Sprinkler outlet closure device

Abstract

 A sprinkler outlet closure assembly comprises a closure member (17) held in a closing position by a lever system which divides the closure load between a fallible element such as a glass capsule (30) which shatters on heating of liquid therein, and a frame of the device. The fallible device may be or incorporate a fusible element.

Description

[0001] This invention relates to an improved sprinkler outlet closure device.

[0002] A major class of fire extinguishing sprinkler systems, comprises those systems which respond automatically to the occurrence of a fire in the room or space in which the sprinkler is located, to operate the sprinkler, instead of being centrally controlled. Detection triggers include smoke detectors, radiant heat sensors, and the incorporation of a fusible element in the nozzle, which operates to allow the nozzle to open.

[0003] One particular form of automatic sprinkler uses a glass capsule containing a thermally responsive liquid. Closure load on a closure member is exerted through the capsule, retaining a sprinkler nozzle closed against the pressure of water in the system. When a fire occurs in the space wherein the nozzle is located, the liquid in the capsule expands, and thereby shatters the capsule. This releases the nozzle closure member, and water is allowed to flow under pressure from the nozzle. The mechanical strength of the capsule places an upper limit of the closure member, and thus on the line pressure of the water in the system or diameter of orifice of the nozzle device. It is desirable to make the capsule as small and as thin-walled as is compatible with sustaining the closing force on the nozzle closure member by means of the capsule. The scope for such economies is however limited by the demand for the capsule to sustain the full closure force.

[0004] The use of frangible capsules in a linkage serving to hold a sprinkler valve in the closed position is known from e. g. GB 346, 984, wherein such a capsule is used as one link in a lever assembly holding an outlet stopper closed against the water pressure, so that when the capsule is broken by expansion of the liquid in the capsule, the lever assembly collapses allowing the stopper to be pushed out of the outlet, opening the sprinkler valve.

[0005] In EP-A-558, 103 (=US 4, 930, 578), there are described embodiments of sprinkler outlets each incorporating a frangible capsule in parallel with a strut, incorporating a mechanical advantage so that the strut bears the greater part of the load imposed by water pressure on the linkage. One embodiment described therein comprises a capsule mounted on the axes of the outlet, supported on an end of lever which is pivoted close to a side frame member, and loaded in the water pressure direction by contact with an edge of a closure stopper, close to the pivot point, so that a substantial mechanical advantage is obtained, enabling the fragile capsule to sustain the load. The embodiment has disadvantages due to the use of only one lever, which is relatively unstable and vulnerable to side load, such as accidental knocks, and poor transit handling. The support around the bulb is not symmetrical, and thus the tail of the bulb may be subjected to breakage which may cause drainage of the bulb and subsequent failure of the sprinkler to operate. This arrangement also tends to magnify the effects of pressure surges or vibrations in the water supply, due for example to air locks and cavitation.

[0006] An object of the invention is to provide a sprinkler outlet closure device which is released by breaking of a capsule due to heating of a thermally responsive liquid in the capsule, wherein the device is constructed in such way that the capsule does not sustain the full closure force acting on the nozzle closure member, yet remains essential to maintenance of the closure force so that the closure member will be released on shattering of the capsule.

[0007] The invention provides a sprinkler outlet closure device comprising a nozzle closure member a fallible member designed to fail above a threshold temperature being positioned to retain the closure member in a nozzle closing position, the capsule having abutment means, and lever means bearing on said abutment means of the capsule, said lever having means providing a fulcrum arranged to bear on said nozzle closure member, and serving to divide the load acting through the capsule, in proportion to the mechanical advantage of said lever means.

[0008] The fallible member is preferably a capsule containing thermally responsive liquid designed to shatter the capsule on heating of the liquid.

[0009] The nozzle closure member may incorporate a belleville spring, the rim of which is pressed against a bearing surface provided in the nozzle, and a substantially bowl shaped member, having means for locating in the central aperture of the belleville spring and abutting with the rim of the said aperture, and a rim, directed away from the belleville spring, which is adapted to serve as said fulcrum means.

[0010] In a preferred embodiment, a number of e. g. diametrically opposed levers may be balanced on the said rim, and extend to the centre of the member. The other ends of the levers may extend outwardly to engage with side frame members. The inner ends of the levers may be shaped to define an aperture between said inner ends, into which may be inserted either end portion of a hollow glass capsule, of a generally cylindrical shape. The reducing diameter end portion effectively define shoulders on the main part of the capsule, which abut on the ends of the levers, about the aperture defined by their ends. These shoulders provide abutment means.

[0011] The other end of the capsule may be located against an adjustment screw or other means in an aperture in a frame part, the screw or the like being displaceable to adjust the force exerted through the capsule onto the belleville spring.

[0012] The capsule may contain a thermally responsive liquid, which in heating to a predetermined temperature as for example by an outbreak of fire, will expand, and shatter the capsule, thereby releasing the load allowing the line pressure of water to displace the closure, and be released to operate the sprinkler.

[0013] In a further embodiment of the invention the nozzle closure member may be modified in that the capsule is replaced by a link or other member comprising or including a fusible material such as solder, whereby on exposure to hot gases the link or member will fail mechanically in order to release the sprinkler valve.

[0014] The link may comprise two or more pieces of rigid metallic material, such as copper, which are connected end to end or face to face by the fusible material. When the fusible material is melted by the increase in temperature occurring in a fire, the link collapses.

[0015] The link may be comprised by a fusible material such as a synthetic plastic material which is sufficiently rigid to be load bearing, but softens when the temperature rises beyond a threshold to no longer be load bearing, and cease to function as a load bearing member so that the sprinkler valve is released.

[0016] The invention will now be further described by way of example with reference to one preferred embodiment of the invention, with reference to the accompanying drawings, wherein:-

Fig. 1

is a diagrammatic cross-sectional view of a sprinkler nozzle incorporating a closure device according to the invention,

Fig. 2

is a diagram showing how the forces are divided by use of the device according to the invention,

Fig. 3

is a diagram of a second embodiment of sprinkler nozzle incorporating a closure device to the invention,

Fig. 4

is a perspective view of a third embodiment of sprinkler nozzle incorporating a closure device to the invention; and

Fig. 5

is a diagram similar to Fig 1 of a fourth embodiment of sprinkler nozzle incorporating a closure device according to the invention.

[0017] Fig. 1 shows in axial cross-section, a first example of sprinkler nozzle, including a closure device according to the invention. The nozzle comprises a threaded boss 10, for insertion into a counter-threaded connector and fitted to a flange 11 which is faceted for engagement by a fixing tool. A flat sealing face 12 is disposed about the end of the passage 13 through the boss 10. The outer rim 14 of a belleville washer 15 rests on this face 12. A bowl shaped member 16 has a central protrusion 17 which enters the central aperture of the washer 15, and seals against the inner edge of the belleville washer. The bowl-shaped member 16 also has a complete or partial peripheral rim or linear fulcrum edge, which may encompass location lugs which positively constrain the sideways position/location of the levers 25, 26 on the fulcrum edge 18, directed away from the washer 15. The flange 11 is connected to a pair of diametrically opposed arms 19, 20, which hold boss 21 in axial alignment with the passage 13. Boss 21 has an axially aligned bore 22 in which is received for example a tightening screw 23. A formed deflector disc 24, is secure to the boss, and may have an indented circumferential edge. Water from the nozzle will impinge on this, and be sprayed over a predetermined area.

[0018] A number of levers such as, 25, 26 are balanced in the rim or edge 18 of the bowl shaped member 16, and have their outer ends received in respective slots 27, 28, in respective arms 19, 20. The free ends of the lever extend radially inward to the axis of the nozzle, and are cut out to together define a aperture (not shown in Fig. 1).

[0019] The aperture receives a collar 32 which in turn receives a reduced diameter end portion 29 of glass capsule 30, which has shoulders 31 about the end portion 29, which rest on the ends of the levers 25, 26 and serve as abutments on the capsule.

[0020] The capsule 30 is generally cylindrical in configuration and contains a thermally responsive liquid, which on heating due to occurrence of a fire will expand and create pressure which will shatter the glass capsule as the cylindrical shape is optimised to resist externally applied longitudinal loads, but is also designed to fracture when subjected to a predetermined internally applied pressure. The capsule 30 extends to abut the inner end of adjusting screw 23 and levers 25 and 26 but also full sealing force is exerted on the for example belleville washer 15 to thereby maintain the nozzle valve closed against the water pressure acting on the upstream side of the valve. In this embodiment the collar 32 serves to seat the capsule 30 symmetrically in the levers and in other embodiments, the collar 32 may be dispensed with, and the capsule 30 may be fitted in either orientation. The collar protects fragile end portion or tail 29 of the capsule.

[0021] The dimensions of the rim or fulcrum edge 18 of the bowl shaped member 16, and the length of the levers 25, 26 is chosen in the preferred embodiments to give a mechanical advantage, so that unit axial force on the capsule exerted at the ends of the levers will produce a reactive force in the lower part of the arms 19, 20. A counter force will be directed through the member 16 to act on the sealing member (the e. g. belleville washer 15) to produce the required sealing force, which should be greater than the force generated by the water pressure.

[0022] If and when the capsule shatters, due to heating by a fire, the force transmission linkage will break down, and the closure force will be released, allowing water to escape from the nozzle.

[0023] Fig. 2 shows the distribution of loading forces achieved by the device according to the present invention shown in Fig. 1. The pressure P of water in the supply line to sprinkler head exerts a force on the member 16, which is transmitted via rim or edge 18 to the levers 25, 26. A counter force resistance is exerted via the capsule 30 and the lower portions of side members 19, 20 (at slots 27 and 28) so that the levers 25, 26 each act as if pivoted on the rim or edge 18, and with rim or edge 18 significantly closer to the sides than to the axis, produce a mechanical advantage 'A'/'B' which is favourable to the capsule so that the major part of the resistance force is exerted via the lower portions of the side frames 19, 20 and a minor proportion by the capsule. The advantage may in practice be in the range 3:1 to 8:1 for example depending on the dimensions, and the number of levers employed.

[0024] Fig. 3 illustrates a modified embodiment of sprinkler outlet closure according to the invention, to allow the use of capsules of short length in standard or large sprinkler heads or standard length capsules in large sprinkler heads.

[0025] The embodiment differs from the first embodiment primarily in that it employs cranked levers e. g. via a collar 132, in engagement with the ends of levers 125, 126 and the other ends of which are received in slots on the side frame members 119, 120, and have level parts 125a which rest on the opposite sides of a rim 118 of a valve stopper 117. The levers having respective sloped parts 125b, 126b, to thereby retain the end of the capsule at a location spaced from the plane of the rim or edge 118 so that a short capsule and retainer may be used when appropriate.

[0026] Fig. 4 is a perspective view of a further embodiment of sprinkler outlet closure according to the inventions. This includes a threaded boss 210, a flange 211, and side arms 219, 220 which carry for example a notched deflector disc 224. A boss 223 extends up from the junction of the side arms 219, 220 and has for example an axial screw 222 which bears on one end of a capsule 230. The other end of capsule 230 has an end section which is received in a collar 232 which is carried by meeting ends of a number (for example two) radially extending levers 225, 226. These levers 225, 226 are pivoted on complete or partial annular rim edge 218 of a member not shown which is similar to member 17 of Fig. 1 and is likewise assembled to a belleville spring also not shown. The radially outer ends of the levers 225, 226 are received in slots 227, 228 in stub members 214, 215.

[0027] The operation of the outlet is as described for Fig. 1 above, i.e. when fire occurs, the capsule 230 is shattered by expansion of liquid therein, this destroys the linkage holding the plug in place, and the water is released. The outlet differs from Fig. 1 in that instead of the levers being received in the arms 220, 219 they are received in the stubs 214, 215. This reduces the load to be borne by the arms so that these can be made to be more slender than in known sprinklers.

[0028] In the closure device shown in Fig. 5 a boss 301 is provided for screw fitting into a sprinkler nozzle outlet. A conical plug or valve member 302 is used to close a passage 303 in the boss 301 and carries a circular member 304 with a raised rim 305 which provides a fulcrum for two lever members 306, 307.

[0029] One end of each lever member 306, 307 is engaged by a projection 308, 309 in the inner side of a respective limb 310, 311 of a frame 312. The other end of each lever 306, 307 engages an element 313 which comprises two, three or more pieces of rigid material connected by a fusible material such as solder, which is solid at room temperature, but softens or liquefies at higher temperatures so that the element 313 fails mechanically when the element 313 is exposed to high temperatures such as these of combustion gases in a fire situation.

[0030] The element 313 may alternatively comprise a material which softens at high temperatures whilst being capable of load bearing at normal room temperatures, such as a suitable synthetic plastics material, or appropriate metal alloy.

[0031] Sprinkler outlet devices according to the invention, such as those herein before described, have important advantages over outlet devices according to the prior art.

[0032] The arrangement of parts is compact, with a small low-cost mechanism and requires little space but it can be adapted for small and large sprinklers, and/or for the use of large or small capsules.

[0033] The device is capable of being designed as an aesthetically pleasing article, and due to the contained housing of its working parts it is inherently protected from shock and also from interference and tampering. The mechanism is also inherently robust and effectively self locking. The lever arms are locked into each other and held by the frame and their seating on the fulcrum member.

[0034] The device provides for symmetrical loading of the capsule, which is crucial to its proper working, and to avoid premature shattering due to vibration, impact or other mechanical shock. Prior art devices are generally non-symmetrical and risk off-centre loading of the capsule.

[0035] The construction of the device reduces shielding of the bulb from hot gases by parts such as the frame arms. Since these can be made less robust, due to the reduced load they have to sustain, their thickness can be reduced, reducing their shielding effect.

[0036] Reducing the reaction load on the arms also enables relaxation effects to be accommodated safely. Relaxation causes seals to begin leaking after tightening, and it is usual to try to compensate by initial over tightening if the arm load is reduced, relaxation is reduced together with the need for over tightening.

[0037] Another advantageous effect of reducing the mass of the sprinkler outlet assembly particularly the arms, which are closest to the capsule as a by-product of reducing stresses sustained by the side arms is to bring about reduction of the thermal conductivity factor affecting the response time of the outlet. The structure acts as a heat sink which draws heat away from the capsule as it is heated by fire gases. Consequently, reduction in the metal mass reduces the heat sink effect, and improves the response time significantly.

Claims

1. A sprinkler outlet closure device comprising a nozzle closure member, a fallible member designed to fail above a threshold temperature being positioned to retain the closure member in a nozzle closing position, and lever means bearing on said abutment means of the capsule, characterised in that said lever means (25, 26) has fulcrum means (18) arranged to bear in said nozzle closure member (17) and serving to divide load acting through fallible member (30) in proportion to the mechanical advantage of said lever means (25, 26).

2. A device according to claim 1 characterised in that the nozzle closure member (17) includes a belleville spring (15) the rim of which is pressed against a bearing surface (12) provided in the nozzle, and a substantially bowl shaped member, having means for locating in the central aperture of the belleville spring and abutting the rim of said aperture, and a rim (18) directed away from the belleville spring which is adapted to serve as said fulcrum means.

3. A device according to claim 2, characterised in that at least two diametrically opposed levers (25, 26) are balanced on said rim (18) and extend to the centre of the member, the other ends of the levers extending outwardly to engage with side frame members (19, 20).

4. A device according to claim 3 characterised in that the inner ends of the levers are shaped to define and aperture between said inner ends into which is inserted an end portion (29) of a hollow glass capsule (30) of generally cylindrical shape which constitutes said fallible member, the capsule having a reduced diameter end portion (29) which defines shoulders on the main part of the capsule which abut the ends of the levers, thereby providing said abutment means.

5. A device according to claim 4 characterised in that said capsule (30) has an other end which is located against an adjustment screw (23) in an aperture in a frame part 21, the screw being displaceable to adjust the force exerted through the capsule onto the closure member (17).

6. A device according to claim 3, characterised in that said levers (125, 126) are cranked to allow use of a miniature capsule (130).

7. A device according to claim 5 characterised in that said screw is contained in a boss (223) which extends inwardly towards said closure, to accommodate a reduced length capsule (230).

8. A device according to claim 5, characterised in that said levers (225, 226) engage in slots in stub members (214, 215) instead of in side frame members.

9. A device according to claim 1 characterised in that the fallible member comprises a link or other member (313) of a fusible material.

10. A device according to claim 9, characterised in that said link (313) is comprised of two or more pieces of rigid metallic material which are connected end to end or face to face by solder.

11. A device according to claim 9, characterised in that said link (313) is composed of a fusible material such as a synthetic plastics material which softens when the ambient temperature rises beyond a threshold temperature.

Drawing