GB2293762A

GB2293762A - Extinguishing fires

Info

Publication number: GB2293762A
Application number: GB9419053A
Authority: GB
Inventors: Panos Papavergos
Original assignee: Kidde Graviner Ltd; Kidde Fire Protection Ltd
Current assignee: Kidde Graviner Ltd; Kidde Fire Protection Ltd
Priority date: 1994-09-20
Filing date: 1994-09-20
Publication date: 1996-04-10
Also published as: GB2293322A; GB9509601D0; GB9419053D0

Description

1 2293762 FIRE EXTINGUISHANT DISCHARGE METHOD AND APPARATUS The invention

relates to methods and apparatus for discharging fire extinguishants. Methods and apparatus to be described in more detail below, by way of example only, are for discharging fire extinguishants in the form of water or water-based fluids.

According to the invention, there is provided a method of fire extinguishing, comprising the steps of producing at least two jets of fluid directed in predetermined directions within the ambient atmosphere so as to impinge with each other, at least one of the jets being a jet of an extinguishing liquid which is atomised into a spray of drops by the impingement.

According to the invention, there is further provided a method of extinguishing fires, comprising the steps of emitting a plurality of first fluid jets into the ambient atmosphere in respective first directions from a nozzle, emitting a plurality of second fluid jets into the ambient atmosphere in respective second directions from the nozzle, the jets being so mutually positioned and the first and second directions being such that the jets of the two pluralities impinge on each other, the jets of at least one plurality being jets of a fire extinguishing 2 liquid which becomes atomised into drops by the impingement and produces a fire-extinguishing spray.

According to the invention, there is still further provided a spray nozzle for fire extinguishing purposes, comprising a body portion formed with at least two outlets for producing respective fluid jets into the ambient atmosphere which are mutually inclined so as to impinge with one another in the atmosphere, at least one of the fluid jets being a jet of liquid extinguishant which is atomised by the impingement into a spray of drops.

According to the invention, there is yet further provided a spray nozzle for fire extinguishing purposes, comprising a body portion formed with a plurality of first outlets for respectively emitting first fluid jets into the ambient atmosphere, a plurality of second outlets for respectively emitting second fluid jets into the atmosphere, the first outlets being positioned to direct the first jets parallel to each other and mutually spaced apart and the second outlets being positioned to direct the second jets in directions inclined to the first jets, each second jet being positioned to intersect with a respective one of the first jets so as to impinge with it in the atmosphere, at least one of each pair of intersecting jets being a jet of liquid extinguishant which 3 is atomised by the impingement into a spray of drops.

Methods and apparatus according to the invention for discharging a fire extinguishant in the form of a water spray will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a diagrammatic cross-section through one spray nozzle embodying the invention; and Figure 2 is a cross-section through another spray nozzle embodying the invention.

The water spray nozzle shown in Figure 1 comprises (in this example) a generally cylindrical body 5 having a cylindrical wall 6 and ends 8 and 10. The end 8 is closed ff by a wall defining a frusto-conically shaped portion 12 integral with and surrounded by a radially extending wall portion 14. The inclined side of the frusto-conically shaped wall portion 12 defines five (in this example) equally spaced outlets 16 of which two are shown. The radial end wall portion 14 also defines five (in this example) equally spaced through outlets 18 and, again, two are shown.

4 In addition, the nozzle includes an insert part 20. This comprises a cylindrical wall 22 having an end wall 24 incorporating a through bore 26. On the opposite side of the wall 24, the insert has a further cylindrical wall 28 having an open end 30.

A radial shoulder 32 integral with and extending annually around the wall 22 incorporates through bores 34; two of these are shown in the Figure, but there may be more than two, spaced around the shoulder 32.

The shoulder 32 supports an outer cylindrical wall 36 defining an annular space 38 extending around the opening 30.

The insert 20 is securely mounted within the cylindrical body 5 by means of a screw thread 46. The distal end of the wall 22 of the insert incorporates an O-ring 48 which seals against the inner face of the radial end wall 8 of the main body 5.

In this way, the main body 5 and the insert 20 together define a central chamber 50 which is in communication with the outlets 16 and an annular chamber 52 in communication with the outlets 18.

The lower portion (as viewed in Figure 1) of the cylindrical wall 6 is reduced in thickness and internally threaded at 54.

Each outlet 16 lies in the same radial plane (with respect to the longitudinal axis of the nozzle) as a respective one of the outlets 18.

In use, the nozzle is attached, by means of the internal thread 54, to a water supply pipe through which water is supplied at a pressure within the range 5 - 20 barg. The water passes into the central chamber 50 through the through bore 26 and into the annular chamber 52 through the bores 34. Thence, the water exits in jets through the outlets 16 and 18. The water supply to all the outlets 16,18 is common and thus at the same pressure. Because the outlets 16 are inclined with respect to the outlets 18, and the outlets 16 and 18 are aligned with each other (all on same radius from axis), the water jets from the outlets 16 impinge on those from the outlets 18, this impingement taking place close to the end wall 8 of the nozzle. As the emerging water jets impinge on one another, some or most of their kinetic energy is transferred to produce mutual shearing of the water, thus transforming the water jets into a rarified spray of fine drops. The drops, having acquired sufficient momentum 6 from the remaining kinetic energy of the emerging jets, form a directional spray, the throw of which is determined by the spray angle and water throughput. Air is entrained from the ambient atmosphere into the spray and this inhibits coalescence of the drops downstream of the nozzle. The spray of fine water drops thus produced is found to provide very effective fire extinguishment with the use of little water (as compared with deluge or sprinkler systems).

The characteristics of the water spray are affected by the relative angles of the impinging water jets and the positions at which they impinge on each other relative to the end wall 8 of the nozzle, and by the speed and size of the emerging water jets. The average drop size may be between 80 and 200 micrometres with 90% of the drops measured on a volume basis being less than 500 micrometres. The water spray characteristics are also affected by the amount of water allowed to pass through each set of outlets 16,18; this would be determined by the sizes of the through bores 26 and 34. All these various parameters can be adjusted to provide a water spray suited to a particular type of fire to be extinguished.

The momentum of the inner jets (the jets from the outlets 16) relative to that of the outer jets (from the outlets 7 18) determines the extent of liquid atomisation (the fineness or coarseness of the spray). It is also partly determined by the inclusive spray angle of the spray.

It will be noted that a significant feature of the nozzle is that atomisation of the water takes place externally of the nozzle body rather than inside the body.

The removable inner body 20 is advantageous from a manufacturing and constructional point of view. In addition, because the inner body 20 is removable, clearance of blockages and the like, and general cleaning, is facilitated. However, it will be understood that many other constructional arrangements are possible which have the effect of producing jets impinging on each other close to the outside of the nozzle to produce the required water spray. The sets of outlets 16,18 producing the jets can be arranged in any suitable way. They need not be arranged on respective circles as described above. Instead, for example, they, or at least one set, could be arranged on an eclipse or in any other way, such as along a straight or curved line.

Figure 2 shows another form of nozzle. Again, this is in two parts.

8 The outer body comprises a cylindrical wall 60 having an end wall 62 with a frusto-conical integral portion 64 similar to the portion 12 of the nozzle of Figure 1. The inclined side of the frusto-conically shaped wall portion 64 defines five (in this example) equally spaced outlets 16 of which two are shown. The radial end wall portion 66 also defines five (in this example) equally spaced through outlets 18 and, again, two are shown. The outlets 16 and 18 are arranged in the same way as the outlets 16 and 18 of the nozzle of Figure 1.

The inner body 68 of the nozzle of Figure 2 is of simpler construction than the inner body 20 of the nozzle of Figure 1. It comprises a generally cylindrical wall 70 which is externally threaded to engage an internal thread 72 formed at the lower end of the cylindrical wall 60 of the outer body. At its upper end (as viewed in Figure 2) the inner body 68 included an 0-ring 71 which makes a gas and water-tight seal against the inner face of the end wall 66.

In this way, the inner and outer bodies 68 and 60 def ine a central chamber 74 in communication with the outlets 16 and an annular chamber 76 in communication with the outlets 18.

9 Chamber 74 is connected to a connection port 78.

Chamber 76 is connected to a connection port 80 which is formed to extend radially through the wall 60 of the outer part 5 and thence through a bore 82.

Port 78 is internally threaded at 84 to enable it to be connected to a fluid supply pipe. Port 80 is internally threaded at 86 to enable it to be connected to a second fluid supply pipe.

In use, a suitable gas, such as air or nitrogen, is supplied through the fluid supply pipe connected to port 78 and exits under pressure in jets through outlets 16. Simultaneously, water (at the same order of pressure as for the nozzle of Figure 1) is supplied through port 80 from a separate pipe connected to the support, and exits in water jets through outlets 18. Because the exiting water jets are angled to the exiting air jets and aligned with them, impingement takes place, again resulting in the transfer of kinetic energy and producing shearing of the water jets so as to convert the water into a rarified spray of fine drops which are carried forward by the remaining kinetic energy of the emerging jets. The water drop size produced is of the same order as for the nozzle of Figure 1, or less. Again, the various parameters of the emerging jets can be controlled by appropriate adjustment of the applied pressures and by the mutual angle of impingement of the air and water jets and the size of the jets so as to produce the desired water spray characteristics (drop size distribution, spray angle, throw of spray and type of spray e.g. with a void within it).

As with the nozzle of Figure 1, no mixing or jet impingement takes place inside the nozzle. Pressure and flow variations of one fluid therefore have no effect on the pressure-flow characteristics of the other. In addition, because the air and water are kept separate until their respective jets impinge outside the nozzle, there is no need to take any precaution to prevent the water supply from entering the air supply.

gain, the removable inner body 68 enables easier manufacture and can be readily removed for cleaning and unblocking. Again, though, many modifications can be made to the construction.

Instead of supplying air or gas to the port 78 and water to the port 80, these may be reversed: that is, the gas can be supplied to port 80 and the water to port 78.

11 The water supply to the nozzles of Figures 1 and 2 can be from a mains supply or a stand-alone supply pressurised by means of a pump or by gas for example or even by a gas generating device, pyrotechnically operated. Any suitable control system may be used for activating the sprays.

Instead of water, any other suitable liquid extinguishant can be used which may advantageously, though not necessarily, be water-based. For the nozzle of Figure 2, any other suitable gas can be used.

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Claims

1. A method of fire extinguishing, comprising the steps of producing at least two jets of fluid directed in predetermined directions within the ambient atmosphere so as to impinge with each other, at least one of the jets being a jet of an extinguishing liquid which is atomised into a spray of drops by the impingement.

2. A method according to claim 1, in which the other jet is a jet of the same liquid.

3. A method according to claim 1, in which the other jet is a gas jet.

4. A method according to claim 3, in which the gas is air, nitrogen or other non-flammable gas.

5. A method of extinguishing fires, comprising the steps of emitting a plurality of first fluid jets into the ambient atmosphere in respective first directions from a nozzle, emitting a plurality of second fluid jets into the ambient atmosphere in respective second directions from the nozzle, the jets being so mutually positioned and the first and second directions being such that the jets of the two pluralities impinge on each other, the jets of at 13 least one plurality being jets of a fire extinguishing liquid which becomes atomised into drops by the impingement and produces a fire- extinguishing spray.

6. A method according to claim 5, in which the second predetermined directions are each intersectingly inclined with a respective one of the first directions, the first directions being parallel to each other.

7. A method according to claim 6, in which the first jets are spaced apart around a first circle and the first directions are directions parallel to the axis through the circle and the second jets are spaced apart around a second circle concentric with the first circle and the second directions are inclined with respect to the axes of the circles.

8. A method according to any one of claims 5 to 7, in which at least the second jets are the jets of the liquid extinguishant.

9. A method according to any one of claims 5 to 7, in which all the jets are jets of a liquid extinguishant.

10. A method according to any one of claims 5 to 8, in which the first jets are gas jets.

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11. A method according to claim 10, in which the gas is air, nitrogen or another non-flammable gas.

12. A method according to any preceding claim, in which the extinguishing liquid is water or a water-based substance.

13. A spray nozzle for fire extinguishing purposes. comprising a body portion formed with at least two outlets for producing respective fluid jets into the ambient atmosphere which are mutually inclined so as to impinge with one another in the atmosphere, at least one of the fluid jets being a jet of liquid extinguishant which is atomised by the impingement into a spray of drops.

14. A nozzle according to claim 13, in which the other jet is a jet of the same liquid.

15. A nozzle according to claim 13, in which the other jet is a gas jet.

16. A nozzle according to claim 15, in which the gas is air, nitrogen or other non-flammable gas.

17. A spray nozzle for fire extinguishing purposes. comprising a body portion formed with a plurality of first outlets for respectively emitting first fluid jets into the ambient atmosphere, a plurality of second outlets for respectively emitting second fluid jets into the atmosphere, the first outlets being positioned to direct the first jets parallel to each other and mutually spaced apart and the second outlets being positioned to direct the second jets in directions inclined to the first jets, each second jet being positioned to intersect with a respective one of the first jets so as to impinge with it in the atmosphere, at least one of each pair of intersecting jets being a jet of liquid extinguishant which is atomised by the impingement into a spray of drops.

18. A nozzle according to claim 17, in which the first outlets are spaced apart around a first circle and the first jets are parallel to the axis through the circle and the second outlets are spaced apart around a second circle concentric with the first circle and the second jets are inclined with respect to the axes of the circles.

19. A nozzle according to claim 18, in which the body portion comprises wall means defining two concentric chambers isolated from each other, one chamber being in communication with the first outlets and the other chamber being in communication with the second outlets, and supply means respectively connected to the two chambers for 16 supplying fluid thereto.

20. A nozzle according to any one of claims 17 to 19, in which at least the second jets are the jets of the liquid extinguishant.

21. A nozzle according to any one of claims 17 to 19, in which all the jets are jets of a liquid extinguishant.

22. A nozzle according to any one of claims 17 to 20, in which the jets which are not liquid jets are gas jets.

23. A nozzle according to claim 22, in which the gas is air, nitrogen or other non-flammable gas.

24. A nozzle according to any one of claims 13 to 23, in which the extinguishing liquid is water or a water-based liquid.

25. A method of fire extinguishing, substantially as described with reference to Figure 1 of the accompanying drawings.

26. A method of fire extinguishing, substantially as described with reference to Figure 2 of the accompanying drawings.

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27. A nozzle for f ire extinguishing purposes.. substantially as described with reference to Figure 1 of the accompanying drawings.

28. A spray nozzle for fire extinguishing purposes.. substantially as described with reference to Figure 2 of the accompanying drawings.