plasma via a nozzle to the base of the fire. - 13 - 95543/3

7. The method according to Claim 6, wherein another flowable medium is injected into the generated plasma to produce a plasma jet which is directed to the base of the fire.

8. The method according to Claim 7 , wherein said another flowable medium is or includes ionized particles .

9. The method according to Claim 7, wherein said another flowable medium is or includes non-ionized particles .

10. The method according to Claim 7, wherein said another flowable medium is or includes a fire suppressant material.

11. Apparatus for extinguishing a fire, according to Claims 5 and 6 of Israel Patent No.92951, characterized in that it includes : a generator for generating a gaseous plasma constituted of a body of electrically-charged particles ; and means for directing said plasma to the base of the fire until the fire is extinguished.

12. The apparatus according to Claim 11 , wherein said generator includes two electrode structures spaced by an air gap, and means for applying a high voltage to said two electrode structures to produce an electrical discharge therebetween. - 14 - 95543/2

13. The apparatus according to Claim 12, wherein said two electrode structures are configured to produce a plasma by a corona discharge.

14. The apparatus according to Claim 13, further including a nozzle for increasing the flow velocity of the plasma directed to the base of the fire .

15. The apparatus according to Claim 13, wherein one of said electrode structures includes at least one point electrode, and said other electrode structure includes a surface electrode spaced from said point electrode.

16. The apparatus according to Claim 15, wherein said one electrode structure includes a plurality of point electrodes fixed at one of their ends to a common electrode base with their opposite ends facing said surface electrode of the other electrode structure.

17. The apparatus according to Claim 16, wherein said other electrode structure includes two surface electrodes disposed on opposite sides of said point electrodes and spaced to one side thereof, the edges of the two surface electrodes facing the point electrodes being spaced more widely apart from each other than their opposite edges so that their opposite edges define an elongated nozzle opening of relatively small cross-sectional area increasing the velocity of - 15 - 95543/3 the flow of the plasma between the surface electrodes.

18. The apparatus according to Claim 17 , wherein said common electrode base of said one electrode structure is of generally concave configuration, and said point electrodes are of generally needle configuration mounted in a line centrally of said concave common electrode base.

19. The apparatus according to Claim 13, further including means for injecting another flowable medium into the generated plasma to produce a plasma jet which is applied to the base of the fire.

20. The apparatus according to Claim 1 , wherein said another flowable medium is a fire suppressant medium.