GB2213718A - Fire extinguishing sprinkler head - Google Patents

Abstract

A fire extinguishing sprinkler head 1 comprising a body member 2 having a water discharge orifice, a valve member 22 normally closing the orifice, at least one frame arm 9 extending from the body member 2 to provide, remote from the discharge orifice, a support and abutment location 12 for the ends of a pair of heat sensitive elements 20 spaced-apart from one another by a distance equal to, or slightly exceeding, the thickness 11 of the frame arm(s) 9, with the other end of each element 20 bearing, at spaced-apart locations, on the valve member 22 to urge the latter into its closing position, whereby at least one of the elements 20 is always fully exposed to any radiation source over a 360 DEG area around the head 1, irrespective of the orientation of the sprinkler head 1. <IMAGE>

Description

FIRE EXTINGUISHING SPRINKLER HEAD This invention relates to a fire extinguishing sprinkler head. A well-known construction of sprinkler head comprises a water discharge orifice normally closed by a heat sensitive element e.g. a liquid filled glass bulb or a fusible strut or link, with the element fracturing upon an elevated threshold temperature being sensed, to open the orifice and permit a column of water to strike a spray generating deflector plate mounted on the head.

A traditional design of head comprises a body member, e.g. of brass, to one side of which extends a threaded mounting spigot from the other side of which extend a pair of spaced-apart, bowed frame arms located diametrically opposite one another with regard to the spigot axis and adapted to support a loading member engaging one end of the heat sensitive element, such as a bulb referred to above, and to apply compressive loading on the bulb sufficient to counteract the water pressure on a valve member which is engaged by the other end of the bulb and pressed into water sealing engagement with the discharge orifice.A problem with this type of sprinkler head is that whilst in one orientation the element is fully exposed to e.g. infra-red radiation and hence fully operational, in an orientation rotated 900 from the fully exposed orientation, the frame arms obscure and hence shield the heat sensitive element from opposite sides of the radiation source, and thus the head has two blind spots 1800 apart which could delay or even prevent activation of the sprinkler head.

One proposal for mitigating the problem of frame arm shadow so as to ensure exposure of a major portion of the element at any orientation of the head shielding is described in our co-pending GB Patent Application 878525.

Apart from the shielding problem, there is an increasing requirement for faster response times from sprinkler devices than are possible with conventionally dimensioned glass bulbs, and to achieve faster response the physical size and consequently the volume of liquid contained within a bulb is reduced, to produce a slimmer bulb, necessarily having a reduced heat collecting surface area.

According to the present invention there is provided a fire extinguishing sprinkler head comprising a body member having a water discharge orifice, a valve member normally closing the orifice, at least one frame arm extending from the body member to provide, remote from the discharge orifice, a support and abutment location for the ends of a pair of heat sensitive elements spaced-apart from one another by a distance equal to, or slightly exceeding, the thickness the frame arm(s), with the other end of each element bearing, at spacedapart locations, on the valve member to urge the latter into its closing position, whereby at least one of the elements is always fully exposed to any radiation source over a 3600 area around the head, irrespective of the orientation of the sprinkler head.

The sprinkler head in accordance with the invention, by employing two spaced-apart heat sensitive elements in the disposition defined above results in a construction in which the problem of the heat sensitive element possibly being totally or partially screened from a radiation source by being in the "shadow" of a frame arm is eliminated.

In one embodiment, two frame arms may be provided, the arms bing spaced apart and located in a common, diametral plane. In this case, the heat sensitive elements would be located in a second diametral plane extending orthogonally, or generally so, with respect to the first diametral plane.

The valve member may take the form of a valve disc, with a deformable "O"-ring interposed between a portion of the valve disc and a valve seat, which is preferably chamfered, of the body member, the arrangement being such that as the ends of the heat sensitive element adjacent the discharge orifice are located on diametrically opposite portions of the valve disc, fracture of either element results in the loading on the valve disc into its seating position becoming unbalanced, and the valve disc being displaced from its seating location by the water pressure. The valve disc is conveniently provided with a pair of diametrically spaced-apart blind location recesses, each to receive one end of one heat sensitive element, while the sealing ring is conveniently snapped into a circumferential retaining groove in the disc.

Remote from the discharge orifice, the two ends of the heat sensitive elements may be compressibly loaded by two spaced-apart and individually adjustable screws in tapped holes in a common bridge bar. The bridge bar at its side remote from the heat sensitive elements may be provided with a "V"-shaped recess to receive a locating wedge carried by the frame arm ends. Beyond the bridge bar, the sprinkler device is, in the traditional manner, provided with a suitable deflector, adapted to be struck by the water column issuing from the opened water orifice, upon the sprinkler head being activated by fracture of one or other of the heat sensitive elements.

An integral, threaded mounting spigot may extend from the opposite side of the head to that from which the frame arm(s) extend.

The sprinkler head may have its frame arm(s) formed integrally with the body member, or alternatively may be of two-part construction with the frame arm(s) formed with an attachment flange and with the body member having a seating flange, with the two parts connected with the flanges butted together, by the use of two connection screws.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a part sectional side elevation of a sprinkler head in accordance with the invention, and Figure 2 is an end elevation of Figure 1, in the direction of arrow A.

In the drawings is illustrated a fire extinguishing sprinkler head 1 comprising a body member 2 having an externally threaded mounting spigot 3 extending from a flange 4 of larger diameter than the spigot by which spigot the head 1 may be screwed into a water supply adaptor fitted for example to a ceiling. The body member 2 has a through bore comprising a frusto-conical water inlet throat 5 converging to a contiguous delivery bore 6 terminating at a discharge orifice 7.From an opposite side of the flange 4 to the spigot 3 extends a frame 8 comprising a a pair of arms 9 extending away from the flange 4 and located in a common radial plane 18, having a thickness 11, in a plane orthogonal to the plane 1PI. Remote from the flange 4, the arms 9 converge to meet at a boss 12 having a wedge 13 and a tapped hole 14 into which is screwed a retainer 15 for a deflector 16. A bridge bar 17 has a "v"-shaped recess to receive the wedge 13 and has a pair of spaced-apart tapped holes 18 in each of which is an adjustable screw 19.Each screw 19 bears, with slight pressure, on one end of similarly spacedapart frangible, elongate, heat sensitive elements or bulbs 2, the spacing being such that, as best seen in Figure 2, the heat sensitive elements 2 exceed the thickness 11 of the arms 9 and are located in a common radial plane 21 extending orthogonally to the plane 11. At their other ends, the heat sensitive elements 2 bear on one side of a valve disc or saddle 22 engaging blind location recesses 23 provided in the disc 22. The latter is adapted to close the discharge orifice 7 by means of a sealing ring 24 snapped into a circumferential retaining groove in the disc 22 and sealing against a chamfered valve seat 25, under loading transmitted from the screws 19 against the water pressure within the bore 6, and metal to metal contact between an annular flange 26 of the disc 22 and a radial seat 27 beyond the chamfered seat 25.

As is apparent by cons-idering Figures 1 and 2, one or other of the heat sensitive elements 2 will always be exposed to any radiation source over a 3600 area around the sprinkler 1 and, in contrast to prior art proposals, is never in the shadow of an arm 9, which shadow restricts the sensitivity of the sprinkler head 1 and might delay, or prevent, its activation by fracture of one or both heat sensitive elements 2 and the consequent unbalancing of the loading on the disc 22 whereupon the water pressure within the bore 6 forces the disc 22 and the heat sensitive element 2 away, so that water may impinge upon the deflector 16 to generate the desired spray pattern.

Claims (13)

1. A fire extinguishing sprinkler head comprising a body member having a water discharge orifice, a valve member normally closing the orifice, at least one frame arm extending from the body member to provide, remote from the discharge orifice, a support and abutment location for the ends of a pair of heat sensitive elements spaced-apart from one another by a distance equal to, or slightly exceeding, the thickness the frame arm(s), with the other end of each element bearing, at spaced-apart locations, on the valve member to urge the latter into its closing position, whereby at least one of the elements is always fully exposed to any radiation source over a 3600 area around the head, irrespective of the orientation of the sprinkler head.

2. A sprinkler head as claimed in Claim 1, wherein two frame arms are provided, the arms being spaced apart and located in a common, diametral plane.

3. A sprinkler head as claimed in Claim 2, wherein the heat sensitive element are located in a second diametral plane extening orthogonally, or generally so, with respect to the first diametral plane.

4. A sprinkler head as claimed in any preceding Claim, wherein the valve member takes the form of a valve disc, with a deformable "O"-ring interposed between a portion of the valve disc and a valve seat of the body member, the arrangement being such that as the ends of the heat sensitive element adjacent the discharge orifice are located on diametrically opposite portions of the valve disc, fracture of either element results in the loading on the valve disc into its seating position becoming unbalanced, and the valve disc being displaced from its seating location by the water pressure.

5. A sprinkler head as claimed in any preceding Claim, wherein remote from the discharge orifice, the two ends of the heat sensitive elements are compressibly loaded by a common bridge bar.

6. A sprinkler head as claimed in any preceding Claim, wherein the valve disc is provided with a pair of diametrically spaced-apart blind location recesses, each to receive one end of one heat sensitive element.

7. A sprinkler head as claimed in any preceding Claim, wherein the sealing ring is snapped into a circumferential retaining groove in the disc.

8. A sprinkler head as claimed in Claim 5 or Claim 6, wherein a side of the bridge bar remote from the head sensitive elements is provided with a "V"-shaped recess to receive a locating wedge carried by the frame arm ends.

9. A sprinkler head as claimed in any one of Claims 5 to 8, wherein beyond the bridge bar, the sprinkler device is, in the traditional manner, provided with a suitable deflector, adapted to be struck by the water column issuing from the opened water orifice, upon the sprinkler head being activated by fracture of one or other of the heat sensitive elements.

18. A sprinkler head as claimed in any preceding Claim, wherein an integral threaded mounting spigot extends from the opposite side of the head to that from which the frame arm(s) extend.

11. A sprinkler head as claimed in any preceding Claim, wherein the frame arm(s) of the sprinkler head is/are formed integrally with the body member.

12. A sprinkler head as claimed in any one of Claims 1 to 8, of two-part construction, with the frame arm(s) formed with an attachment flange and with the body member having a seating flange, with the two parts connected with the flanges butted together, by the use of two connection screws.

13. A fire extinguishing sprinkler head substantially as hereinbefore described with reference to the accompanying drawing.