WO1992010238A1

WO1992010238A1 - Heat responsive valve and sprinkler

Info

Publication number: WO1992010238A1
Application number: PCT/GB1991/002115
Authority: WO
Inventors: David Nicholas Ball; Simon John Davies
Original assignee: Kidde Graviner Ltd
Current assignee: Kidde Graviner Ltd
Priority date: 1990-12-07
Filing date: 1991-11-29
Publication date: 1992-06-25
Anticipated expiration: 1993-06-07
Also published as: GB2250435A; GB9026628D0

Abstract

A nozzle for discharging liquid fire extinguishant has a temperature-responsive control element (29, 30) for controlling a flow of extinguishant from the nozzle in response to ambient temperature. The nozzle has a restrictor (28) for partially blocking an outlet orifice (22) of the nozzle which is operatively coupled to the temperature-responsive element (29, 30) which may be a gas-filled bellows (29) or a bi-metallic strip or disc (30). A valve for use with a nozzle for discharging liquid fire extinguishant has a coil spring (53) made from shape memory effect metal which controls the position of a valve member (45) in response to ambient temperature.

Description

Heat responsive valve and sprinkler.

BACKGROUND TO THE INVENTION This invention relates to a nozzle for discharging liquid fire extinguishant, especially, though not exclusively, a nozzle for discharging water. The invention also relates to a valve for use with a nozzle for discharging liquid fire extinguishant, such as water.

Such nozzles and valves have particular, though not exclusive, application in water spray systems installed, for example, in the passenger cabins of aircraft.

SUMMARY OF THE INVENTION The invention provides a nozzle, and a valve for use with a nozzle for discharging liquid fire extinguishant, incorporating means for controlling the flow of extinguishant in response to ambient temperature. The fire extinguishant is preferably water.

According to one aspect of the invention there is provided a valve for use with a nozzle for discharging liquid fire extinguishant, the valve comprising a valve body formed with a conduit having an inlet connectable to a source of the liquid fire extinguishant and an outlet connectable to the nozzle, a valve member displaceable within the conduit to control a flow of the extinguishant from the inlet to the outlet and temperature-responsive control means for controlling the position of the valve member in the conduit, wherein the control means includes a control element made from shape memory effect material which is so disposed externally of the conduit as to be responsive to the ambient temperature outside the valve body.

Preferably the control means comprises resilient means for biassing the valve member towards a fully closed position or a fully open position, and the control element is arranged to act in opposition to the resilient means.

Preferably the control element is also resilient, and the resilient means and the control element may comprise respective coil springs which act in opposed directions along a longitudinal axis of the valve member.

The temperature-responsive control means may comprise two or more temperature-responsive control elements made of the same shape memory effect material. By this means the temperature-responsive control means has a relatively low thermal mass and improved temperature responsivity. If the temperature-responsive control means comprises two or more temperature-responsive control elements made from different shape memory effect materials the valve is capable of controlling the flow of the extinguishant between several discrete flow rates.

The invention also provides a water spray system incorporating one or more nozzles and a valve as defined in accordance with the one aspect of the invention.

According to another aspect of the invention there is provided a nozzle for discharging liquid fire extinguishant incorporating temperature responsive means for controlling the flow of the extinguishant from the nozzle in response to the ambient temperature, wherein the liquid fire extinguishant is water and the temperature-responsive control means comprises a material that blocks an outlet orifice or orifices of the nozzle, the material being selected to become soluble in water, or to soften in the presence of water, at a predetermined ambient temperature whereby to permit a flow of the extinguishant from the nozzle.

Said material preferably consists of, or includes, poly(ethylene oxide) wax.

The control means may comprise more than one of said materials, each selected to become soluble in water, or to soften in the presence of water at a different respective predetermined ambient temperature whereby to vary the flow rate of extinguishant from the nozzle in dependence on the ambient temperature.

According to yet another aspect of the invention, there is provided a nozzle for discharging liquid fire extinguishant incorporating temperature responsive means for controlling the flow of the extinguishant from the nozzle in response to ambient temperature, wherein the temperature responsive control means comprises two or more different materials that block respective outlet orifices of the nozzle, each material being selected to melt at a respective predetermined ambient temperature whereby to vary the flow rate of extinguishant from the nozzle as a function of ambient temperature.

Said materials may be waxes such as saturated paraffinic hydrocarbon waxes.

Such temperature-responsive control means as employ materials which are soluble, or softenable in water or which melt at predetermined temperatures suffer from the drawback that their operation is irreversible; that is to say, the flow of extinguishant cannot be reduced or terminated in response to a subsequent fall of ambient temperature.

However, the invention also provides nozzles having temperature-responsive control means arranged to vary the flow of extinguishant over a range of flow rate.

Accordingly, the invention further provides a nozzle for discharging liquid fire extinguishant comprising a restrictor for blocking an outlet orifice of the nozzle and being displaceable relative to the orifice whereby to regulate a flow of the extinguishant from the orifice, and temperature-responsive control means arranged to displace the restrictor relative to the orifice in dependence on the ambient temperature.

A nozzle such as this can discharge the extinguishant at a relatively high flow rate when the ambient temperature is relatively high, as when a fire in the vicinity of the nozzle is at its height, and the flow rate can be reduced, possibly to zero, in response to a fall of ambient temperature that occurs when the fire is brought under control. This arrangement enables efficient utilisation of the available extinguishant and is especially beneficial if the supply of extinguishant is limited, as in the case, for example, of an aircraft water supply system having an on-board water supply vessel.

The temperature-responsive control means may be effective to regulate the flow of extinguishant over a continuous range of flow rate and, to that end, the control means may be a gas-filled bellows operatively coupled to the restrictor or one or more bimetallic elements operatively coupled to the restrictor.

Alternatively, the temperature-responsive control means may be effective to vary the flow of extinguishant between two or more discrete flow rates - for example, a high flow rate and a low flow rate or a high flow rate and zero.

In this case the temperature-responsive control means may comprise one or more bi-metallic elements having different temperature responses operatively coupled to the restrictor or one or more elements made from different shape memory effect materials operatively coupled to the restrictor.

The temperature-responsive control means may be located within the body of the nozzle. However, it is preferred to locate the temperature-responsive control means outside the nozzle body so as to be in more intimate contact with the ambient air. The invention further provides a water spray system incorporating one or more nozzles as defined herein, and particularly a water spray system for use in an aircraft.

DESCRIPTION OF THE DRAWINGS Embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a longitudinal cross-section view through a water discharge nozzle in accordance with the invention;

Figure 2 shows a longitudinal cross-sectional view through another water discharge nozzle according to the invention;

Figure 3 shows a longitudinal cross-sectional view through a yet further example of a water discharge nozzle according to the invention, and

Figure 4 shows a longitudinal cross-sectional view through a valve for use in a water discharge nozzle.

DESCRIPTION OF PREFERRED EMBODIMENTS Figure 1 shows a water discharge nozzle having a simple open/closed operation. The nozzle comprises a cylindrical housing 10 connected to a water supply inlet 11 and having an end wall 12 formed with several outlet orifices 13. In the closed condition of the nozzle each outlet orifice is blocked by a solid mass 14 of material that prevents water from being discharged by the nozzle. The material blocking the outlet orifices 13 is chosen to have a relatively low melting temperature (typically in the range 40 - 80 C) and is preferably a wax i.e. a solid having a relatively low melting temperature typically comprising saturated paraffinic hydrocarbons.

In the event of a fire, the ambient temperature will rise causing the wax to melt and the nozzle to assume the open condition thereby allowing water to be discharged. More than one type of wax each having a different melting temperature could be used to block the several orifices of a single nozzle so that the flow rate is progressively increased if the temperature continues to rise. It has been found that the water discharging from the nozzle tends to cool the wax causing the wax to resolidify before it has completely cleared the outlet orifices 13. It is preferable to use a wax that is soluble in water, or a wax that softens in the presence of water at a critical temperature. Examples of such waxes include those based on poly(ethylene oxide) . Again, more than one type of wax, soluble or softenable at different critical temperatures, could be used to block the several outlet orifices of a single nozzle whereby progressively to increase the flow rate should the temperature continue to rise.

The nozzles described with reference to Figure 1 have the disadvantage that their operation is irreversible - the flow rate cannot be reduced or terminated in response to a subsequent fall of ambient temperature, and this could be disadvantageous in circumstances where the supply of extinguishant is limited, as in the case of an on-board supply in an aircraft water spray system.

Figure 2 shows an alternative form of nozzle that enables the flow of water to be varied over a continuous range of flow rate in response to changes of ambient temperature.

Referring to the drawing, the nozzle comprises a nozzle body 20 having an inlet 21 and an outlet orifice 22 provided in an end wall 23 of the nozzle body.

In use, water flows around a cylindrical valve member 24 and exits the outlet orifice as a spray. The valve member has a helical, ribbed formation on its exterior surface for inducing swirling as the water approaches the outlet orifice, creating a spray in the form of a hollow cone. The valve member has an axial shaft 25 located in a cylindrical socket 26 of a circumferentially-apertured support member 27 and is also formed with^' a restrictor in the form of a pip 28 which is arranged to be in axial alignment with the outlet orifice so as to be capable of at least partially blocking the outlet orifice.

The nozzle has a temperature responsive element in the form of a sealed, gas-filled bellows 29 which is mounted on the support member 27 and connected to the support shaft of the valve member, as shown. In operation of the nozzle, the bellows can expand and contract (as indicated by arrow A) in response to a respective rise and fall of ambient temperature whereby to vary the axial position of the restrictor in the outlet nozzle and exercise control over the flow of water through the nozzle. If desired, the pip 28 could be suitably profiled to obtain a desired variation of flow rate as a function of the ambient temperature.

In the embodiment of Figure 3, the temperature-responsive element is a bi-metallic element, such as a bi-metallic strip or disc, that can switch between two stable positions at a predetermined ambient temperature - a first position I (shown in solid outline) and a second position II (shown in broken outline) . This causes a corresponding change in the axial position of the restrictor enabling the nozzle to switch between a high flow rate (corresponding to position I) and zero or a low flow rate (corresponding to position II) . Instead of using a bimetallic element, a temperature-responsive element such as a strip, rod or spring made from shape memory effect material, such as Ni-Ti alloy could alternatively be used. The shear modulus of a shape memory effect material increases sharply at a critical temperature thereby exerting a biassing force on the restrictor and causing its axial displacement.

In order to provide a greater variety of different flow rates, two or more bi-metallic elements which switch at different predetermined tempratures could be used. Similarly, temperature responsive elements made from different shape memory effect materials, having different critical temperatures could be used. The temperature responsivity of the element or elements is improved if they have relatively high surface area-to-volume ratio, and elements in the form of flat-sided strips are preferred. The temperature responsivity can also be improved by decreasing the thermal mass of the arrangement and this can be achieved using multiple temperature- responsive elements made from the same or different materials. A bi-metallic temperature-responsive element or several such elements made from the same or different materials could be so arranged as to provide a continuous displacement of the restrictor as a function of ambient temperature giving a continuous variation of flow rate.

It may be advantageous in some circumstances to configure such a nozzle so that the temperature-responsive element is located outside the nozzle body so that it is in better thermal contact with the ambient air and is less affected by the presence of water within the nozzle.

Figure 4 shows a temperature-responsive valve 40 for controlling a supply of water to one or more water spray nozzles. As will be described, the valve 40 incorporates a temperature-responsive control element made from shape memory effect metal enabling the valve to control the discharge of water from the nozzle or nozzles in response to changes of ambient temperature.

The valve comprises a valve body 41 having a cylindrical bore 42 defining a conduit between an inlet 43, connected to a supply of water, and an outlet 44 connected to the or each nozzle. The valve has a spool-type valve member 45 displaceable axially by a temperature-responsive control arrangement, referenced generally at 46, located externally of the valve body. The valve body 45 has an axial rod 47 which extends through an opening 48 in an end wall 49 of the valve body. The rod 46 is formed with a flange 50 which serves as an end stop limiting axial displacement of the valve member (to the right in the drawing) defining the fully-closed position of the valve, the position illustrated. The axial rod has a second flange 51 positioned externally of the valve body which is acted upon by two coil springs 52,53. Coil spring 52 bears against end wall 49 and flange 51 biassing the valve member to the right, towards the illustrated, fully-closed position, whereas the other spring, referenced 53, bears against flange 51 and an abutment 54 integral with the valve body 41, and acts in opposition to the coil spring 51. Spring 53 is made from shape memory effect material, such as Ti-Ni alloy and constitutes the afore-mentioned temperature-responsive control element of the valve. If the temperature of the surrounding air exceeds a critical value, the shear modulus of the shape memory effect material increases sharply, causing the force exerted by spring 53 to exceed that of spring 52 thereby to displace the valve member 45 to the left in the drawing, causing the valve to open.

By positioning the temperature-responsive coil spring 53 externally of the valve body it is in better thermal contact with the surrounding air and is less affected by the presence of the water passing through the valve body.

As the surrounding air is cooled by the water discharging from the nozzles, the ambient temperature falls below the critical temperature of the shape memory effect material. Thus, the force exerted by spring 53 is reduced enabling spring 52 to return the valve member 45 to the fully closed position thereby closing the valve and cutting off the supply of water to the spray nozzles.

It will be appreciated that the temperature-responsive control element need not necessarily have the form of a spring. Alternatively, a rod or strip made from shape effect memory material could be used. A flat-sided strip is preferred because it has a relatively large surface area and is more rapidly responsive to ambient temperature. The temperature-responsiveness could be increased further by the use of several such strips made from the same shape effect memory material.

In an alternative arrangement several strips or rods or springs made from shape effect memory materials having different critical temperatures could be used. By this means, the valve member can be displaced to different axial positions whereby to vary the flow of water between two or more discrete flow rates.

Instead of using one or more elements made from shape effect memory material it would alternatively be possible to use one or more bi-metallic strips.

In the case of a water spray system for aircraft, it is known that the effectiveness of the spray is to wet combustible material adjacent to where the fire is gaining ingress thereby to prevent the spread of an external fire into the cabin or to control further spread of a fire which is already present in the cabin.

It will be appreciated that the valve and discharge nozzles described with reference to the drawings are merely exemplary of the valve and nozzle systems that could be devised in accordance with the present invention.

Claims

1. A valve for use with a nozzle for discharging liquid fire extinguishant, the valve comprising a valve body formed with a conduit having an inlet connectable to a source of the liquid fire extinguishant and an outlet connectable to the nozzle, a valve member displaceable within the conduit to control a flow of the extinguishant from the inlet to the outlet and temperature-responsive control means for controlling the position of the valve member in the conduit, wherein the control means includes a control element made from shape memory effect material which is so disposed externally of the conduit as to be responsive to the ambient temperature outside the valve body.

2. A valve as claimed in claim 1, wherein the control means comprises resilient means for biassing the valve member towards a fully closed position or a fully open position, and the control element is arranged to act in opposition to the resilient means.

3. A valve as claimed in claim 2, wherein the control element is resilient.

4. A valve as claimed in claim 2 or claim 3, wherein the resilient means and the control element comprises respective coil springs which act in opposed directions along a longitudinal axis of the valve member.

5. A valve as claimed in any one of claims 1 to 4, wherein the shape memory effect material is a Ti-Ni alloy.

6. A valve as claimed in any one of claims 1 to 4, wherein the temperature-responsive control means comprises two or more temperature-responsive control elements made from the same shape memory effect material.

7. A valve as claimed in any one of claims 1 to 4, wherein the temperature-responsive control means comprises two or more temperature responsive control elements made from different shape memory effect materials.

8. A water spray system incorporating one or more nozzles and a valve as claimed in any one of claims 1 to 7 for controlling a supply of water to at least one of said nozzles.

9. A water spray system as claimed in claim 8, for use in an aircraft.

10. A nozzle for discharging liquid fire extinguishant incorporating temperature responsive means for controlling the flow of the extinguishant from the nozzle in response to the ambient temperature, wherein the liquid fire extinguishant is water and the temperature-responsive control means comprises a material that blocks an outlet orifice or orifices of the nozzle, the material being selected to become soluble in water, or to soften in the presence of water, at a predetermined ambient temperature whereby to permit a flow of the extinguishant from the nozzle.

11. A nozzle as claimed in claim 10, wherein said material consists of or includes poly(ethylene oxide) wax.

12. A nozzle as claimed in claim 10 or claim 11, wherein the control means comprises more than one of said materials, each selected to become soluble in water, or to soften in the presence of water at a different respective predetermined ambient temperature whereby to vary the flow rate of extinguishant from the nozzle in dependence on the ambient temperature.

13. A nozzle for discharging liquid fire extinguishant incorporating temperature responsive means for controlling the flow of the extinguishant from the nozzle in response to ambient temperature, wherein the temperature responsive control means comprises two or more different materials that block respective outlet orifices of the nozzle, each material being selected to melt at a respective predetermined ambient temperature whereby to vary the flow rate of extinguishant from the nozzle as a function of ambient temperature.

14. A nozzle as claimed in claim 13, wherein said materials are waxes such as saturated paraffinic hydrocarbon waxes.

15. A nozzle for discharging liquid fire extinguishant comprising a restrictor for blocking an outlet orifice of the nozzle and being displaceable relative to the orifice whereby to regulate a flow of the extinguishant from the orifice, and temperature-responsive control means arranged to displace the restrictor relative to the orifice in dependence on the ambient temperature.

16. A nozzle as claimed in claim 15, wherein the temperature-responsive control means is effective to regulate the flow of extinguishant from the nozzle over a range of flow rate.

17. A nozzle as claimed in claim 16, wherein the temperature-responsive control means is effective to regulate the flow of extinguishant from the nozzle over a continuous range of flow rate.

18. A nozzle as claimed in claim 17, wherein the temperature-responsive control means is a gas-filled bellows operatively coupled to the restrictor.

19. A nozzle as claimed in claim 17, wherein the temperature-responsive control means comprises a bimetallic element operatively coupled to the restrictor.

20. A nozzle as claimed in claim 17, wherein the temperature-responsive control means comprises two or more bimetallic elements operatively coupled to the restrictor.

21. A nozzle as claimed in claim 14, wherein the temperature-responsive control means is effective to vary the flow of extinguishant between two or more discrete flow rates.

22. A nozzle as claimed in claim 18, wherein the temperature-responsive control means comprises one or more bimetallic elements having different temperature responses operatively coupled to the restrictor.

23. A nozzle as claimed in claim 16 or claim 21, wherein the temperature-responsive member comprises one or more elements made from different shape memory effect materials operatively coupled to the restrictor.

24. A nozzle as claimed in any one of claims 15 to 23, wherein the temperature-responsive control means is located external to the nozzle body.

25. A nozzle as claimed in any one of claims 13 to 21 for discharging water.

26. A water spray system incorporating one or more nozzles as claimed in any one of claims 10 to 25.

27. A water spray system as claimed in claim 26 for use in an aircraft.