AU2017203659B1 - Fire extinguishing composition and apparatus - Google Patents

Abstract

The present invention relates to fire extinguishing compositions and methods of using such compositions to extinguish fires. The invention also relates to apparatus for applying the fire extinguishing compositions. In particular, the invention relates to fire extinguishing compositions that can be used on a range of fire types.

Description

ι 2017203659 31 May 2017

FIRE EXTINGUISHING COMPOSITION AND APPARATUS TECHNICAL FIELD

[0001] The present invention relates to fire extinguishing compositions and methods of using such compositions to extinguish fires. The invention also relates to apparatus for applying the fire extinguishing compositions. In particular, the invention relates to fire extinguishing compositions that can be used on a range of fire types.

BACKGROUND ART

[0002] Existing fire extinguishers rely on the action of certain materials on a fire, either to reduce the heat content of the combustibles to a point where combustion is not sustainable, or to deprive the fire of an essential component, such as oxygen.

[0003] Fire extinguishers are divided into various types which are limited in their application for either environmental or safety reasons. For example, water extinguishers are not safe to use on a fire in an area which has live electricity.

[0004] Fires are generally classified into one of six classes: • Class A - fires which involve ordinary combustible materials, such as cloth, paper, rubber and wood • Class B - fires which involve flammable or combustible liquids such as petroleum products, greases and oils • Class C - fires which involve combustible gases such as liquefied petroleum gas (LPG), butane and acetylene • Class D - fires which involve combustible metals such as sodium, magnesium and aluminium • Class E - fires which involve motors, switches or other electrical equipment where live electrical currents are flowing • Class F - fires which involve cooking oils and fats.

[0005] Furthermore, most convention fire extinguishers are classified according to the component(s) of the extinguishing agent: (i) water 2 (ii) foam 2017203659 31 May 2017 (iii) powder (iv) carbon dioxide (v) vaporizing liquid (vi) wet chemical [0006] Each type of extinguishing agent is used for extinguishing fires with a particular fuel, that is, for a fire of a particular class. For example, water extinguishers are only suitable for Class A fires, whereas foam extinguishers are suitable for Class A and Class B fires. With regards foam extinguishers when used on a Class B fire, some act by depositing a film between the flammable liquid and the fire.

[0007] A limitation of some foams that are used for Class A fires, is the residue that remains. For example, Class A foams that are approved for use in Victoria, Australia, must be at least 60 % biodegradable within 28 days. However, such foams cannot be used on properties that are labelled as organic, or certified organic, otherwise those properties are at risk of losing their label or certification. Furthermore, even on non-certified properties, it is recommended to allow at least one rainfall to wash away residue before any pasture exposed to Class A foam is used for grazing stock. Feed that has been tainted and/or contaminated by Class A foam cannot be used, a water body used for domestic supply, such as a damn or water storage tank that has been exposed to Class A foam should be flushed with fresh water before re-using, and there may be a withholding period for any affected stock. Given the high propensity for bushfires throughout rural regions of countries, such as Australia, which spread through grazing and farm lands, an alternative to Class A foam that is non-toxic, environmentally friendly or rapidly biodegradable would be advantageous.

[0008] Liquefied gas extinguishers can be used on Class B and Class E fires. There are two general types of liquefied gas extinguishers, non-halon and carbon dioxide (CO2). Previously, this group of extinguishers included halon, however, due to the ozone-depleting nature of halon, it is no longer used in extinguishers in some countries, including Australia.

[0009] Whilst halons were very effective as a fire extinguishing agent, there were limitations. Due to the complex chemical reaction which occurs during extinguishing, the halons operated best in either a closed space, where there is a contained oxygen supply, or in very close proximity to the fire. They were not as effective in outdoor use where the oxygen supply surrounding the fire is abundant, particularly when sprayed from large distances toward a fire. 3 2017203659 31 May 2017

Therefore, they were not particularly effective in extinguishing fires when sprayed at a distance from the flames.

[0010] Another limitation was the heat remaining after extinguishing of a fire using halons. Consequently, halons did not prevent re-ignition of a fire. Research has been undertaken to find a replacement for halons, however, nothing to date is as effective whilst being harmless to the environment.

[0011] Dry chemical (also known as dry powder) extinguishers can also be used on Class B and Class E fires. There are also some dry powder extinguishers that can be used on Class A fires. Dry powder extinguishers are therefore advantageous in that they can be used on a number of different types of fires. They also act rapidly to extinguish a fire, are compact and can cover a large area. However, there are disadvantages associated with the use of such extinguishers. In particular, the extensive spread of powder that has to be cleaned up after a fire has been extinguished. If the dry powder extinguisher has been used within a building, the powder can damage equipment, such as computers, and there is also the risk of respiratory problems as a result of powder and dust remaining even after clean up. Furthermore, as dry powder extinguishers lose pressure quickly after activation, they are better suited for small, indoor fires, and therefore the disadvantages mentioned are a very real consideration.

SUMMARY OF INVENTION

[0012] The present invention is directed to a fire extinguishing composition with the ease and convenience of current extinguishers for Class A fires, but that can also be used for other classes of fire, such as Class B, Class C or Class F fires. The fire extinguishing composition may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

[0013] With the foregoing in view, the present invention in one form, resides broadly in a fire extinguisher material comprising sodium sulphite and sodium bicarbonate.

[0014] The fire extinguisher material is preferably provided as a solid. Any suitable material known in the art can be used in the preparation of the fire extinguisher material as a solid. For example, compounds that are commonly used as an excipient to act as a binder in tablet formulation can be used in the preparation of the fire extinguisher material as a solid. Thus, sugars (including sucrose and liquid glucose), natural binders (including alginic acid, starch paste, gelatin and cellulose) and synthetic or semisynthetic polymers (including hydroxyl propyl methyl cellulose (HPMC), polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG)) can be 4 used as the binder in a solid fire extinguisher material according to the present invention. 2017203659 31 May 2017 [0015] Preferably, the binder is water soluble. A water soluble binder enables a fire extinguisher material comprising sodium sulphite, sodium bicarbonate and the binder to be readily dispersed using water, and therefore readily dispersed to extinguish a fire.

[0016] Even further preferred, is for the binder to be a solid at room temperature. As used herein, the phrase ‘room temperature’ is intended to be a temperature within the range of about 15 °C to about 25 °C. Using a binder that is a solid at room temperature enables a fire extinguisher material comprising sodium sulphite, sodium bicarbonate and the binder to be easily transported, without requiring transport precautions, such as those required to avoid spillage, that might be necessary for liquid transportation.

[0017] In some embodiments of the invention, the sodium sulphite and sodium bicarbonate can be combined with a high molecular weight polyethylene glycol to form a solid. In a particularly preferred embodiment, the high molecular weight polyethylene glycol is polyethylene glycol 1500 (PEG-1500). The fire extinguisher material is thus a solid comprising sodium sulphite, sodium bicarbonate and PEG-1500.

[0018] In fire extinguishing material according to the invention, the sodium sulphite is preferably provided at a concentration between 0.05 M and 0.20 M, and the sodium bicarbonate is preferably provided at a concentration between 0.10 M and 0.50 M.

[0019] Typically, the sodium sulphite and sodium bicarbonate will be provided in a weight (w) ratio. Fire extinguisher material according to the invention can comprise any suitable weight ratio of sodium sulphite to sodium bicarbonate. Preferably, the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.1:1 to 5:1. Even more preferably, the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.1:1 to 3.5:1. A particularly preferred weight ratio of sodium sulphite to sodium bicarbonate is 0.2:1 to 0.4:1. The weight ratio of sodium sulphite to sodium bicarbonate in a fire extinguishing material of the invention can thus be 0.2:1, 0.3:1, 0.4:1, or any value between.

[0020] Although not wishing to be bound by theory, or limited to a particular reaction mechanism or pathway, one possible reaction mechanism is as follows:

Dissociation of sodium bicarbonate in aqueous solution to form a serious of equilibrium reactions: (I)

NaHCOs + H20 <-> Na+ + HCOf + H20 ^ Na+ + H2C03 + OH' + C02 5 2017203659 31 May 2017

The CO2 will remain dissolved, but dependent on the partial pressure, will be in equilibrium with gaseous CO2.

Heating the solution vigorously (as in a fire situation) will drive the equilibrium to the right, generating CO2 gas. Heating can also produce sodium carbonate that will decompose in fire according to the following equations: 2 NaHC03 Na2C03 (s) + H20 + CO (g) (II)

Na2C03 (s) -* Na20 (s) + C02 (g) (III)

Reaction (II) takes place at around 200 °C, and reaction (III) takes place at around 850 °C. Furthermore, when sodium sulphite is added to water, it will react with any dissolved oxygen, thereby depleting its availability to any combustion reactions as follows: 2 Na2S03 + 02 -η- 2 Na2S04 (IV) [0021] In the above reaction mechanism, the sodium sulphite acts as an oxygen scavenger and the sodium bicarbonate is broken down to produce carbon dioxide. The overall effect is to deprive the fire of oxygen whilst simultaneously producing carbon dioxide to douse the fire.

[0022] As can be seen from the above reaction mechanism, the end products of the reaction when the fire extinguishing material is used to put out a fire are non-toxic or readily biodegradable.

[0023] In a further form, the present invention residues in a dispensing system for applying a fire extinguishing material comprising sodium sulphite and sodium bicarbonate to a fire. Preferably, the dispensing system can be retro-fitted to current fire fighting equipment utilised for water. For example, the dispensing system can be retro-fitted to fire engines, landing valves or sprinkler systems.

[0024] The dispensing system comprises a container for the fire extinguishing material. Preferably, the container is enclosed, so that the fire extinguishing material is not exposed to moisture in the air, prior to use.

[0025] In a preferred embodiment, the container has a fluid inlet through which water can pass into the container, and mix with the fire extinguishing material within the container to provide a fire extinguisher solution. The container can also have a fluid outlet through which the fire extinguisher solution can egress from the container. In some embodiments, the fluid inlet and fluid outlet can be the same. In such embodiments, a measured amount of water passes 2017203659 04 Μ 2017 6 through the fluid inlet into the container, mixes with the fire extinguishing material and the fire extinguisher solution then egresses the container through the inlet. The amount of fire extinguisher solution that can be produced at any one time is thus limited by the volume of the container.

[0026] In alternative embodiments, the fluid inlet and the fluid outlet are separate. In these embodiments, water can pass into the container through the fluid inlet as a continuous flow, whilst the fire extinguisher solution simultaneously egresses the container via the fluid outlet, thus providing for a continuous flow of fire extinguisher solution.

[0027] Preferably, each fluid inlet and fluid outlet comprises a valve, so that passage of water therethrough can be regulated.

[0028] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0029] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

[0029a] Definitions of the specific embodiments of the invention as claimed herein follow.

[0029b] According to a first embodiment of the invention, there is provided a fire extinguisher material comprising sodium sulphite and sodium bicarbonate, wherein the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.2:1 to 0.4:1 (w/w).

[0029c] According to a second embodiment of the invention, there is provided a method of preparing a fire extinguisher material comprising the following steps: (i) combining sodium sulphite and sodium bicarbonate in a weight ratio between 0.2:1 to 0.4:1 (w/w); (ii) optionally adding a water soluble binder ; and (iii) mixing to form a homogenous material. 2017203659 04 Μ 2017 6a [0029d] According to a third embodiment of the invention, there is provided a method of extinguishing a fire comprising regulating a flow of water through a fire extinguisher material comprising sodium sulphite and sodium bicarbonate, wherein the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.2:1 to 0.4:1 (w/w), such that as the water comes into contact with the fire extinguisher material, it dissolves the fire extinguisher material, resulting in a fire extinguishing solution.

BRIEF DESCRIPTION OF DRAWINGS

[0030] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: [0031 ] Figure 1 is a schematic of a manual dispensing system according to one embodiment of the present invention; and [0032] Figure 2 is a schematic of an automatic dispensing system according to another embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

In accordance with the present invention, the fire extinguisher material is a mixture of sodium sulphite and sodium bicarbonate. The inventor has found that when mixing the components in certain weight ratios, the production of C02 in situ was in amounts which were [Text continues on page 7.] 7 2017203659 31 May 2017 useful in extinguishing fires. It was also found that the mixture was valuable in the extinguishing not only of Class A fires, but the mixture could also be used to treat fires of Class B, Class C and Class F. The components used in the fire extinguisher material are relatively inexpensive and therefore provide a material that is capable of successfully extinguishing a number of fire types, without significantly increasing the cost of extinguishing material.

[0034] The fire extinguisher material can be used with a conventional water fire extinguisher cylinder. Preferably, the fire extinguisher material is used in a dispensing system that can be retro-fitted as a component of known fire fighting systems that utilise water. For example, the fire extinguisher material can be used in a dispensing system incorporated into a system associated with a fire engine, landing valve or sprinkler system.

[0035] Turning to Figure 1, there is shown a schematic of a manual dispensing system 10 according to one embodiment of the present invention. The manual dispensing system 10 is retro-fitted to a fire hose on a fire engine or a fire hydrant valve using camlock joints 12, 12’.

The camlock joints 12, 12’ are associated with ball valves (not separately indicated) through which the flow of water can be regulated. The manual dispensing system 10 comprises a container 14 in which the solid fire extinguisher material is stored. The container 14 has a water inlet ball valve 16 and a water outlet 18 associated with a Venturi injector 20.

[0036] In use, water flows through the fire hose, and some water is diverted via the ball valve associated with camlock joint 12 to the water inlet ball valve 16 and into the container 14. The water dissolves the solid fire extinguisher material in the container 14, and the resultant solution exits the container 14 via the outlet 18 and returns to the fire hose via the Venturi injector 20, where it can be dispensed from the fire hose using a fire nozzle 22. The dispensing system 10 is manual as it requires the ball valve associated with camlock joint 12 to be manually opened to allow flow of water through the retro-fitted dispensing system 10.

[0037] In Figure 2, there is shown a schematic of an automatic dispensing system 30 according to another embodiment of the present invention. The automatic dispensing system 30 is retro-fitted to a sprinkler system using camlock joints 32, 32’. The camlock joints 32, 32’ are associated with ball valves (not separately indicated) through which the flow of water can be regulated. The automatic dispensing system 30 comprises a container 34 in which the solid fire extinguisher material is stored. The container 34 has a water inlet solenoid valve 36 and a water outlet 38 associated with a Venturi injector 40.

[0038] In the event of a fire, a glass bulb in the sprinkler head 42 bursts and releases 8 2017203659 31 May 2017 pressurised water in the sprinkler pipe line. The release of the pressurised water results in a drop in pressure in the system which is sensed by a pressure differential switch or flow switch 44 (not separately indicated) which will then set off an alarm in an associated control panel (not indicated). The water inlet solenoid valve 36 is then actuated, allowing some water from the sprinkler pipeline to be diverted via the ball valve associated with camlock joint 32 into the container 34. The water dissolves the solid fire extinguisher material in the container 34, and the resultant solution exits the container 34 via the outlet 38 and returns to the sprinkler pipeline via the Venturi injector 40, where it is dispensed from the sprinkler head 42. The dispensing system 30 is automatic as it relies on the combination of the pressure differential switch or flow switch 44 and the water inlet solenoid valve 36 to automatically allow flow of water through the retrofitted dispensing system 30.

EXAMPLES

Example 1 [0039] Sodium sulphite (1,000 g; 7.9 M) was combined with sodium bicarbonate (3,000 g; 35.7 M) to provide a mixture with a weight ratio of sodium sulphite to sodium bicarbonate of 1:3.0 (w:w).

[0040] Polyethylene glycol 1500 (500 g) was melted in a jacketed, temperature controlled heating kettle set at 60 °C and fitted with a spiral mixing arm. Once the PEG1500 had melted, the spiral arm was turned on and the mixture of sodium sulphite and sodium bicarbonate was added to the kettle and mixing continued until the combined mixture was fully mixed.

[0041 ] The combined mixture of PEG 1500, sodium sulphite and sodium bicarbonate was then transferred from the heating kettle to a canister and allowed to set at room temperature.

Example 2 [0042] A comparison of the effectiveness of a fire extinguisher material according to the present invention and water was undertaken. Under controlled conditions, a Class B fire was lit on a 3.0 m x 3.0 m metal pan filled with a 50:50 (volume:volume) mixture of petrol and diesel (40 L). Using a standard water extinguisher, it took 35 seconds to completely extinguish the fire. However, the force of the water from the extinguisher acted to wash/push the petrol and diesel from the pan, so that the remaining flammable mixture was more rapidly extinguished. Relying solely on water to extinguish such a fire would therefore in reality, take well in excess of 35 seconds. 2017203659 31 May 2017 9 [0043] Using an extinguisher retrofitted with a dispensing system utilising the fire extinguishing material as described in Example 1, it took 17 seconds to completely extinguish the fire. In contrast to using the standard water extinguisher, the retrofitted extinguisher did not push any petrol and diesel from the pan, therefore the 17 seconds to extinguish the fire is a true indicator of the extinguishing ability of the material of the present invention. Specifically, as the material comes into contact with a fire, it deprives the fire of oxygen and the generated carbon dioxide quickly douses the fire.

[0044] It can therefore be seen that the invention provides fire extinguisher compositions that are relatively inexpensive, can be used on a variety of fires, and are non-toxic.

[0045] In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0046] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0047] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (20)

1. A fire extinguisher material comprising sodium sulphite and sodium bicarbonate, wherein the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.2:1 to 0.4:1 (w/w).

2. The fire extinguisher material of claim 1, further comprising a binder.

3. The fire extinguisher material of claim 2, wherein the binder is water soluble.

4. The fire extinguisher material of claim 3, wherein the binder is solid at room temperature.

5. The fire extinguisher material of claim 4, wherein the binder is selected from the group consisting of sugars, alginic acid, starch paste, gelatin, cellulose, synthetic polymers and semisynthetic polymers.

6. The fire extinguisher material of claim 5, wherein the binder is polyethylene glycol 1500 (PEG-1500).

7. The fire extinguisher material of any one of claims 1-6, wherein the concentration of sodium sulphite is between 0.05 M and 0.20 M.

8. The fire extinguisher material of any one of claims 1-7, wherein the concentration of sodium bicarbonate is between 0.10 M and 0.50 M.

9. The fire extinguisher material of claim 6, wherein the weight ratio of PEG-1500 to sodium sulphite to sodium bicarbonate is 1:2:6.

10. A method of preparing a fire extinguisher material comprising the following steps: (i) combining sodium sulphite and sodium bicarbonate in a weight ratio between 0.2:1 to 0.4:1 (w/w); (ii) optionally adding a water soluble binder ; and (iii) mixing to form a homogenous material.

11. The method of claim 10, wherein the water soluble binder is selected from the group consisting of sugars, alginic acid, starch paste, gelatin, cellulose, synthetic polymers and semisynthetic polymers.

12. The method of claim 11, wherein the binder is PEG-1500.

13. The method of claim 12, wherein step (ii) comprises adding PEG-1500 that has been heated to about 60 °C.

14. The method of claim 13, further comprising the following step: (iv) cooling the homogenous mixture of sodium sulphite, sodium bicarbonate and PEG-1500 to room temperature to form a solid fire extinguisher material.

15. A method of extinguishing a fire comprising regulating a flow of water through a fire extinguisher material comprising sodium sulphite and sodium bicarbonate, wherein the weight ratio of sodium sulphite to sodium bicarbonate is within the range 0.2:1 to 0.4:1 (w/w), such that as the water comes into contact with the fire extinguisher material, it dissolves the fire extinguisher material, resulting in a fire extinguishing solution.

16. The method of claim 15, wherein the fire extinguisher material further comprises a water soluble binder.

17. The method of claim 16, wherein the water soluble binder is selected from the group consisting of sugars, alginic acid, starch paste, gelatin, cellulose, synthetic polymers and semisynthetic polymers.

18. The method of claim 17, wherein the water soluble binder is polyethylene glycol 1500 (PEG-1500).

19. The method of claim 18, wherein the weight ratio of PEG-1500 to sodium sulphite to sodium bicarbonate is 1:2:6.

20. The method of any one of claims 15-19, wherein the fire is selected from the group consisting of Class A, B, C and F fires.