(54) IMPROVEMENTS IN OR RELATING TO FIREEXTINGUISHANT SPRINKLERS(71) We, ANGUS FIRE ARMOURLIMITED, a British Company of DunlopHouse, Ryder Street, St James's, London SWI, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an improvement in or modification of the invention described in the specification of our copending UK Application No. 14,033/77 (SerialNo. 1,582,360).
In said specification there is described a sprinkler comprising a support body, a fluid passage extending through the support body, a closure member having a sealing surface which extends in the direction of flow of fluid through the fluid passage to effect a fluid-tight seal in the fluid passage and a temperature sensitive element acting between the support body and the closure member, the closure member being able to move in both an axially inwards and an axially outwards direction relative to the fluid passage to accommodate relative movement between the temperature sensitive element and the fluid passage under normal operating conditions and the sealing surface being constructed and arranged to maintain said fluid-tight seal during such movement of the closure member.
In accordance with the present invention a sprinkler comprises a temperature sensitive element, a support body supporting the temperature sensitive element, the support body being provided with a fluid flow passage for the flow of extinguish ant fluid through the sprinkler, an O-ring seal extending around an interior periphery of the fluid flow passage and the temperature sensitive element having a sealing surface which extends in the direction of flow of fluid through the passage and bears against the O-ring seal in sealing contact therewith to prevent the flow of extinguishant fluid through the fluid passage under normal operating conditions.
The sealing surface of the temperature sensitive element may extend parallel with the axial direction of fluid flow through the passage, or at a slight angle thereto (e.g. in the range 0" to 150) for reasons described in our above mentioned co-pending patent application. Higher angles may however be used, the requirement being that.the sealing surface extends in the said direction of fluid flow and not at right angles thereto.
The present invention is particularly applicable to temperature sensitive elements such as glass bulbs but may be employed also where the temperature sensitive element comprises a fusible linkage or other means responsive to temperature changes.
One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 is a part-sectional view of a fire extinguishant sprinkler in accordance with the present invention, andFigure 2 shows in detail the temperature sensitive glass bulb illustrated in Figure 1.
A fire extinguishant sprinkler comprises a brass support body 10 having an externally screw-threaded base portion 11 for attachment to the pipework of an extinguishant system. A smooth bore cylindrical passage 12 for the flow of extinguish ant fluid extends centrally through the base portion. Two support arms12a extend from the base portion 11 in a direction generally axial and parallel with the direction of fluid flow through the base portion. The ends 13 of the arms furthest from the base portion are inclined inwards to a boss 14 into which a spray shroud (not shown) may be fitted.
The boss 14 is shaped to provide a seating surface for one end of a temperature sensitive glass bulb 15, the glass bulb being of a conventional kind insofar as it contains a suitable liquid, such as paraffin, but of an unconventional shape as illustrated inFigure 2 and described in more detail below. When subjected to temperatures greater than a predetermined level the expansion of the paraffin shatters the bulb.
The other end of the bulb is formed with a shoulder 16 and a frusto-conical shape neck portion which provides a sealing surface 17 to bear against an O-ring seal 18 positioned between the said sealing surface 17 and cylindrical fluid passage 12.
The glass bulb 15 is of circular crosssectional shape and formed of glass having a thickness of 1 mm. The bulb has a maximum diameter at a central substantially cylindrically shaped portion 19 (see Figure 2), and the diameter of this portion is less than the diameter of the fluid passage 12 in the sprinkler body, so that the glass bulb may be assembled in relation to the body by insertion through said passage 12. The sealing surface 17 of frusto-conical shape has an included angle of 20 in cross-section as shown in Figure 2.
In the assembly of the support body 10, glass bulb 15 and O-ring 18, the O-ring is held in position against migration in a direction away from the boss 14 by means of a thin tubular metal sleeve 20 which fits within the fluid passage 12. The sleeve is formed with a radially outwardly extending lip 21 at the end furthest from the boss 14 for location between the screw-threaded portion 11 and associated pipework (not shown) thereby to prevent movement of the sleeve within the passage.
In use of the sprinkler under normal operating conditions the glass bulb and 0ring seal co-operate to prevent escape of pressurised fluid from within the passage 12 and associated pipework. Since the sealing surface 17 provided on the glass bulb has only a small angle of taper any axial movement of the glass bulb relative to theO-ring seal as a result of temperature and pressure changes causes insufficient change in the contact pressure between the sealing surface 17 and O-ring 18 to affect the quality of the sealing performance adversely.The primary purpose of the taper of the sealing surface is to facilitate ease of displacement of the fractured glass bulb from the seal under the action of extinguishant fluid pressure in the event of a fire, through the direction of said taper also serves to discourage migration of the glass bulb back into the passage such as might occur as a result of successive cyclical temperature variations if the associated pipework system were unpressurised and the glass bulb not continuously urged to bear against the boss 14. The taper also avoids the need for close tolerance dimensions of the sealing surface.
It will be appreciated, however, that in an alternative embodiment of the present invention the sealing surface 17 may extend parallel with the axial direction of flow of fluid through the flow passage 12, that is, the sealing surface may be cylindrical.
In a sprinkler in accordance with thepresent invention there is eliminated theneed to provide a closure member such asdescribed in our co-pending U.K. PatentApplication No. 14,003/77 (Serial No.
1,582,360). Accordingly there results areduction in cost of the components anddecrease in time taken to assemble thecomponents.
WHAT WE CLAIM IS:1. A sprinkler comprising a temperaturesensitive element, a support bodysupporting the temperature sensitiveelement, the support body being provided with a fluid flow passage for the flow ofextinguishant fluid through the sprinkler, anO-ring seal extending around an interior.
periphery of the fluid flow passage and the temperature sensitive element having asealing surface which extends in thedirection of flow of fluid through thepassage and bears against the O-ring seal insealing contact therewith to prevent the flow of extinguishant fluid through the fluidpassage under normal operating conditions.
2. A sprinkler according to claim 1wherein the sealing surface extends substantially parallel relative to said directionof fluid flow.
3. A sprinkler according to claim 1 or claim 2 wherein the sealing surface extends -at an angle between 0 and 15 relative tosaid direction of fluid flow.
4. A sprinkler according to claim 3 wherein the sealing surface tapers inwards in a direction opposite to the normal direction of fluid flow through the fluid passage.
5. A sprinkler according to any one of the preceding claims wherein the temperature sensitive element comprises a glass bulb.
6. A sprinkler according to claim 5 wherein the glass bulb and fluid passage are of substantially circular cross--sectional shape and the glass bulb has a maximum diameter less than the diameter of the fluid passage.
7. A sprinkler according to claim 5 or claim 6 wherein the glass bulb is formed with a neck portion which constitutes the sealing surface.
8. A sprinkler according to claim 7wherein the glass bulb is provided with asubstantially cylindrical shape body portionseparated from the neck portion by ashoulder.
9. A sprinkler constructed and arrangedsubstantially as hereinbefore described withreference to the accompanying drawing.
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