NOZZLE ASSEMBLY

Abstract: A nozzle assembly for connection to a pressurised source of fire extinguishant comprises a heat collector (6) normally secured to the exterior of an extension wall (8) of a nozzle body (1) by an annular bead of low melting point alloy (9) which is adapted to liquefy at a predetermined temperature, the heat collector (6) normally holding a plug (10) against part of the nozzle body (1) to close a discharge opening for extinguishant and prevent discharge therethrough, the heat collector (6) and plug (1) being released from the nozzle body (1), so as to allow extinguishant discharge, upon melting of the alloy (9) by conduction of heat from the heat collector (6), the plug providing a sliding seal against the nozzle body until the heat collector is completely detached therefrom.

Description: NOZZLE ASSEMBLY The present invention relates to a nozzle assembly for fire protection apparatus and more particularly to a nozzle assembly adapted for the automatic local discharge of fire extinguishant from a pressurised source thereof upon the detection of an excessive temperature condition in the vicinity of the assembly. Fire protection apparatus is known, e.g. from DE-A-4000010, comprising a series of discharge nozzles connected to a pressurised container of fire extinguishant, the outlet of each nozzle being normally sealed by a plug of low melting point alloy, such as solder. The intention is that in the event of a fire in the vicinity of the apparatus the alloy will be melted/liquified by the heat of the fire, thereby opening up the nozzles to permit automatic discharge of the extinguishant. A disadvantage of such an arrangement, however, particularly in the case of liquid fire extinguishants, is that as soon as sufficient of the alloy has melted to create a flow path through the nozzle, the flowing extinguishant will cool the alloy and may prevent it from further melting, so that the nozzle remains only partially open. From DE-A-3337532, another arrangement is known which also depends on the melting of a low melting point alloy to permit automatic discharge of a pressurised fire extinguishant. In this case the nozzle terminates in a cylindrical or flared outlet within which a cap of complementary form is normally held. The cap is secured to the nozzle by a ring of alloy at its outer end and at its inner end the cap holds a sealing disc against an annular seat formed by a step in the nozzle wall, against the applied pressure of the extinguishant. Again the intention is that the alloy will be melted by the heat of a fire, in this case to loosen the cap from the nozzle, the cap and seal then being ejected by the pressure of the extinguishant to open up the whole of the nozzle to flow. This arrangement may also suffer from the problem of premature alloy cooling, however, that is to say, as soon as the alloy has melted sufficiently to permit any movement of the cap relative to the nozzle the sealing action will be lost and extinguishant will be allowed to flow between the cap and the surrounding nozzle wall. This may lead to cooling of the alloy to the extent that the intended ejection of the cap is prevented. An object of the present invention is to provide a nozzle assembly in which the above-mentioned drawbacks of the prior art can be reduced or eliminated. According to one aspect of the present invention there is provided a nozzle assembly for connection to a pressurised source of fire extinguishant, the assembly comprising a heat collecting member normally secured to a nozzle structure by a low melting point alloy adapted to liquefy at a predetermined temperature, the heat collecting member normally retaining a sealing member to prevent the discharge of extinguishant through a nozzle of the nozzle structure, the heat collecting and sealing members being releasable from the nozzle structure upon liquefication of the alloy by the conduction of heat from the heat collecting member, and the sealing member being adapted to form a sliding seal against the nozzle structure until a predetermined degree of relative movement has occurred between the heat collecting member and the nozzle structure. In this way it can be ensured that there is no discharge of extinguishant which could reach the area of the alloy until the heat collector has become completely detached from the nozzle structure, and hence no danger of the nozzle only partially opening. In a preferred embodiment of the invention the nozzle structure comprises a discharge opening spaced inwardly from a cylindrical wall. Desirably the heat collecting member has a dished portion which normally fits over an outer end of said cylindrical wall and is secured externally to said wall by a ring of low melting point alloy between respective circumjacent faces of the dished portion and said wall. Conveniently the sealing member is normally disposed interiorly of, and in sliding sealing relationship with, said cylindrical wall, between the discharge opening and the heat collecting member. According to a second aspect of the present invention, there is provided fire protection apparatus comprising a pressurised source of fire extinguishant connected to one or more nozzle assemblies as defined above. The invention will now be described, by way of example, with reference to the accompanying drawing, the single figure of which is a cross- sectional view of a nozzle assembly of the invention. Referring to the drawing, there is shown a nozzle assembly comprising a main body 1 , for example of brass, having a central passage 2 and a threaded inlet end 3 for connection to pipework leading from a pressurised source of fire extinguishant. The illustrated assembly may be one of a plurality of similar assemblies connected to a common extinguishant source, the type of extinguishant itself being selected with regard to the type of risk to be protected. In principle nozzles according to the invention may be employed with any conventional media, whether liquid, gaseous or powder, although it is particularly in connection with the use of liquid extinguishants that the advantage of the invention are exhibited. The illustrated assembly may in particular be used with foam solutions or liquefied gas extinguishants for the protection of deep fat fryers and cooking ranges, engine compartments or other enclosed fire risks. Formed integrally with the body 1 at the outlet end of the passage 2 is a nozzle 4, which constitutes a discharge opening for extinguishant in use of the device. In the illustrated embodiment an (optional) insert 5 is mounted in the passage 2 upstream of the nozzle 4 and defines a helical channel to impart a swirling motion to the discharging extinguishant, in use. The next major component of the assembly is a generally frusto- conical, heat collector 6 of copper alloy or other heat conductive metal. This member has a dished central portion 7 which fits on and over a free end of a cylindrical extension wall 8 formed integrally with the body 1 , the wall surrounding and extending forwardly of the nozzle 4. The heat collector 6 is secured to the body 1 by an annular bead of low melting point alloy 9 between the respective circumjacent faces of its dished portion 7 and the extension wall 8. In one embodiment the low melting point alloy could be solder. The final component of the assembly is a moulded plastics sealing member or plug 10, which is disposed in the space within the extension wall 8 between the heat collector 6 and nozzle 4, and carries an 'O' ring 1 1 to form a sliding seal against the internal face of the extension wall 8. The plug 10 is sized so that with the collector 6 secured to the wall 8, the portion 7 of the collector engages an outer end of the plug to hold the plug onto the nozzle which is thus closed off. In the illustrated inactive state of the assembly, the plug 10 is retained by the heat collector 6 against the applied pressure of the extinguishant in passage 2 and closes off the nozzle 4 as described. In use, the assembly will be disposed with the heat collector 6 oriented towards the risk to be protected, so that in the event of fire or other excessive temperature condition in its vicinity, heat will be conducted from collector 6 to the alloy ring 9. The low melting point alloy is selected to liquefy at a temperature indicative of fire or incipient fire in the protected risk. In any particular installation the chosen temperature will depend on the nature of the risk and of the siting of the assembly, but will typically be within the range of 65-200°C. When the specified temperature is reached the alloy begins to liquefy, thereby loosening the heat collector 6 from the body 1 , and the tendency of the extinguishant pressure in passage 2 is to eject the plug 10 and thus collector 6 from the body, thereby opening up the nozzle 4 to discharge the extinguishant over the risk. As will be appreciated from the drawing, however, no extinguishant can pass the 'O' ring 1 1 until the latter reaches the end of the cylindrical extension wall 8, at which point the collector 6 will be physically clear of the body 1. Consequently there is no danger of the alloy 9 being cooled by the extinguishant in the course of ejecting the collector such as could prevent complete ejection. Full and rapid opening of the nozzle is thereby assured.

Claims: CLAIMS 1. A nozzle assembly for connection to a pressurised source of fire extinguishant, the assembly comprising a heat collecting member normally secured to a nozzle structure by a low melting point alloy adapted to liquefy at a predetermined temperature, the heat collecting member normally retaining a sealing member to prevent the discharge of extinguishant through a nozzle of the nozzle structure, the heat collecting and sealing members being releasable from the nozzle structure upon liquefication of the low melting point alloy by the conduction of heat from the heat collecting member, and the sealing member being adapted to form a sliding seal against the nozzle structure until a predetermined degree of relative movement has occurred between the heat collecting member and the nozzle structure. 2. An assembly as claimed in Claim 1 , wherein the nozzle structure comprises a discharge opening spaced inwardly from a cylindrical wall. 3. An assembly as claimed in Claim 2, wherein said cylindrical wall surrounds and extends forwardly of said discharge opening. 4. An assembly as claimed in Claim 2 or Claim 3, wherein the heat collecting member has a dished portion which normally fits over an outer end of said cylindrical wall and is secured externally to said wall by said alloy. 5. An assembly as claimed in Claim 4, wherein said securement of said dished portion of the heat collecting member is by a ring of said alloy between respective circumjacent faces of said dished portion and said wall. 6. An assembly as claimed in any one of Claims 2 to 5, wherein the sealing member is normally disposed interiorly of, and in sliding sealing relationship with, said cylindrical wall, between the discharge opening and the heat collecting member. 7. An assembly as claimed in Claim 6, wherein the sealing member is in the form of a plug, an inner surface of which is held against the nozzle structure, to prevent said discharge of extinguishant, by the engagement of said heat collecting member against an outer surface of the plug. 8. An assembly as claimed in Claim 4, wherein the dished portion of said heat collecting member engages against an outer surface of said sealing member to hold an inner surface thereof against the nozzle structure to close said discharge opening. 9. An assembly as claimed in any one of Claims 2 to 8, wherein an external surface of said sealing member has an annular groove therein, and O-ring seal received in said groove slidingly sealing between said sealing member and an interior surface of said cylindrical wall upon sliding of the sealing member through said space inside said cylindrical wall as a result of melting/liquification of said alloy, in use. 10. An assembly as claimed in any one of the preceding claims, wherein the heat collecting member has a front frusto-conical collection portion. 1 1. An assembly as claimed in Claim 10, wherein said heat collecting portion is made of copper alloy. 12. An assembly as claimed in any one of the preceding claims, wherein the sealing member is made of plastics material. 13. An assembly as claimed in any one of the preceding claims, wherein the nozzle is at one end of a passage for extinguishant flow, there being an insert in said passage to impart a swirling motion to discharging extinguishant, in use. 14. An assembly as claimed in Claim 13, wherein the insert defines a helical channel to impart said swirling motion. 15. An assembly as claimed in any one of the preceding claims, wherein the low melting point alloy is solder. 16. Fire protection apparatus comprising a pressurised source of fire extinguishant connected to one or more nozzle assemblies as claimed in any one of the preceding claims.

Inventors: EVANS JOHN LAWRENCE, PATEL DEVANG, EVANS, JOHN, LAWRENCE, PATEL, DEVANG
Applicants: CHUBB FIRE LTD, EVANS JOHN LAWRENCE, PATEL DEVANG, CHUBB FIRE LIMITED, EVANS, JOHN, LAWRENCE, PATEL, DEVANG
Application year: 1998
Main classification: A62C37
IPC codes: A62C37