GB2076652A - Fire extinguisher discharge head - Google Patents

Abstract

Discharge head for fire extinguishing apparatus e.g. using pressurised overhead or other containers or a water sprinkler system, includes a discharge opening closed by a plug or other closure which is retained by an arrangement of one or more temperature responsive elements such as frangible bulbs and one or more resiliently deformable elements such as a series of disc springs arranged in a stark, so permitting discharge automatically in response both to a rise in temperature of the head above a predetermined level or on a rise in pressure acting on the closure e.g. due to excessive heating of the pressure container itself due to an outbreak of fire not yet sensed by the head. <IMAGE>

Description

SPECIFICATION Fire extinguisher discharge head This invention relates to discharge heads for fire extinguishing apparatus of the kind including temperature responsive retaining means which deforms to permit discharge upon attaining a predetermined temperature.

The apparatus may be a sprinkler system having a plurality of discharge heads, the extinguishant used being commonly water; or it may be of a type having a pressure container holding a charge of fluid or powder extinguishant and/or a propellant, for example an automatically operating extinguisher using "BCF" or other halogen compounds as propellant and/or extinguishant ("Halon" systems).

The invention may be applied to discharge heads incorporating more than one temperature sensitive element (e.g. fluid filled bulbs) as described and claimed in our British Patent 1349935 and/or may incorporate remotely controlled or actuated overriding means for effecting discharge independently of rise in ambient temperature in the immediate area of the discharge head as described and claimed in our British Patent 1363945.

The object of the invention is to provide a discharge head for pressure operated fire extinguishing apparatus which is particularly safe and reliable in use yet which is of simple construction, easily calibrated to close tolerances, and readily assembled and maintained.

According to the invention there is provided a discharge head for fire extinguishing apparatus including structure defining a discharge opening for a flow of extinguisher fluid and/or fluid propelled extinguishant, a closure urged to a position closing said opening by an arrangement of elements acting between the closure and a locating formation of said structure, said elements including at least one temperature responsive retaining means adapted to deform in response to a rise in ambient temperature above a predetermined level for release of the closure from said position and at least one resilient member adapted to deform in response to a rise in pressure acting on said closure above a predetermined level to permit displacement of the latter from the closed position; whereby discharge will occur on a rise in said temperature or said pressure above the respective predetermined levels.

Preferably said elements are arranged as a stack abutting the closure at one end and a locating abutment of said structure at the other end and including a plurality of resilient members in the form of a series of disc springs, selection of the number of springs used and their disposition in the stack providing particularly convenient and consistent selective adjustment of the required pressure loading in compact dimensions.

One embodiment of the invention is now more particularly described with reference to the accompanying drawings wherein: Figure 1 is a vertical section of a fire extinguisher discharge head, and Figure 2 is an inverted plan view thereof.

Though described in connection with a suspended or overhead pressure container extinguisher said head might have applications to piped water sprinkler systems.

The head comprises a cage-like body structure 10 which may be formed of plastics or other non metallic material having a low coefficient of thermal conductivity to give speedy response and reduce the "heat-sink" effect, as described and claimed in our British Patent 1 382643.

The upper (as viewed in the drawing) part of structure 10 includes a neck formation 11 which is externally threaded to be screwed into the mouth of a pressure container (or duct) (not shown) of the apparatus and defining a central through opening 12 which communicates directly with the container or duct interior when assembled. A pressure gauge 8 and a connector 9 which may include a resiliently loaded self closing plunger valve as used on pneumatic tyres are mounted on formation 11 to communicate with opening 1 2 for checking and recharging purposes.

An abutment formation 1 3 of structure 10 is spaced axially remote from opening 1 2 by a pair of limbs 14 spaced clear of the central axis of the head, one of which may be provided with a bore or other mounting for a remotely controlled explosive or other overriding device 1 5 as described in our said British Patent 1 363945.

Located in opening 12 is a plug-like closure member 1 6 having a flange at its outer end which abuts an outer end face of formation 11 to define a fully closed position. At this position an O-ring seal 1 7 is in engagement with the cylindrical wall of opening 12 to form a fluid and pressure tight seal.

Closure 1 6 is retained at the closed position by a stack of elements comprising a pair of frangible fluid filled temperature responsive bulbs 1 8 of conventional design located in end to end relationship by a central flanged disc 19. The lower end of the pair of bulbs locates in a socket defined in a plunger 20 which is a sliding fit in an axial bore in formation 13. The lower end of plunger 20 is stepped and is abutted by a stack of disc springs 21 in the shape of dished washers with are retained by a cap 22 screwed onto a threaded bottom spigot of formation 1 3. A tail portion of plug 20 extends into a clearance hole 23 at the centre of cap 22.

The stacked springs 21 urge closure 1 6 to the closed position and the loading applied thereto can be selectively varied by choice of the type and number of disc springs used and their disposition, for example three single springs can be employed arranged so tht they are alternately dished in opposition directions as shown in the drawing or two or more springs may be arranged so that they are dished in the same direction to nest within one another.

If pressure within the extinguisher container should rise above a predetermined level, for example due to an outbreak of fire heating the end of the container remote from the discharge head, closure 1 6 will be displaced downwards under said pressure, compressing the stack of springs 21 until seal 17 enters a splayed portion of opening 12 leading to the mouth so permitting discharge past the closure.

Additionally the head will, of course, respond in the normal way to rise in ambient temperature past the predetermined level causing fracture and collapse of one or both bulbs 1 8 to release closure 1 6 from opening 12 and/or operation of the overriding device 1 5 (if fitted) to fracture the lower bulb 1 8 by an electrical signal from a remote station, for example a heat or smoke detector and/or manual control.

Claims (11)

1. A discharge head for fire extinguishing apparatus including structure defining a discharge opening for a flow of extinguisher fluid and/or fluid propelled extinguishant, a closure urged to a position closing said opening by an arrangement of elements acting between the closure and a locating formation of said structure, said elements including at least one temperature responsive retaining means adapted to deform in response to a rise in ambient temperature above a predetermined level for release of the closure from said position and at least one resilient member adapted to deform in response to a rise in pressure acting on said closure above a predetermined level to permit displacement of the latter from the closed position: whereby discharge will occur on a rise in said temperature or said pressure above the respective predetermined levels.

2. A head as in Claim 1 wherein said elements are arranged as a stack abutting the closure at one end and a locating abutment of the structure.at the other end.

3. A head as in Claim 1 or 2 including a plurality of resilient members in the form of a series of,disc springs.

4. A head as in Claim 1, 2, or 3 wherein said temperature responsive retaining means is a fluid filled frangible bulb.

5. A head as in Claim 4 including a pair of said bulbs dispersed in end to end relationship.

6. A head as in any one preceding claim wherein the closure is a plug like closure member received in the discharge opening and retained therein by said arrangement of members.

7. A head as in Claim 6 including a sealing element acting between the closure member and wall structure defining said opening to provide a fluid and pressure tight seal with said member at a fully closed position.

8. A head as in Claim 7 wherein a portion of said opening leading to its mouth is splayed whereby discharge will be permitted on axial displacement of the closure member from the fully closed position sufficient for the sealing member to enter said splayed portion.

9. A head as in any preceding claim including an overriding device operable to release the closure independently of temperature or pressure induced deformation of any of said elements.

1 0. A discharge head for fire extinguishing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

11. A sprinkler system, pressure container extinguisher, or other fire extinguishing apparatus including a discharge head as in any preceding claim.