GAS GENERATOR FIRE SUPPRESSION SYSTEM

Abstract

A solid propellant gas generator fire suppression device 6 is disclosed comprising: a solid propellant material for generating a first fire suppression gas when combusted; an ignitor 10 for igniting the solid propellant material so as to generate said gas; an exhaust 12 for said gas; and an odorizer material arranged within the gas generator so that when the ignitor 10 is activated the odorizer material, or an odorous product thereof, exits the gas generator 6 through the exhaust 12.

Claims

1. A solid propellant gas generator fire suppression device comprising: a solid propellant material for generating a first fire suppression gas when combusted; an ignitor for igniting the solid propellant material so as to generate said gas; an exhaust for said gas; and an odorizer material arranged within the gas generator so that when the ignitor is activated the odorizer material, or an odorous product thereof, exits the gas generator through the exhaust.

2. The gas generator of claim 1, comprising a smoke and/or heat detector and/or flame detector and/or gas detector coupled to said ignitor and configured such that when said detector detects smoke and/or heat and/or flames and/or gas the ignitor is activated so as to ignite the solid propellant material.

3. The gas generator of claim 1, wherein the exhaust comprises at least one pair of exhaust nozzles or vents, wherein each pair comprises nozzles or vents on opposing sides of the exhaust such that when the gas exits the exhaust it generates substantially no net force on the exhaust.

4. The gas generator of claim 1, wherein the odorizer material is mixed in with the solid propellant material.

5. The gas generator of claim 1, wherein the odorizer material is solid, such as a powder.

6. The gas generator of claim 1, wherein the odorizer material contains sulphur; optionally wherein the odorizer material or odorous product comprises sulphur dioxide or sulphides.

7. The gas generator of claim 1, wherein the odorizer material is arranged within the gas generator such that, upon activation of the ignitor and/or combustion of the solid propellant material, the odorizer material reacts with another compound present in the generator so as to produce said odorous product.

8. The gas generator of claim 1, wherein the odorizer material is arranged within the generator such that it, or said odorous product, becomes entrained in the gas as the gas travels towards the exit of the exhaust.

9. The gas generator of claim 1, wherein the odorizer material is provided within a chamber inside the gas generator, optionally in a different chamber to the solid propellant material.

10. The gas generator of claim 1, further comprising a seal for preventing the odorizer material from leaving the gas generator or chamber until the ignitor is activated.

11. A fire suppression system comprising: a gas generator that includes: a solid propellant material for generating a first fire suppression gas when combusted; an ignitor for igniting the solid propellant material so as to generate said gas; an exhaust for said gas; and an odorizer material arranged within the gas generator so that when the ignitor is activated the odorizer material, or an odorous product thereof, exits the gas generator through the exhaust; and a storage tank for storing a fire suppression material; wherein the exhaust of the gas generator is arranged within the storage tank.

12. The fire suppression system of claim 11, wherein the storage tank comprises a valve for allowing fire suppressant to exit the tank when the pressure inside the tank is at or above a predetermined level.

13. A fire suppression system comprising: a storage tank for storing a fire suppression material; a chamber housing an odorizer material arranged within the storage tank; a solid propellant gas generator having an ignitor and an exhaust, wherein the exhaust is arranged within the storage tank.

14. The system of claim 13, wherein the chamber comprises a seal for preventing the odorizer material leaving the chamber until the ignitor is activated.

15. The system of claim 13, wherein the exhaust is configured to direct combustion gases from the gas generator exhaust onto and/or through the chamber, e.g. so as to release or drive the odorizer material from the chamber and into the storage tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings in which:

[0044] FIG. 1 shows a solid propellant gas generator fire suppression device according to an embodiment of the present invention;

[0045] FIG. 2 shows a solid propellant gas generator fire suppression device according to another embodiment of the present invention; and

[0046] FIG. 3 shows a solid propellant gas generator fire suppression device according to another embodiment of the present invention

DETAILED DESCRIPTION

[0047] FIG. 1 shows a schematic of a portion of a fire suppression system according to an embodiment of the present invention. The system comprises a gas cylinder 2 that houses inert gas 4, such as nitrogen, for use in suppressing a fire. The cylinder 2 also houses a solid propellant gas generator 6 for use in generating an inert gas. The gas generator 6 comprises pellets of solid propellant material (e.g. sodium azide), an ignitor 10, gas exhaust vents or nozzles 12, and optionally a filter. The gas generator 6 also comprises an odorizer compound for providing a detectable odour to human personal when the system is discharged. The odorizer compound may be provided as a solid within the pellets of propellant material, or may be provided in the gas generator separate to the pellets. The cylinder 2 further comprises a burst disc 14 and discharge piping 16.

[0048] When the fire suppression system detects a potential fire, e.g. via a heat and/or smoke detector, the ignitor 10 in the gas generator 6 is activated and generates heat. This ignites the solid propellant material and initiates the combustion thereof, thereby generating inert combustion gas (and potentially also some particulate matter). The inert combustion gases exit the gas generator 6 through the exhaust vents or nozzles 12 in an exhaust and pass into the main body of the cylinder 2. The vents or nozzles 12 may be arranged so as to negate any net force on the exhaust caused by the flow of the gas. For example, the vents or nozzles 12 may be arranged in pairs on the exhaust, with one vent or nozzle of the pair on one side of the exhaust and another vent or nozzle of the pair on the opposing side of the exhaust. The vents or nozzles 12 may also be arranged so as to promote mixing of the gases exhausted from the gas generator 6 with the other gas initially stored in the main body of the cylinder 2. This serves to cool the hot gas exhausted from the gas generator 6. It will be appreciated that ratio of the quantity of gas generated by the gas generator 6 to the quantity of gas initially stored in the main body of the cylinder 2 may be selected during design of the system such that the mixed gas has the desired temperature when discharged.

[0049] If a filter is present in the gas generator 6 then this filter prevents particulate matter from exiting the gas generator 6 into the main body of the cylinder 2. The gas passing from the gas generator 6 into the main body of the cylinder 2 causes the gas pressure inside of the main body of the cylinder 2 to rise. The burst disc 14 is configured to seal the gas inside the main body of the cylinder 2 until that gas reaches a predetermined pressure. Once the gas inside the main body of the cylinder 2 has risen above this predetermined pressure, the gas overcomes the burst disc 14 and passes through the discharge piping 16 to the area to be protected from fire. The inert gas may then dilute the oxygen concentration in the area to be protected such that a fire in that area is suppressed or prevented from being established.

[0050] As mentioned above, the gas generator 6 also includes an odorizer compound. The odorizer compound is confined within the gas generator 6 until the ignitor 10 has been activated, at which point the odorizer compound may be converted from a solid phase (or less desirably a liquid phase) to a gaseous phase, or may react with another compound present in the gas generator 6 so as to generate another compound having a discernible smell. For example, the odorizer compound may be converted to the gaseous phase by the heat from the ignitor 10 or by the combustion of the solid propellant material. It is contemplated that the odorizer material may be a compound in solid form that is included within the solid propellant material, e.g. within a pellet of solid propellant material. For example, sulphur or its derivatives may be mixed in with the solid propellant material such that when the propellant material combusts, sulphur dioxide and/or sulphides (e.g. small volatile sulphides) are generated. Alternatively, it is contemplated that the odorizer compound may remain in a solid phase (or less desirably a liquid phase) during and after combustion of the solid propellant material, but may become entrained in the combustion gas as it flows towards and out of the exhaust.

[0051] The odorizer compound may be a compound that itself has a smell that is discernible to humans. Alternatively, the odorizer compound may be a compound that itself has no discernible smell, but that reacts with another compound present in the gas generator 6, upon activation of the ignitor 10, so as to generate another compound having a smell that is discernible to humans.

[0052] In the embodiments described above, activation of the ignitor 10 causes the odorizer compound itself, or a product thereof, to become entrained in the combustion gas that flows out of the exhaust vents or nozzles 12 and into the gas in the main body of the cylinder 2. As such, when the gas is discharged from the cylinder 2 into the area to be protected, the discharged gas will have an odor that is detectable to humans entering the area to be protected, even if the gas initially held within the main body of the cylinder 2 has no discernible smell (e.g. nitrogen). Personnel entering the area to be protected are therefore able to determine from the smell in that area that the fire suppression system has been discharged and that they are at risk from the low oxygen environment that is present.

[0053] FIG. 2 shows a schematic of an embodiment that is substantially the same as that of FIG. 1, except that the odorizer compound is provided in a chamber 18 that is separate from the chamber of the gas generator 6 that includes the solid propellant. The separate chamber 18 enables the odorizer compound to be shielded from the combustion of the solid propellant. The chamber 18 may be within the gas generator housing or attached to the outside of it. In either case, the odorizer compound may be sealed inside of chamber 18 until the gas generator 6 is activated. Activation of the ignitor 10 causes the odorizer compound to be released from the chamber 18. This may be achieved by a number of means. For example, if the chamber 18 is sealed the ignitor 10 may be configured to rupture the seal when the ignitor 10 is triggered. This may occur directly, e.g. by the ignitor activating an explosive or piercing member that opens the seal of the chamber 18. Alternatively, or additionally, the combustion gases generated by ignition of the solid propellant material may cause an increase in pressure or temperature that may rupture the seal. Whether the chamber 18 is sealed or not, the apparatus may be configured such that the combustion gases pass through the chamber 18. For example, chamber 18 may be provided adjacent to vents or nozzles 12. The combustion gases may convert the odorizer compound from a solid phase (or less desirably a liquid phase) to a gaseous phase, or may cause the odorizer compound to react with another compound present so as to generate another compound having a discernible smell. For example, the odorizer compound may be converted to the gaseous phase by the heat from combustion gases. Alternatively, it is contemplated that the odorizer compound may remain in a solid phase (or less desirably liquid phase), but may become entrained in the combustion gas as it flows through and out of chamber 18. It is also contemplated that the odorizer compound may initially be in a gaseous phase in chamber 18, and activation of the ignitor 10 may release the gaseous material.

[0054] After activation of the ignitor, the odorizer compound is released or driven into the main body of the cylinder and the system proceeds to discharge as described in relation to FIG. 1.

[0055] FIG. 3 shows a schematic of an embodiment that is substantially the same as that of FIG. 2, except that the chamber 18 is not part of or attached to gas generator 6. Rather, the chamber 18 is provided spaced apart from the gas generator in the main body of the cylinder 2. The odorizer material may be released from chamber 18 in any of the manners described in relation to FIG. 2.

[0056] The odorizer compound may be selected such that the compound, or product thereof, is a compound that is detectable by the human nose in concentrations of ppm or sub-ppm levels.

[0057] As described herein, the odorizer compound remains confined in the gas generator 6 or chamber 18 until the ignitor 10 has initiated, or only generates an odorous product when the ignitor 10 is initiated. This ensures that the odorizer compound or its odorous product do not enter the main body of the cylinder 2 until near to the time that gas is discharged into the area to be protected. As such, the odorizer compound or its odorous product are not stored in the main body of the cylinder 2 for long periods of time and hence do not leach into, or condense onto, the internal walls of the cylinder 2. The odorizer compound or its odorous product therefore remains fresh and pungent at the time of discharge, enabling less odorizer compound to be used in the system.

[0058] The odorizer compound, or the odourous product thereof, may be selected from a number of compounds. It will be appreciated that the odor of that compound should be sufficiently different from any odors that might normally occur within the area to be protected from fire. The compound may be a sulphur based chemicals such as thiols or mercaptans, sulfides or similar odorants. These are foul smelling stench agents. Other odorants that may be used include limonene, which has a pungent, sickly, orange smell.

[0059] The odorizer compound, or the odourous product thereof, may be an ester such as in the following table:

TABLE-US-00001 Compound Fragrance Natural occurrence Methyl formate Ethereal Methyl acetate Sweet, nail polish Solvent Methyl butyrate Fruity, apple, Methyl Butanoate Pineapple Ethyl acetate Sweet, solvent Wine Ethyl butyrate Fruity, orange Ethyl butanoate Pineapple Isoamyl acetate Fruity, banana Pear Pentyl butyrate Fruity, pear Pentyl butanoate Apricot Pentyl pentanoate Fruity, apple Octyl acetate Fruity, orange Fructone Fruity, apple-like Hexyl acetate Apple, floral, fruity Ethyl strawberry methylphenylglycidate

[0060] Alternatively, the odorizer compound, or the odourous product thereof, may be a terpene such as in the following table:

TABLE-US-00002 Compound Fragrance Natural occurrence Myrcene Woody, complex Verbena, bay Geraniol Rose, flowery Geranium, lemon Nerol Sweet rose, flowery Neroli, lemongrass Citral, lemonal Lemon Lemon myrtle, Geranial, neral lemongrass Citronellal Lemon Lemongrass Citronellol Lemon Lemongrass, rose Pelargonium Linalool Floral, sweet Coriander, sweet basil Woody, lavender Lavender Merolidol Woody, fresh bark Neroli, ginger Jasmine

[0061] Alternatively, the odorizer compound, or the odourous product thereof, may be a cyclic terpene such as in the following table:

TABLE-US-00003 Compound Fragrance Natural occurrence Limonene Orange Orange, lemon Camphor Camphor Camphor laurel Terpineol Lilac Lilac, cajuput Alpha-lonone Violet, woody Violet Thujone Minty Cypress, lilac, Juniper

[0062] Alternatively, the odorizer compound, or the odourous product thereof, may be an aromatic compound such as in the following table:

TABLE-US-00004 Compound Fragrance Natural occurrence Benzaldehyde Almond Eugenol Clove Clove Cinnamaldehyde Cinnamon Cassia, Cinnamon Ethyl maltol Cooked fruit Caramelized sugar Vanillin Vanilla Vanilla Anisole Anise Anise Anethole Anise anise, Sweet basil Estragole Terragon Terragon Thymol Thyme Thyme

[0063] Alternatively, the odorizer compound, or the odourous product thereof, may be an amine such as in the following table:

TABLE-US-00005 Compound Fragrance Natural occurrence Trimethylamine Fishy, Ammonia Putrescine Rotting flesh Rotting flesh Diaminobutane Cadaverine Rotting flesh Rotting flesh Pyridine Fishy Indole Faecal, flowery Faeces jasmine Skatole Faecal Faeces

[0064] Alternatively, the odorizer compound, or the odourous product thereof, may be an alcohol such as in the following table:

TABLE-US-00006 Compound Fragrance Natural occurrence Furaneol strawberry 1-Hexanol herbaceous, woody Cis-3-Hexen-1-ol Fresh cut grass Menthol peppermint

[0065] Alternatively, the odorizer compound, or the odourous product thereof, may be an aldehyde such as in the following table:

TABLE-US-00007 Compound Fragrance Natural occurrence Acetaldehyde ungent Hexanol Green, grassy Cis-3-Hexen-1-ol Green tomatoes Furfural Burnt oats

[0066] Alternatively, the odorizer compound, or the odourous product thereof, may be a ketone such as in the following table:

TABLE-US-00008 Compound Fragrance Natural occurrence Dihydrojasmone Fruity, woody, floral Oct-1-en-3-one Blood, metallic, mushroom-like 2-Acetyl-1-pyrroline Fresh bread, jasmine rice 6-Acetyl-2,3,4,,5- Fresh bread, tetrahydropyridine tortillas, popcorn

[0067] Alternatively, the odorizer compound, or the odourous product thereof, may be a lactone such as in the following table:

TABLE-US-00009 Compound Fragrance Natural occurrence Gamma- Intense peach Decalactone flavour Gamma- Coconut odour, Popular in suntan Nonalactone lotions Delta-Octalactone Creamy note Jasmine lactone Powerful fatty fruity peach and apricot Massoia lactone Powerful creamy coconut Wine lactone sweet coconut odour Sotolon Maple syrup, curry, fenugreek

[0068] Alternatively, the odorizer compound, or the odourous product thereof, may be a thiol such as in the following table:

TABLE-US-00010 Compound Fragrance Natural occurrence Furaneol strawberry 1-Hexanol herbaceous, woody Cis-3-Hexen-1-ol Fresh cut grass Menthol peppermint

[0069] Alternatively, the odorizer compound, or the odourous product thereof, may be a compound in the following table:

TABLE-US-00011 Compound Fragrance Natural occurrence Methylphospine & Garlic-metallic Two of the most dimethylphosphine potent odorants known Nerolin Tetrahydrothiophene 2,4,6-Trichloroanisole Substituted pyrazines

[0070] The fire suppression system described herein may be used to protect any environment that personnel may enter from fire, such as a cargo compartment. The personnel would be educated that if they smell the odorizer compound, or the odourous product thereof, that the fire suppressant has been discharged and that they should exit the area.

[0071] A solid propellant gas generator fire suppression device is disclosed comprising: a solid propellant material for generating a first fire suppression gas when combusted; an ignitor for igniting the solid propellant material so as to generate said gas; an exhaust for said gas; and an odorizer material arranged within the gas generator so that when the ignitor is activated the odorizer material, or an odorous product thereof, exits the gas generator through the exhaust.

[0072] The use of an odorizer material enables personnel to determine via their sense of smell that the fire suppression system has been discharged, and that they are at risk from being in a low oxygen environment. The odorizer compound, or odorous product thereof, may only become entrained in the gas and exit the gas generator (or another chamber) after the ignitor has been activated. The odorizer compound or its odourous product may remain fresh and pungent at the time of discharge and relatively low amounts of odorizer compound may be used in the system. The ignitor or the combustion of the solid propellant material may assist in generating and/or dispersing the odorizer material, or product thereof, in the gas exhausted from the system.

[0073] Although it is known to use odorizer compounds in fire suppression systems, it is believed that it is not known to add them into a gas generator or confine them in a chamber that is opened by activating the gas generator. Rather, such compounds have been arranged downstream of an inert gas cylinder discharge point. Furthermore, systems in which an odorizer compound is stored in a gas storage tank suffer from the problem that the odorizer compound may leach or condense onto the wall of its storage tank over time. Further, although gas generators have been disclosed previously that use sodium azide and sulphur, the sulphur in these devices is included as an oxidant for capturing the sodium and not for forming odorous compounds. In these devices, the sulphur remains in solid form and does not exit the gas generator exhaust.

[0074] A fire suppression system is also disclosed herein comprising: the gas generator described herein; and a storage tank for storing a fire suppression material; wherein the exhaust of the gas generator is arranged within the storage tank.

[0075] Arranging the exhaust of the gas generator inside the storage tank may enable the fire suppression material in the storage tank to act as a cooling agent for cooling the hot gases exiting the exhaust of the gas generator. As such, thermal mixing may be achieved and also the hot exhaust of the gas generator may be hidden away within the storage tank, thus minimising thermal hazards typically associated with gas generators.

[0076] This arrangement also enables the ratio of the quantity of gas generated by the gas generator to the quantity of fire suppression material initially stored in the storage tank to be selected during design of the system such that the mixture has the desired temperature when discharged. In embodiments where the gas generated by the gas generator is different to the fire suppression material stored in the storage tank, this arrangement also enables the composition of the fire suppressant discharged from the overall system to be altered or selected by altering or selecting the ratio of the proportion of fire suppressant released from the gas generator to the proportion of fire suppressant initially stored in the storage tank.

[0077] Embodiments also enable the size of the system to be relatively low. For a given amount of fire suppressant to be discharged from the overall system, the combination of the storage tank and gas generator enables a smaller and lighter system than gas tanks alone.

[0078] Although the present invention has been described with reference to 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 invention as set forth in the accompanying claims.