GB2122891A - Fire extinguishers - Google Patents

Abstract

A fire extinguisher device comprises a container of pressurised extinguishant having a venting port fitted with a burstable diaphragm (49) which is supported externally by means of a backing plate (53). On on removal of the backing plate by an appropriate actuator the pressure of extinguishant can burst the diaphragm to allow discharge of the extinguishant through the venting port. In order to reduce the forces required to actuate the mechanism required for removal of the backing plate, the backing plate is supported by an abutment (54) making rolling contact with a counter surface, such that the release of the backing plate (53) can be effected by rolling, rather than sliding, friction. To enable prolonged resistance of the extinguisher mechanism to harsh conditions, the backing plate and associated actuator mechanism are enclosed within a chamber sealed by means of a secondary burstable diaphragm. The burstable diaphragm may be provided with lines of weakness to promote bursting thereof without discharge of segments from the venting port. <IMAGE>

Description

SPECIFICATION Fire extinguishers The invention relates to fire extinguishers and, more specifically, to discharge units for containers of pressurised fire extinguishant.

In fire suppression systems requiring high mass-flow rates of extinguishant, it is known to achieve rapid discharge of extinguishant from a container by opening a relatively large bursting diaphragm fitted to a venting port of the container.

The contents are thus permitted to be ejected, either by the vapour pressure of the extinguishant, or by pressure derived from other means, for example an additional gas filling. Containers of this kind have been proposed for use in, for example, fire-suppression systems in military vehicles.

It is also known to support such diaphragms by a backing plate which, on removal by an electric or explosive actuator or manually, allow the container pressure to burst the diaphragm.

However, such arrangements have a number of disadvantages. The frictional forces upon the actuating mechanism may be unacceptably high, particularly when the backing plate is to be displaced by a very low energy electro-solenoid or electrically initiated protractor or retractor in a very small fraction of a second or a manual means where a small movement of low force is required.

The diaphragms tend to disintegrate into pieces which are projected at dangerously high speeds and possibly into dangerous or awkwardly-sited places. It is also hazardous to transport the known devices when in the charged and primed condition, for which reason the venting port is customarily fitted with an anti-recoil plug until the extinguisher is installed. This plug must, however, be removed before installation of pipes or dispensers to cooperate with the venting port, and at this stage the known extinguishers are in a dangerous condition.

It it accordingly one object of the invention to provide a fire extinguisher device of the kind referred to, wherein the forces required for mechanical actuation thereof are reduced.

It is a further object of the invention to provide a fire extinguisher device which is usable in harsh conditions for prolonged periods of time.

It is a yet further object of the invention to provide a fire extinguisher device having improved safety characteristics.

In accordance with one aspect of the invention there is provided a fire extinguisher device comprising a container of pressurised fire extinguishant; a burstable diaphragm closing an orifice of said container; an external backing member supporting said diaphragm against bursting thereof by the pressure of said extinguishant, and a mechanism for retaining said backing member in contact with said diaphragm, said mechanism being actuatable to release said backing member and allow bursting of the diaphragm whereby extinguishant from said container becomes discharged through a venting port, wherein said mechanism includes an abutment member making rolling contact with a counter surface against which pressure is exerted thereby to transmit support to said backing member, and means for transmitting rolling motion to said member to release it from said counter surface.

Preferably, the backing member is mounted in a casing which provides a flow path for the discharging extinguishant and is releasable by operating mechanism including actuating members which are isolated from said flow path and from the high pressures generated by the discharging extinguishant. Suitably, the backing member is held and released by a rotary shaft at least one end of which extends through a wall of said casing to be actuated by, for example, an explosive protractor or a cable system.

Advantageously, the said abutment member comprises a roller, and the said means for transmitting rolling motion to said abutment member comprises a rotary shaft carrying a cage within which the two ends of said roller are supported. In one such arrangement, the said cage comprises a pair of elongate slots allowing relative movement between the axis of the roller and the cage and the said rotary shaft further carries a supporting surface-arranged to engage and hold said roller against said counter surface, whereby, whilst constrained by said cage, the roller can roll between said supporting surface and said counter surface during actuation of the said mechanism.

According to another aspect of the invention, there is provided in the flow path of extinguishant from said burstable diaphragm to said venting port, a second burstable diaphragm providing a secondary seal enclosing said backing member and any associated components of said actuating mechanism.

According to yet another aspect of the invention, the said burstable diaphragm is clamped at its periphery and is formed with lines of weakness which extend outwardly from the centre of the diaphragm and which promote bursting of the diaphragm into segments which are held at their roots against detachment from the clamped periphery of the burst diaphragm. A similar arrangement may be utilised for the second diaphragm.

Further features and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings and the appended Claims.

Figure 1 is a sectional elevation, on line I-I of Figure 2, showing one form of discharge unit according to the invention; Figure 2 is a sectional plan, on the line Il-I I of Figure 1; Figure 3 is a part sectional view in the direction of arrow Ill of Figure 2; Figure 4 is a sectional elevation showing another form of discharge unit according to the invention; Figure 5 is a section on the line V-V of Figure 4; Figure 6 is a detail section on the line VI--VI of Figure 5, showing a displaceable abutment; Figure 7 is a fragmentary sectional elevation showing a further form of discharge unit according to the invention; Figures 8 and 9 are detail sections showing alternative forms of burstable diaphragms;; Figure 10 is a view similar to that of Figure 1 of yet another embodiment of the invention; Figure 11 is a sectional elevation on the line Xl-Xl of Figure 10, Figure 12 is a part sectional elevation taken on the line Xll-Xll of Figure 10; Figure 13 is a sectional elevation taken on the line Xlll-Xlll of Figure 10, and Figure 14 is a sectional elevation of the device shown in Figures 10 to 13, taken from the opposite side of the device from that shown in Figure 10.

Referring to Figures 1 to 4 of the drawings, the discharge unit 10 is securely screwed into the mouth of a container 11 of pressurised fire extinguishant, such as HALON 1301, to close the mouth completely.

The unit 10 comprises a casing 12 to which is bolted a port member 13 and a cover 14. A frangible metal diaphragm 1 5 of dished shape is clamped around its circular periphery into the member 13 by means of a screwed clamping ring 16, to close the conduit opening, and is supported by a backing plate 17. The backing plate is pivotally mounted on a shaft 1 8 and held at its opposite side by a lever 1 9 the short arm of which abuts against a hardened insert 20 in the plate 1 7. The lever is pivotally mounted on a pin 21, and has at the end of its longer arm a recess 1 9A which engages with a roller 27 which is supported in elongated slots 28 of spaced brackets 22A carried by a shaft 22. The shaft 22 carries operating lugs 23 and 24, externally of the casing 12.The lever 1 9 is urged to its holding position (shown in full lines) by a spring 25, and a buffer 26 is provided to be engaged as the lower arm reaches its release position (shown in broken lines).

It will be noted that the lever 1 9 is locked in its holding position by the recess 1 9A engaging roller 27 which is held in place by the shaft 22, but will be freed when the shaft 22 is rotated (clockwise as viewed) so that the roller 22 can roll between the surface of recess 1 9A on the one hand and the edges of slots 28 on the other until it escapes from the lever 19. A semi-circular cut-away 22B in the shaft 22 allows pivoting of the lever 1 9 into the position shown in broken lines in Figure 1. The shaft 22 is lightly spring-loaded (anti-clockwise) to its holding position, to prevent unintended release of the lever 1 9 when there is no pressure on the diaphragm 15.

The shaft can be rotated by turning either of the lugs 23 and 24. As shown in Figure 3, the lug 23 is actuated by a push-rod 29 which is operated in a conventional manner by a lever arrangement indicated at 30, or by a cable system (not shown).

The lug 24 is operated by an explosive protractor 31 in which a small rod 32 is driven by an electrically-operable explosive charge in a close cylinder 33. The mechanical advantage provided by the lever 1 9 minimises the force required to operate the shaft 22, and the presence of roller 27 avoids the need for sliding friction between the shaft 22 and lever 19.

Thus, on rotating the shaft 22 by either manual or electrical operation, the lever 1 9 pivots to release the plate 1 7. On release, the extinguishant pressure immediately ruptures the diaphragm 1 5 and swings open the plate 1 7 which engages a buffer 34 at the end of its rapid movement. The extinguishant then discharges at high speed through the port member 1 3 and out through discharge port 35.

As shown in Figure 2, the diaphragm 1 5 is formed with lines of weakness 36, e.g. scores, radiating outwardly from the centre of the disc-like diaphragm. On rupturing, the diaphragm ruptures into segments which are held at their roots 37 against detachment from the clamped periphery.

As indicated in Figure 2, an optional second burstable metal diaphragm 38, similarly formed with lines of weakness, is clamped over the port 35, to be ruptured, almost simultaneously with diaphragm 1 5, on dishcarge of the extinguishant.

The diaphragm 38 is clamped in position by a screw ring 39, and protects the interior of the casing against the environment, particularly corrosive moisture. A protective plug 40 may close the port when the extinguisher is not in use.

Returning to Figure 1 , the backing plate 1 7 is formed (optionally) with a central relief bore 41 which is formed with radiussed edges to avoid cutting the diaphragm, and with a restricted outlet 42. Thus, if the extinguishant pressure rises above a predetermined maximum safety value, the diaphragm will rupture at its centre to allow discharge of the extinguishant, at high velocity but low rate. In such a discharge, the extinguishant would flow to port 35, and either burst the diaphragm 38 and escape to atmosphere through bleed channels in the plug 40 or excape through a relief valve in the casing.

A further advantage of the discharge unit described above is that the chamber 43 which houses that part of the operating mechanism which requires external contact, is isolated from the flow path of the discharging extinguishant, as is the explosive protector which should be replaced and/or checked periodically. This arrangement should remove the danger of the cover 14 being dislodged by discharge pressure if, for example, the backing member 17 were released inadvertently while the plug 40 was in position.

The diaphragm 1 5 should be hermetically sealed around its periphery 44, possibly with the assistance of a ring 45 which acts to prevent rubbing or galling on the surfaces of the periphery of the diaphragm during tightening of the locking ring 1 6 into the port member 13. Any extinguishant leakage which might occur should, however, discharge to atmosphere.

A passageway 46 extends from the chamber 43 and, at its end, receives an electrical plug 47 which carries electrical connectors for cables (not shown) which extend through the passageway to the protractor contacts.

A pressure relief valve may be provided, as at 48 in Figure 1, to release pressure caused by possible leakage past the diaphragm 1 5 into the casing 1 2. Valve 48 would be arranged to open at, say,2 atmosphere above ambient pressure, and certainly below the bursting pressure for the diaphragm 38.

Particularly when several extinguishers are used to feed into a common distributing pipe, to a location such as an engine compartment, it is desirable to produce a one-way valve (not shown) at the discharge port 35. Such a valve, which may comprise a hinged metal flap, or rubber-like flaps supported by a grill, may replace the diaphragm 38 in partially serving the same purpose as that environmental diaphragm.

It is intended that the discharge unit be suitable for extended use in harsh conditions such as marine application and military field use. Thus, the components should be made from materials, usually metallic, which are inherently resistant to or have been suitably treated against corrosion, and cover 1 4 should be applied with a suitable sealing compound; this sealing, together with the environmental seal provided by the diaphragm 38 acts to protect the operating mechanism against corrosion.

In the alternative form of discharge unit shown in Figures 4 to 6, a diaphragm 49 is clamped by means of a ring 50 into member 51 which provides a spigot connection for a pressurised extinguishant container (such as 11 in Figure 1) and is bolted onto casing 52. The diaphragm is supported by a hinged L-shaped backing plate 53 which is held in its support position by an abutment roller 54. The roller is retained by its reduced end lengths 55 in cases 56 extending from an operating shaft 57, and central length 58 of the roller is sandwiched between the shaft 57 and a hardened insert 59 at the lower end of the normally-vertical limb 60 of the backing plate.

The shaft 57 is rotatable, either manually through a cable system indicated at 61, or by an explosive protractor 62 acting on a shaft lug 63 in a manner similar to that of protractor 31 described above. On rotation of the shaft (in a clockwise direction as viewed in Figure 4), the cages 56 displace the roller 54 to free the backing plate 53 which then snaps open under the action of the extinguishant pressure rupturing the diaphragm 49.

On opening of the backing plate, the lug 60 engages a resilient buffer 64, and the other, nowangled, limb 65 acts to deflect the discharging extinguishant to and through outlet conduit 66.

As in the first-described embodiment, the cable connection to the operating shaft 57 and also the protector 62 which drives lug 63 are in a chamber 67 closed by cover 68 but isolated from the highpressure discharge of extinguishant which passes through the casing 50.

Figure 7 illustrates a discharge unit 70 which is functionally similar to those described above.

However, the diaphragm 71, which is clamped between casing 72 and port member 73, is flat and supported by a backing piston 74. The piston is held in its support portion by its rod 75 engaging a toggle 76 which is in turn held by the shorter arm of a lever 77. The longer arm of the lever 77 is held by the lower one of a pair of spaced rollers 78 which are held apart by a separator 79 carried at the end of a retractable cylinder 80. To release the piston, the cylinder 80 is shifted (to the left as viewed) by a lever 81 spring-loaded against stop 82, to retract the separator and so allow the rollers 78 to move together; the lower roller displaces upwardly to release the lever 77 which releases toggle 76 to free the piston rod.The piston is driven down by the extinguishant pressure bursting the diaphragm 71 which is formed with lines of weakness, and the discharging extinguishant escapes from outlet chamber 83 through an outlet port (not shown).

The cylinder 80 also accommodates an explosive retractor (not shown) to provide for alternative (electrical) operation of the release mechanism. The lever 77 engages the lower roller 78 through an abutment carried at the end of a screw 84 which extends through a tapped opening in the lever to be adjustably held by a lock-nut. Also, in this embodiment, the port member 73 is provided with a connector opening 86 for charging an empty container or monitoring a charged container. As shown, the connector is closed by a plug 87 and this plug may incorporate a pressure-relief facility.

In Figure 7, the mechanism for the release of the piston is accommodated in a chamber 88 which is isolated from the high-pressure flow of discharging extinguishant.

Figures 8 and 9 show alternative arrangements for the diaphragm which seals the venting port.

These alternatives are illustrated as applied to the embodiment illustrated in Figures 1 to 4, but may be adapted for use in the embodiments illustrated in Figures 5, 6 and 7.

In Figure 8, the clamping ring 89 is of increased length to permit the application of a standard spanner to flats 90 of the ring, and the dishing of diaphragm 91 is correspondingly increased. The port member 92 is shown as being formed with an annular rib 93 to promote hermetic sealing, as are the port members 1 3 and 52 and a ring 94 (similar to ring 45 in Figure 1) is also provided.

In Figure 9, the diaphragm 95 is flat, as is diaphragm 71 in Figure 7, and is sandwiched between a plate ring 96 and the face of port member 97 which carries a sealing O-ring 98 in an annular recess 99. The port member 97 is secured to casing 100 by bolts (not shown) and so a ring such as 48 or 94 is not required. However, it is important that the opening in the ring 96 closely matches the circumference of plate 101 which is formed on the top of the support member 102 to minimise the danger of the diaphragm material creeping into a space between these two peripheries.

Reference 102 denotes a backing plate catch in both of these Figures.

Referring now to Figures 10 to 14 of the drawings, there is shown a further embodiment of the invention, comprising a casing 11 2 to which a port member 11 3 is secured by means of fastening bolts 114. Between the casing 112 and the port member 11 3 there is arranged an intermediate mounting plate 11 5 which is secured to the casing 112 by way of fixing screws 11 6.

The port member 113 and the mounting plate 11 5 define co-operating clamping surfaces between which, as shown more clearly in Figure 13, is clamped a frangible metal diaphragm 117.

The diaphragm 11 7 is formed of a metal, such as aluminium, which is readily plastically deformable, so that when clamped between the mounting plate 11 5 and the port member 113 by means of the securing bolts 114, the diaphragm 117 forms a seal which is effectively proof against leakage of pressurised fire extinguishant from a container, such as that indicated diagrammatically in broken lines at 111 in Figure 11, the mouth of which is closed by a screw-threaded portion 11 8 of the port member 113. In order to promote a more effective seal by means of the diaphragm, the clamping surface of the port member 113 comprises a raised annular rib 11 3A arranged to cooperate with a corresponding annular groove 11 so of the plate 115, in order to deform a corresponding annular area of the aluminium diaphragm 117.The annular rib 11 3A and the corresponding groove 11 5A each has a crosssection of generally V-shaped configuration, but the section of the rib 11 3A is of shallower angle and of greater width than the groove 11 SA, so that the diaphragm 11 7 becomes pinched and plastically deformed between the flanks of the rib 11 3A, and the edges of the groove 11 5A. This plastic deformation of the diaphragm is sufficient to eliminate any avoids between the diaphragm and the clamping surfaces due to surface imperfection or irregularities, and thus ensures an effective seal.

The diaphragm 117 is provided with lines of weakness 11 8 (see Figure 12) which, as in the previously described embodiments, serve to promote controlled rupturing of the diaphragm.

The lines of weakness 11 8 are provided on that side of the diaphragm facing the contents of the container 11, and the opposite surface of the diaphragm is supported by means of a backing plate 11 9 which is pivotally mounted on a shaft 1 20 and held on the side opposite the shaft 120 by means of a pivoted lever 121 having a latching portion 121 A which engages and retains the backing plate 119. As in the case of the previous embodiment, the backing plate 119 may be provided with a hardened insert, not shown in Figure 10, in the region which engages the portion 121 A. The lever 121 is retained in latching engagement with the backing plate 119 by means of a roller 122 which engages between a recess 121 B of the lever 121, and a similar recess 1 23A of a further lever 123.

As shown more clearly in Figure 11 , the lever 121 is pivoted on a shaft 124 which is fixed in a corresponding bore provided in the housing 112.

As can be seen more clearly from Figure 12, the lever 123 is secured to a shaft 125 journalled in bearings 126 which may advantageously be roller bearings provided in the casing 112. The shaft 125 is additionally provided with O-ring seals 127 for the purpose described below.

The casing 112 comprises a discharge port 130, see Figure 13, which, in the condition of use is open to the area intended to be protected by the fire extinguisher, but, as illustrated in Figure 1 3 is closed by means of a screw-threaded plug 131 providing a safety cover in the event of inadvertent actuation of the fire extinguisher device during storage and/or transport. The plug 113 may, for example, comprise opposed radially extending bores, of which one is indicated at 132 in Figure 13, communicating with a central axial bore 133, to provide for a controlled release of extinguishant at a reduced rate and without recoil.The venting port 130 is closed by means of a secondary burstable diaphragm 134, which comprises an integral locking ring 135 which may be clamped in place by means of a plurality of radially extending grub screws, of which one is shown at 136 in Figure 13, screw-threaded into the wall of the port 130. Alternatively, the secondary diaphragm 134 may be secured by other means, as described above.

It will be seen that between the two diaphragms 117 and 134 there are defined by the casing 112, on the one hand a chamber 140 containing the pivoted backing member 119, and on the other hand a chamber 141 containing the pivoted levers 121 and 123. The chamber 141 is closed by means of a cover plate 142 securely bolted to the casing 112, the cover plate 142 being designed to withstand pressure of extinguishant to which the chamber 141 will be subjected during actuation of the extinguisher.

As can be seen from Figure 11 the chamber 114 comprises two opposite walls 141 A and 141 B which serve to provide axial location of the levers 121 and 123. The roller 122 is constrained by means of a cage defined by two opposed plates 143 comprising elongated slots 144 which allow limited movement of the roller 122 relatively to the lever 123. The roller 122 has at each end a spring clip 128 retaining it against axial movement.

The lever 123 is spring urged towards the position wherein the roller 122 can engage lever 121, by means of a leaf spring 145.

A buffer 146 of resilient material is secured to a wall of the chamber 140 in order to cushion impact by the backing plate 11 9, and likewise a buffer 147 is secured to a wall of chamber 141 in order to cushion impact by the lever 121.

As shown more clearly in Figure 13, a locking pin 1 48 is secured to a shaft 149 pivoted in the casing 112 and a head portion 1 50 of the shaft 149 which is accessible externally of the casing 112 comprises a hexagonal socket 51 by means of which the locking pin 148 may be pivoted manually from the position shown in Figures 10 and 13, in which it provides a safety lock for retaining the backing plate 11 9 in the closed position, to the position shown in broken lines in Figure 14. The locking pins 148 can be fastened in each of the two positions by means of a locking screw 1 52 or a spring loaded detent secured in the casing 112 and arranged to engage the shaft 149.

As shown in Figures 10, 11 and 13, the port member 113 is provided with a union 160, and with a number of threaded bores 161,which communicate with the interior of container 111.

These serve for the connection to container 111 of a pressure gauge and pressure sensors, which may serve for the monitoring of the state of the fire extinguisher as described below.

Referring now to Figures 12 and 14, it will be seen that the shaft 125 of lever 1 23 extends into a further chamber 1 63 defined by the casing 11 2, which chamber contains, on the one hand, an actuating lever and on the other hand an electrical actuator 1 66 having an extendible plunger 167.

The actuator 1 66 may either, as in the case of previously described embodiment, comprise a pyroelectric actuator, or may comprise a solenoid. An end of the shaft 125 extending into the chamber 1 63 carries a double rocker arm 169, of which one arm 1 70 engages the lever 164, and the other arm 1 71 engages the plunger 1 67 of the electric actuator 1 66.

It will be appreciated that since the chamber 163 is sealed from the chamber 141 by means of the shaft seals 1 27 provided around the shaft 125, the chamber 1 63 is not subjected to the same elevated pressure of extinguishant as are chambers 140 and 141, during discharge of the extinguisher, and thus it is not necessary for the chamber 1 63 containing the actuator 1 66 to be proof against elevated pressures. Thus, the chamber 1 63 may be closed by a simple cap 1 72 including an electrical connector 173 providing for connection of an external electrical actuating circuit to the actuator 1 66. A further cover plate 174 is also provided for the chamber 163.

As shown in Figures 10, 12 and 14, the shaft 1 65 of lever 1 64 extends through the casing 112 and carries, externally of the chamber 163, a further lever 1 75 which may be connected to a manually operable actuating linkage. As shown in Figure 14, the lever 175 and the casing 112 may comprise cooperating apertures 1 76 and 177, enabling the lever 175 to be locked in an inoperative position by means of a cotter pin, or the like, during storage or transport of the extinguisher.

The operation of the device illustrated in Figures 10 to 14 is as follows. When the extinguisher is charged ready for use, the components will be set in the positions shown in Figures 10 to 13. Thus the charged container 111 is closed by the diaphragm 11 7 which is turn supported by the pivoted backing plate 11 9. The union 1 60 is connected to a pressure gauge indicating the state of readiness of the charged container, and any one or more of the threaded bores 161 may receive a pressure sensor device, or alternatively may be closed by an appropriate blanking plug.The backing plate 11 9 is locked in the closed position by means of the locking pin 148, and is additionally latched by means of the lever 121, the lever 123 being spring urged by means of the leaf spring 145 into the position wherein the roller 122 engages between the cooperating recesses of the two levers 121 and 123. The cage provided by the two plates 143 does not itself provide support for the roller 122, but merely constrains the roller against escape from the lever 123 when the extinguisher is in the released state. The manual actuating lever 1 75 is locked in position by means of a cotter pin engaging holes 176 and 177, and the venting port 130 is closed by means of the safety plug 131.

The extinguisher unit is thus maintained in a safe condition. In addition, the leaf spring 145 guards against casual displacement of the lever 123 and thus renders the extinguisher shockproof.

Upon installation of the extinguisher in its position of use, it is prepared for operation by removal of the cotter pin securing lever 175, removal of the anti-recoil security plug 131, and rotation of the locking pin 148 into the idle condition. The lever 175 is coupled to its manual actuating mechanism, and the electrical actuator 1 66 is electrically connected to the corresponding actuating circuit. Any pressure sensors provided in the bores 161 may be coupled to a corresponding control circuit, for example a logic circuit utilised for controlling and/or selecting actuation of groups of fire extinguishers in response to the sensed condition of individual extinguishers.

When the extinguisher is in its condition of readiness, all of the mechanical and electrical actuating components are effectively sealed from ambient atmosphere within the respective chambers 140,141 and 163, and thusthe extinguisher is resistant to harsh conditions for prolonged periods of time. Although not indicated in the drawings, the shaft 1 65 may be provided with shaft seals, like the shaft 125, for more effective sealing of the chamber 1 63.

Upon actuation of the extinguisher, either by mechanical actuation of the lever 175, or by electrical actuation of the actuator 1 66, the shaft 125 is rotated by way of the corresponding rocker arm 170 or 171 to pivot the lever 123. The roller 1 22 is thus caused to roll between the opposed surfaces of the lever 123 and the lever 121, until it escapes from the recess of the lever 1 21, and releases the latter without the requirement for any sliding friction. Upon the release of the lever 121 the backing plate 119 is caused to pivot, under pressure applied to the diaphragm 117, until, upon bursting of the diaphragm 117, the pressurised extinguishant can escape into the chamber 1 40 to burst the secondary diaphragm 1 34 and escape through the venting port 1 30.

During escape of the extinguishant, the backing plate 11 9 and lever 121 are propelled at high velocity into the conditions shown in broken lines in Figure 14, their impact against the walls of casing 112 being cushioned by way of the buffers 146 and 147.

After actuation, the extinguisher, can be prepared for re-use by replacement of the diaphragms 11 7 and 134, and return of the actuating mechanism to its latched condition. If desired, the backing plate 119 and lever 121 may be lightly spring loaded, by means not shown, in order to assist resetting of the mechanism. The container 111 may then be recharged with extinguishant.

Claims (21)

1. A fire extinguisher device comprising a container of pressurised fire extinguishant, a burstable diaphragm closing an orifice of said container, an external backing member supporting said diaphragm against bursting thereof by the pressure of said extinguishant, and a mechanism for retaining said backing member in contact with said diaphragm, said mechanism being actuatable to release said backing member and allow bursting of the diaphragm whereby extinguishant from said container becomes discharged through a venting port, wherein said mechanism includes an abutment member making rolling contact with a counter surface against which pressure is exerted thereby to transmit support to said backing member, and means for transmitting rolling motion to said member to release it from said counter surface.

2. A device as claimed in Claim 1, wherein said backing member is supported by a pivoted lever member having a free end which engages with said roller member.

3. A device as claimed in Claim 1, wherein the said backing member comprises an angled member of which one end is mounted on a pivot adjacent said diaphragm and the other end engages directly against said abutment member.

4. A device as claimed in Claim 1, wherein the said backing member comprises a central, axially extending rod member which is supported for axial sliding movement within a housing portion defining said venting port, and a free end of said rod member is retained by a lever mechanism including a lever of which a free end defines said counter surface.

5. A device as claimed in Claim 4, wherein said abutment member is one of a pair of rollers of which the other engages a fixed abutment surface of the extinguisher, and the said means for transmitting said rolling motion comprises a removable plunger member arranged to penetrate between the two rollers.

6. A device as claimed in any one of Claims 1-3, wherein the said actuating mechanism includes a rotary shaft supported in a partition wall of a housing separating the flow path of extinguishant from a chamber containing at least one actuating means for each mechanism, said rotary shaft carrying on one side of said partition, at least one rocker arm arranged within said chamber to cooperate with a corresponding actuating means, and carrying, on the other side of said partition, the said abutment member.

7. A device as claimed in Claim 6, wherein the portion of said rotary shaft extending through said partition wall is provided with a shaft seal for sealing said chamber against penetration by said extinguishant.

8. A device as claimed in Claim 1 or 2, wherein the said backing member comprises a central relief bore extending away from said diaphragm and communicating with said venting port, the end of said bore adjacent said diaphragm having radiussed edges.

9. A device as claimed in Claim 6, wherein said chamber is hermetically sealed.

10. A device as claimed in any one of Claims 6, 7 or 9, wherein said chamber contains an electrically triggerable actuator arranged to act upon a rocker arm of said shaft.

11. A device as claimed in Claim 10, wherein said actuator comprises a pyroelectric device.

12. A device as claimed in Claim 10, wherein said actuator comprises a solenoid.

13. A device as claimed in any one of Claims 6, 7 or 9-12, wherein said chamber further comprises a lever arranged to act upon a further rocker arm of said shaft and coupled to an actuating mechanism outside said chamber.

14. A device as claimed in any one of Claims 1-3 or 6-1 3, wherein the said abutment member comprises a roller, and the said means for transmitting rolling motion to said abutment member comprises a rotary shaft carrying a cage within which the two ends of said roller are supported.

1 5. A device as claimed in Claim 14, wherein the said cage comprises a pair of elongate slots allowing relative movement between the axis of the roller and the cage, and the said rotary shaft further carries a supporting surface arranged to engage and hold said roller against said counter surface, whereby, whilst constrained by said cage, the roller can roll between said supporting surface and said counter surface during actuation of the said mechanism.

1 6. A device as claimed in any one of Claims 1-1 5, wherein there is provided in the flow path of extinguishant from said burstable diaphragm to said venting port, a second burstable diaphragm providing a secondary seal enclosing said backing member and any associated components of said actuating mechanism.

17. A device as claimed in any one of Claims 1-1 7, wherein said diaphragm is clamped at its periphery and is formed with lines of weakness which extend outwardly from the centre of the diaphragm and which promote bursting of the diaphragm into segments which are held at their roots against detachment from the clamped periphery of the burst diaphragm.

1 8. A fire extinguisher substantially as described herein with reference to Figures 1-3 of the accompanying drawings.

1 9. A fire extinguisher device substantially as described herein with reference to any one of Figures 4-6 or 7-9 of the accompanying drawings.

20. A fire extinguisher device substantially as described herein with reference to any one of Figures 10-14 of the accompanying drawings.

21. The features as herein described, or their equivalents, in any novel selection.