Pyrotechnic valve

Abstract

There is provided a valve for controlling the release of fire suppressant from a pressurized container, said valve comprising a diaphragm configured to perforate upon action of a shockwave directed onto the surface of said diaphragm, a pyrotechnic charge arranged and adapted to combust to produce combustion products that form a shockwave directed onto the surface of said diaphragm, and a device encasing said pyrotechnic charge. The device comprises a hollow, elongate channel located over said pyrotechnic charge and directed at the center of said diaphragm so as to focus or direct said combustion products onto the center of said diaphragm. The elongate channel has a length that is at least 1.5 times its smallest width.

Claims

1. A valve configured to plug and seal a pressurized container and for controlling the release of fire suppressant therefrom, said valve comprising: a diaphragm configured to perforate upon action of a shockwave directed onto a surface of said diaphragm; a pyrotechnic charge arranged and adapted to combust to produce combustion products that form a shockwave directed onto the surface of said diaphragm; a device encasing said pyrotechnic charge and comprising a hollow, elongate channel located over said pyrotechnic charge and directed at a center of said diaphragm so as to focus or direct said combustion products onto the center of said diaphragm; and a passage for fire suppressant to travel through, wherein said passage extends from a valve inlet to a valve outlet, wherein upon perforation of said diaphragm fire suppressant travels through said passage from said valve inlet to said valve outlet, and said diaphragm, pyrotechnic charge and device are all located within said passage; wherein said elongate channel has a length that is at least 1.5 times its smallest width; wherein said diaphragm comprises a plurality of score lines that define portions of said diaphragm that will tear open upon action of a shockwave directed onto the surface of the diaphragm; and wherein said device comprises a hollow tube comprising the elongate channel and having an outlet end located at an end of the elongate channel located towards the diaphragm and away from the pyrotechnic charge, wherein the outlet end of the hollow tube is chamfered to prevent one of said portions of said diaphragm touching said tube upon opening.

2. A valve as claimed in claim 1, wherein said device is a single piece comprising a lower portion comprising a first diameter and holding the pyrotechnic charge, and an upper portion comprising said elongate channel, wherein said elongate channel comprises a second diameter, and the second diameter is smaller than the first diameter.

3. A valve as claimed in claim 1, wherein said diaphragm is configured to perforate such that portions of said diaphragm open outward and towards said pyrotechnic charge.

4. A valve as claimed in claim 1, wherein said pyrotechnic charge comprises a cap or cover enclosing a combustible material, wherein said cap or cover is separate to said device encasing said pyrotechnic charge.

5. A valve as claimed in claim 4, wherein said device is configured to stay intact upon activation of said pyrotechnic charge.

6. A valve as claimed in claim 1, wherein said device is metallic or ceramic.

7. A valve as claimed in claim 1, wherein said combustion products comprise primarily gaseous matter.

8. A valve as claimed in claim 1, wherein said combustion products do not comprise solid fragments of said pyrotechnic charge.

9. A valve as claimed in claim 1, wherein said diaphragm is located a distance from said pyrotechnic charge, wherein said distance is sufficient to allow portions of said diaphragm to open at least 45 degrees upon perforation thereof.

10. An apparatus comprising: a pressurized chamber having fire suppressant therein and having an outlet; a valve as claimed in claim 1, wherein said valve seals said outlet of said chamber so as to control the release of fire suppressant therefrom, wherein said valve inlet seals against the outlet of the pressurized chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments of the present disclosure will now be described, together with an example given for illustrative purposes only, and by way of example only, and with reference to the accompanying drawings in which:

(2) FIGS. 1A-1C show a conventional apparatus comprising a chamber holding a fire suppressant and a valve for controlling release of fire suppressant from the chamber;

(3) FIG. 2 shows an embodiment of the present disclosure;

(4) FIG. 3A shows an embodiment of the present disclosure; and

(5) FIG. 3B shows a further embodiment of the present disclosure; and

(6) FIG. 4 shows an embodiment of the present disclosure after rupture of the diaphragm; and

(7) FIG. 5 shows an example diaphragm including example score marks.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

(8) An embodiment of the present disclosure will now be described with reference to FIG. 2, which shows an apparatus including a container 100 and a valve 200.

(9) The container 100 is of the type used to hold a fire suppressant (not shown) in its interior, optionally in powder form, and is largely cylindrical, forming a bottle-shape with an outlet 120 (which may be the only outlet) provided at a lower end of the container 100. The container 100 comprises a neck portion 102 and a chamber portion 103. The chamber portion 103 has a maximum diameter that is relatively large when compared to the diameter of the neck portion 102, and forms the main body of the container 100 for holding most of the fire suppressant. The neck portion 102 and the outlet 120 are of a smaller diameter.

(10) The interior of the container is pressurised, for example using nitrogen gas. The valve 200 is inserted into the outlet 120 so as to plug or seal the container 100 and prevent pressurised fire suppressant held within the container from being released prematurely. Other shapes of container may be used, and the disclosure is not limited to cylindrical containers such as the one shown.

(11) The valve 200 comprises a valve body 220 that is hollow and forms a passage 222 for fire suppressant to transfer from the interior of the container 100 to the environment. The passage 222 extends from a valve inlet 223 to a valve outlet 224. The valve inlet 223 and a neck 226 of the valve body 220 fit within the outlet 120 of the container 100, and a shoulder portion 228 of the valve body 220 rests on an exterior surface of the container 100. The valve inlet 223 and neck 226 are sealed against the walls of the neck portion 102 and outlet 120 of the container 100. Any suitable sealing method may be used.

(12) The apparatus includes a rupturable diaphragm 130 that is positioned within the passage 222 of the valve body 220. The diaphragm 130 is sealed against the interior walls of the passage 222 and valve body 220 so as to prevent the fire suppressant from being released through said passage 222.

(13) A pyrotechnic charge 140 is provided and arranged such that, upon activation of the charge, a shockwave, or percussive wave, is directed onto the diaphragm 130 by the rapid release of gas and heat generated by the pyrotechnic charge 140. This kind of charge may be termed a gaseous charge. This causes the diaphragm 130 to flex, weaken and perforate (or burst, fail, tear etc.). Due in part to the pressure differential across the diaphragm 130 when the container 100 is pressurised, the diaphragm 130 perforates outwards away from the chamber portion 103 and fire suppressant as shown in FIG. 4.

(14) This gaseous mechanism is different from, say, an explosive or fragmenting charge that uses fragments of hot metal to perforate a diaphragm. Optionally, the pyrotechnic charge does not expel fragments of metal upon activation. The shockwave is optionally comprised primarily of gaseous matter.

(15) After perforation of the diaphragm 130, fire suppressant transfers from the interior of the container 100 to the external environment (e.g. a fire suppressant system for a building or transport vehicle such as an aircraft) via passage 222. This is due, in part, to the fire suppressant being held under pressure within the container 100.

(16) The diaphragm 130 is typically made of metal, for example stainless steel or nickel. The diaphragm 130 may be scored across its surface to promote failure of the diaphragm 130 along predefined score lines as shown in FIG. 5. The score lines 500 may form a star pattern on the surface of the diaphragm 130, causing the diaphragm 130 to petal open along the predefined score lines. For example, six radial score lines may be provided, each starting at the top of the diaphragm 130 and ending at the circumference. The score lines may be equally spaced around the circumference of the diaphragm 130. It will be appreciated that the valve 200, including the diaphragm, pyrotechnic charge and device may be removable and/or replaceable as a single unit.

(17) As shown in FIG. 2 the diaphragm 130 is hemispherical and the tip of the hemisphere points towards the pyrotechnic charge 140, and away from the container 100 and chamber portion 103.

(18) In accordance with the present disclosure, a device 150 is located over and/or around the pyrotechnic charge 140 so as to encase it, and is configured to focus the shockwave onto the centre of the diaphragm 130. It has been found that some pyrotechnic charges of the gaseous type (rather than the fragmenting type) have not been sufficient to cause the diaphragm 130 to open. Focusing the combustion products onto the centre of the diaphragm 130 using a device 150 as described herein maximises the energy applied to the diaphragm 130 by the combustion products, and decreases the energy lost to the environment, e.g. walls of the passage 222.

(19) FIG. 3A shows the pyrotechnic charge 140 and the device 150 in more detail.

(20) The device 150 in the illustrated embodiment is in the form of a hollow tube or cylinder having a lower portion 152 and an upper portion 154.

(21) The lower portion 152 is tubular and has a relatively large inner diameter. The pyrotechnic charge 140 is located within the lower portion 152 having the relatively large inner diameter. The pyrotechnic charge 140 may comprise a cap or cover. This means that a small portion of the energy produced by the pyrotechnic charge 140 may be required to rupture or break the cap or cover. However, such a cap or cover would optionally be distinct from the device 150 and its elongate channel 155. Other embodiments are contemplated in which the device forms the cap or cover for a combustible material, in which case the pyrotechnic charge may consist or, or consist essentially of a combustible material.

(22) The upper portion 154 of the device 150 is also tubular and has a relatively small inner diameter so as to provide an elongate channel 155 for combustion products to pass through upon activation of the pyrotechnic charge. The elongate channel directs the combustion products onto the centre of the diaphragm 140. The elongate channel 155 has a length that is at least 1.5 times its diameter, and optionally at least 2, 3, 4 or 5 times its diameter.

(23) The device is most effective when the charge is directed onto the centre of the diaphragm, since the centre is always the weakest part of the diaphragm when subjected to the internal pressure from the cylinder. Using a device 150, especially a device 150 comprising an elongate channel 155 as described herein, provides the optimum conditions for rupturing the diaphragm 130.

(24) The device is most effective when the charge is directed onto the centre of the diaphragm, since the centre is typically the weakest part of the diaphragm when subjected to the internal pressure from the interior of the container 100. A device 150 comprising an elongate channel 155 as described herein provides the optimum conditions for rupturing the diaphragm 130 using a pyrotechnic charge.

(25) The device 150 may reduce the energy requirements of a given pyrotechnic charge. For example, using the conventional arrangement of FIGS. 1A-1C, a given shockwave produced by a pyrotechnic charge may not transfer sufficient energy to the diaphragm 30 to open it. Using the arrangement of FIG. 2, the shockwave produced by the same pyrotechnic charge 140 will have the same energy, but it will be focused onto the centre of the diaphragm 130 by the device 150, and the diaphragm 130 will tear open, for example along the predefined score lines.

(26) The device 150 is located a sufficient distance from the diaphragm 130 such that the diaphragm 130 can fully open upon activation of the pyrotechnic charge 140. For example, upon perforation of the diaphragm 130 it will petal open along the predefined score lines, and the tips of the petals will not clip or touch an end 156 of the device 150 as they travel past.

(27) The device 150 does not substantially combust, fragment or break upon activation of the pyrotechnic charge 140. That is, the device 150 stays substantially intact upon activation of the pyrotechnic charge 140. The device 150 may be made of metal to achieve this, although other materials could be used, such as a ceramic.

(28) An alternative embodiment is shown in FIG. 3B. This embodiment is identical to that of FIGS. 2 and 3A, expect that a different device 250 is provided.

(29) In this embodiment, the end 256 of the device 250 located towards the diaphragm 130 comprises a chamfered outer circumference 258, or chamfer. This allows a minimum distance to be provided between the end 256 of the device 250 and the diaphragm 130, since the chamfer 258 allows more room for portions of the diaphragm 130, for example petals, to pass through when the diaphragm 130 is ruptured upon activation of the pyrotechnic charge.

(30) With respect to the remaining features of the device 250, these are substantially the same as those of the device 150 of FIG. 3A and have been denoted with like reference numerals accordingly, but with 100 added to each number.

(31) Although the present disclosure has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the disclosure as set forth in the accompanying claims.