GB2550004B - Fire extinguishing device - Google Patents

Description

FIRE EXTINGUISHING DEVICE

TECHNICAL FIELD OF THE INVENTION

The present .invention relates to a fire extinguishing device, and a method of manufacturing the fire extinguishing device.

BACKGROUND TO THE INVENTION

Chip-pan fires are a well-known hazard, which can occur in domestic or commercial kitchens when oil is heated to above a given temperature, which may vary depending on the type of oil. It has long been known that the worst thing to do in the event of a chip-pan fire is to pour water on it. Water is denser than oil, and sinks to the bottom where the boiling oil vaporizes it almost instantaneously. The rapid expansion in volume associated with, the vaporization causes the chip pan to explode. Rather, in the event of a chip-pan fire, the most prudent way of extinguishing it is to smother it with a damp (but not dripping wet) towel or fire blanket. In so doing, the fire is starved of oxygen and soon goes out. Alternative methods of dealing with chip-pan fires include sprinkling salt on it, which absorbs the heat from the grease to the point where it is no longer able to support a fire. Similarly, sprinkling baking soda on it can smother the fire by releasing carbon dioxide. However, there are two disadvantages associated with these methods: (i) a very large amount of salt/baking soda is required in order to put out anything other than a very small fire, and (ii) in order to pour sufficient baking soda/salt on the fire, it is necessary to get close to the fire, which increases the risk of injury. The present invention aims to address these problems.

SUMMARY OF THE INVENTION

Broadly speaking, the present invention provides a fire extinguishing device which, avoids the problems set out above by allowing a user to drop a single contained packet into a fire, which causes the fire to be swiftly and safely extinguished. In this way, the risk of injury to the user is significantly reduced. 1 in order to achieve this, a first aspect of the present invention provides a fire extinguishing device as set out. in claim 1.

The packet preferably defines a pouch in which the fluid resides or which contains the fire extinguishing fluid, and the pouch preferably being watertight. The fire extinguishing fluid is preferably a liquid.

Optional features of the invention will now be set out. These are applicable singly or in any combination with any aspect of the invention.

In this way, the packet may be thrown onto or into a fire such as a chip-pan fire, causing the packet to rupture. Accordingly, the fire extinguishing device is preferably hand-held. By "hand-held", we mean that the device has dimensions and weight that enable it. to be held in the hand of a user. Upon rupture, the fire extinguishing fluid is released and spreads out over the fire, to extinguishing it. The rupture may be caused by melting of the material making up the packet. The smoke point of cooking oil (i.e. the temperature at which the oil begins to smoke) generally ranges from 200°C to 240“C, and the auto-ignition point of cooking oil (i.e. the temperature at which the oil ignites) is generally around 330°C to 380°C. In order to melt in these conditions, the packet (more specifically, material which makes up the packet) preferably has a melting point which, is lower than the auto-ignition point, i.e. no more than 380°C, and more preferably no more than 330°C. For particularly good safety, the material making up the packet preferably has a melting point lower than 3 00°C. The material from which the packet may be made will be discussed in detail later on in the application. In other embodiments, the rupture may be caused by burning, disintegration, or decomposition of the material making up the packet in response to the elevated temperature of the fire.

The packet preferably comprises plastic and in preferred embodiments, the packet is made entirely of plastic. Plastics from which the packet may be made include: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene (PE), polyethylene terephthalate (PET), polyester or nylon. The thickness of the packet, i.e. the thickness of one sheet of material which makes up the packet (rather than the thickness of the two opposing walls combined) may be no less than 200pm and no more than 400pm. Preferably, this thickness is no less than 250pm and no more than 350pm, and more preferably this thickness is no less than 280pm and no more than 320pm. In other embodiments, which are directed towards use in commercial kitchens, where there may be a higher volume of cooking oil, the packet may comprise acrylic, which may have a thickness no less than 1mm and no more than 3mm. More preferably, such a packet has a thickness of no less than 1.5mm and no more than 2mm. These packets are larger, and so require a greater thickness for improved support.

The material making up the packet may have a laminated structure or, in other words, the material making up the packet may include a plurality of layers. The plurality of layers may all be made from the same material or alternatively they may be made from a plurality of different materials. In one preferred embodiment, the material making up the packet may have a triple-laminated structure, having a first (i.e. inner) layer, a second (i.e. middle) layer and a third (i.e. outer) layer. The first layer may comprise LLDPE, the second layer may comprise PET and the third layer may include PET. In this embodiment, it was found that due to conduction of heat across the surface of the outer layer, rather than rupturing at a single hot spot in the flames, a larger area of the packet ruptured at once. This has two advantages: (i) firstly, it reduces the chance of a jet of fire extinguishing fluid emerging from a small rupture point, which could be both dangerous, and result in less fire extinguishing fluid spreading over the fire, and (ii) secondly, it means that a larger area of the fire may be covered with fire extinguishing liquid in a faster time, rather than having to spread out from the rupture point.

The packet may comprise two sheets of material which are sealed together around their edges, to ensure that the packet is watertight and prevent leakage. The central region in which the sheets are not sealed together forms the pouch in which the fire extinguishing fluid resides. The two sheets may be joined in a number of different ways, such as: adhesives such as glue, welding together. Similarly, the packet may be formed of a single sheet of material which is folded over, and sealed around the edges which do not form the fold. Such a packet may be sealed using the same methods as those comprising two sheets.

When extinguishing a fire, in order to avoid injury to the user, it is clearly preferable that they do not have to place their hand directly over or in the flames in order to place the fire extinguishing device into the fire. Accordingly, in preferred embodiments of the present invention, the packet has a generally elongated shape. For example, the packet may be rectangular or substantially rectangular in shape. An aspect ratio of the packet may be defined as the ratio of the length of the packet to the width of the packet (the length being perpendicular or substantially perpendicular to the width. For example, the aspect ratio may be two or greater, three or greater, four or greater, or five or greater. Preferably the aspect ratio is between four and five, inclusive. By having an elongated shape, as described, a user may hold the packet at one end when throwing it into the fire. Specifically, considering the example of a chip-pan fire or other kitchen fire, the user may hold the packet at one end of its length, while placing the opposite end on the rim of the pan. Then, the user is able to slide the packet over the rim into the fire without having to move too close to the flames. The specific dimensions of the fire extinguishing device will be discussed in greater depth later in the application.

The packet may be stiff. Specifically, the fire extinguishing device may have a stiffness sufficient to allow it not to sag when held at or near one end, e.g. as described in the previous paragraph. For example, it is preferred that when the packet is held near its end (e.g. at a point between 10% and 20% of the length of the packet from one end of the packet), so that the portion which is being held is horizontal, that the other end is deflected vertically by no more than 50% of the length of the packet, and more preferably no more than 20% of its length, and more preferably still no more than 10% of its length (this is illustrated more clearly in Fig. 3). Furthermore, it is also preferable that when held in such a location, the packet does not buckle or fold, since this could cause the packet to hit a burning liquid at speed and cause splashing and risk of injury. In some embodiments, when the packet is held horizontally at the end as described above, the product may bend no more than 30°, more preferably no more than 20° and most preferably no more than 10°. This may be achieved in a number of ways. For example, in some embodiments, the material of the packet itself may have the requisite stiffness. While the material making up the packet may be uniform, or substantially uniform, the stiffness may be achieved by having a thicker portion of material on one side, or both sides.

To provide the requisite stiffness, the packet contains a stiffening member in addition to the fire extinguishing fluid, the stiffening member may be located in the pouch. When the packet is held at the ’'end", as described above, both the stiffening member and the packet are held.

The stiffening member has a higher stiffness than the packet itself, and may be made from e.g. PVC or acrylic. The stiffening member is preferably not attached or sealed to the internal walls of the pouch. By having a separate stiffening member, it is possible for the material making up the packet to be thinner, allowing it to rupture more quickly on contact with fire. However, when the packet is made up of a plurality of layers, as discussed above, the stiffening member may be incorporated between two of these layers. In some embodiments, the stiffening member may be no less than 0.5mm thick and no less than 1.5mm thick, more preferably no less than 0,75mm thick and no more than 1,25mm thick. Most preferably, the stiffening member is no less than 0.9mm thick, and no more than 1mm thick. Data sheets setting out some additional properties of the stiffening member may be found in Annex A.

In related examples in which, the stiffening member is a separate feature 5 from the packet itself, it preferably has similar dimensions to those of the pouch containing the fire extinguishing fluid.

Specifically, the stiffening member preferably has the same or substantially the same length as the pouch. For example, the length of the stiffening member may differ by no more than 20% from the length of the pouch, and more preferably the length of the stiffening member may differ by no more than 10% from the length of the pouch. Accordingly, like the packet itself, the stiffening member preferably has a generally elongated shape, e.g. rectangular or substantially rectangular. For example, the stiffening member may be in the form of a rectangular sheet of material (the materials discussed above). Using the same definition as above, the aspect ratio of the stiffening member may be five or greater, six or greater, seven or greater, but is preferably eight or greater. In preferred embodiments, the aspect ratio is between eight and ten inclusive. In alternative embodiments, the stiffening member may be in the form of a rod, rather than a sheet. The stiffening member preferably has rounded edges, or in other words: no sharp edges, in order to prevent piercing of the material making up the packet which would clearly cause leakage of the fire extinguishing fluid. For example, in embodiments in which, the stiffening member is in the form of a sheet of material, the corners of the sheet may be rounded, and in embodiments in which the stiffening member is in the form of a rod, each end of the rod may be rounded off.

The dimensions of the packet are preferably selected based on the intended use of the fire extinguishing device. Specifically, the dimensions of the packet are preferably selected based on the volume of fire extinguishing fluid to be contained therein. For example, in fire extinguishing devices to be used to put out fires in domestic pans, such as frying pans and saucepans, the packet preferably contains between 50ml and 100ml of fire extinguishing fluid, more preferably the packet contains between 70ml and 90ml of fluid, more preferably still the packet contains between 75ml and 85ml of fluid. In an exemplary embodiment, the packet may contain 80ml of fire extinguishing fluid. It has been found that volumes falling within the ranges set out in the preceding sentences are sufficient to put out up to 2 litres of burning oil, without there being so much fire extinguishing fluid that there is overspill of the fire extinguishing fluid. Similarly, in commercial kitchens, where larger volumes of oil may be used, a larger volume of fire extinguishing fluid is required. For example, the packet may contain between 150ml and 300ml of fire extinguishing fluid, or more preferably between 220ml and 280ml of fluid, and more preferably still the packet may contain between 230ml and 250ml of fluid. Such volumes have been found to be effective at putting out up to 20 litres of burning oil.

The fire extinguishing fluid preferably contains potassium carbonate, K2CO3. When exposed to the cooking oil fire, the potassium carbonate causes saponification of the fat converting it into non-combustible soap. This process is endothermic, so also absorbs thermal energy from the surroundings, so decreasing their temperature. Furthermore, when potassium carbonate is exposed to high temperatures, it decomposes to release carbon dioxide, which has a suffocating effect on the fire. The fire extinguishing fluid preferably also contains water, which of course releases steam at high temperatures, also having a suffocating effect on the flames.

In addition to this the combination of carbon dioxide and steam with the saponified fat (a soapy substance) creates a foam which both reduces access to oxygen and covers the burning surface of the oil.

It will be understood that, unless otherwise specified, all percentages of components of the fluid expressed herein are by weight, relative to the total weight of the fluid.

In some embodiments, the fire extinguishing fluid comprises at least 30 wt% potassium carbonate, for example at least 31 wt%, at least 32 wt%, at least 33 wt%, at least 34 wt%, at least 35 wt%, at least 36 wt%, at least 37 wt%, at least 38 wt%, at least 39 wt% or at least 40 wt%.

In some embodiments, the fire extinguishing fluid comprises up to 60 wt% potassium carbonate, for example up to 59 wt%, up to 58 wt%, up to 57 wt%, up to 56 wt%, up to 55 wt%, up to 54 wt%, up to 53 wt%, up to 52 wt%, up to 51 wt% or up to 50 wt%.

In some embodiments there may be 30 to 60 wt% potassium carbonate, the percentages being relative to the total weight of the fluid. In some embodiments there may be 35 to 55 wt% potassium carbonate, for example 40 to 50 wt%.

The fluid may also include 0 to 5 wt% of surfactant, for example 0 to 4.5 wt%, 0 to 4 wt%, 0 to 3.5 wt%, 0 to 3 wt%, 0 to 2.5 wt% or 0 to 2 wt%. In some embodiments, the fluid does not contain any surfactant. In some embodiments, the fluid comprises at least 0.5 wt% surfactant, for example at least 0.6 wt%, at least 0.7 wt%, at least 0.8 wt%, at least 0.9 wt%, at least 1 wt%, at least 1.5 wt%, at least 2 wt% or at least 2.5 wt%. In some embodiments, the fluid comprises up to 10 wt% surfactant, for example up to 9.5 wt%, up to 9 wt%, up to 8.5 wt%, up to 8 wt%, up to 7.5 wt%, up to 7 wt%, up to 6.5 wt%, up to 6 wt% or up to 5.5 wt%.

In some embodiments, the fluid comprises up to 5 wt% surfactant, for example up to 4.9 wt%, up to 4.8 wt%, up to 4.7 wt%, up to 4.6 wt%, up to 4.5 wt%, up to 4 wt%, up to 3.5 wt% or up to 3 wt%.

In some embodiments, the surfactant comprises a single type of surfactant. In other embodiments, the surfactant comprises two or more different types of surfactant, for example two, three, four, five or six different types of surfactant.

In some embodiments, the surfactant is selected from one or more of anionic, cationic, non-ionic and amphoteric surfactants. In some embodiments, the surfactant is a fluorocarbon and/or hydrocarbon surfactant. FOMTEC AFFF 1%, 3% or 6% may be used. In the following description, "FOMTEC AFFF 1%", "FOMTEC AFFF 3%", and "FOMTEC AFFF 6%" refer to commercially available surfactant solutions which have been shown to be effective.

The remainder of the fluid is preferably water, and more preferably demineralized water. It will be understood that the fire extinguishing fluid may contain small amounts of impurities which are inevitably present in the water and other components.

In some embodiments, the fire extinguishing liquid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt%; 0 to 10 wt% surfactant, for example 0 to 5 wt%; and balance water.

In some embodiments, the fire extinguishing liquid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt%; and balance water.

In some embodiments, the fire extinguishing liquid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt%; 0.5 to 10 wt% surfactant, for example 0.5 to 5 wt%; balance water.

In some embodiments, the fire extinguishing liquid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt%; 0 to 10 wt% FOMTEC AFFF (either 1%, 3% or 6%), for example 0 to 5 wt%; and balance water.

In some embodiments, the fire extinguishing liquid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt%; 0.5 to 10 wt% FOMTEC AFFF (either 1%, 3% or 6%), for example 0.5 to 5 wt%; balance water.

For example, in some embodiments, the fluid may contain 4 0 wt% potassium carbonate and 60 wt% water. In other embodiments the fluid may contain 50 wt% potassium carbonate and 50 wt% water. in other embodiments, the fluid may contain 50 wt% potassium carbonate, 45 wt% water and 5 wt% surfactant. A second aspect of the present invention provides a method for manufacturing a fire extinguishing device according to the first aspect of the invention, as set out in claim 22.

Further optional features of the invention are set out below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 shows a perspective view of a fire extinguishing device.

Fig. 2 shows an alternative perspective view of a fire extinguishing device .

Fig. 3 shows schematically the stiffness properties of the fire extinguishing device.

DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a perspective view of a fire extinguishing device according to the first aspect of the present invention.

Specifically, the drawing shows a packet 10, which in this case is a rectangular packet having two long edges 12a, 12b, each having length 255mm and two short edges 14a, 14b having length 60mm. The packet 10 is formed by welding together two sheets of material (e.g. a laminate of 120pm thick LLDPE, a layer of 12pm thick PET optionally having a design printed on it, and an outer layer of 12pm thick PET to protect the printed design) around each of the edges 12a, 12b, 14a, 14b. The sheets are welded together in welded regions 16a, 16b along the long edges 12a, 12b, and welded regions 18a, 18b along the short edges 14a, 14b. The welded regions 16a, 16b, 18b have approximately the same width iVweid, which in the embodiment shown in the drawing is approximately 7mm. Welded region 18a is thicker, with a width W' weid which is approximately 22mm. Welded region 18a includes a hole 22.

In the centre of the packet 10 is pouch 20, which contains the fire extinguishing fluid (not shown). The embodiment shown in the drawing is intended for domestic use, and accordingly contains 80ml of fluid, which as discussed previously, is sufficient to extinguish 2 litres of burning oil. The pouch 20 is sealed in a watertight manner on all four sides by the welded regions 16a, 16b, 18a, 18b.

Fig. 2 shows a perspective view of the same packet 10 this time emptied of fire extinguishing fluid, with a portion of the pouch 20 cut away, to show the stiffening member 24 inside. In this embodiment, the stiffening member 24 is in the form of a rectangular piece of e.g. PVC having length approximately 210mm and width approximately 25mm. The stiffening member 24 has rounded corners 26 at the end 28 to ensure that it does not pierce the material making up the packet 10. It should be noted that the corners at the other end (not shown) are also rounded for the same reason.

Fig. 3 illustrates schematically the stiffness properties of the packet 10 as described in the "Summary of the Invention" section.

In this drawing, the packet 10 is represented simply as a uniform rod having length 1 of uniform cross-section. As shown in Fig. 3, the packet 10 is supported at a point which is 0.152 from the far end (i.e. 15% from the end) by a force FSr and is deflected from the horizontal at the far end by a distance h. As described earlier in the application, it is preferable that when the packet is supported in a horizontal direction at a point which is 10% to 20% from one end, that the deflection is less than 50% of the length, 20% of the length or 10% of the length. In terms of Fig. 3, this may be expressed as: h L 1/2, 1/5 or 1/10.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the invention.

Claims (21)

1. A fire extinguishing device comprising: a packet defining a pouch containing a fire extinguishing fluid, the packet configured to rupture on contact with fire, to release the fire extinguishing fluid; and a stiffening member located inside the pouch, the stiffening member having a higher stiffness than the packet.

2. The fire extinguishing device of claim 1, wherein the pouch is water-tight.

3. The fire extinguishing device of any one of claim 1 or claim 2, wherein the packet has dimensions and mass which enable it to be held in the hand of a user.

4. The fire extinguishing device of any one of claims 1 to 3, wherein the stiffening member is not attached or sealed to the internal walls of the packet.

5. The fire extinguishing device of any one of claims 1 to 4, wherein the stiffening member has rounded edges.

6. The fire extinguishing device of any one of claims 1 to 5, wherein when the packet is supported horizontally at a point which is between 10% and 20% of the length of the packet from one end, the opposite end is deflected vertically by no more than 50% of the length of the packet.

7. The fire extinguishing device on any one of claims 1 to 6, wherein the packet comprises a material having a melting point of no more than 300°C.

8. The fire extinguishing device of any one of claims 1 to 7, wherein the packet comprises a plastic.

9. The fire extinguishing device of claim 8, wherein the packet comprises one or more of: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene (PE), polyethylene terephthalate (PET), polyester or nylon.

10. The fire extinguishing device of any one of claims 1 to 9, wherein the packet comprises two sheets of material sealed together at their edges.

11. The fire extinguishing device of claim 10, wherein the edges are sealed by welding.

12. The fire extinguishing device of any one of claims 1 to 11, wherein the packet has a generally elongated shape.

13. The fire extinguishing device of claim 12, wherein the packet is rectangular or substantially rectangular.

14. The fire extinguishing device of claim 12 or claim 13, wherein the packet has an aspect ratio of between four and five, inclusive.

15. The fire extinguishing device of any one of claims 1 to 14, wherein the stiffening member has a generally elongated shape .

16. The fire extinguishing device of claim 15, wherein the stiffening member is rectangular or substantially rectangular

17. The fire extinguishing device of claim 16, wherein the length of the stiffening member differs by no more than 20% from the length of the pouch.

18. The fire extinguishing device of any one of claims 1 to 17, wherein the packet contains between 50ml and 100ml of fire extinguishing fluid, inclusive.

19. The fire extinguishing device of any one of claims 1 to 18, wherein the packet contains between 150ml and 300ml of fire extinguishing fluid, inclusive.

20. The fire extinguishing device of any one of claims 1 to 19, wherein the fire extinguishing fluid comprises: 30 to 60 wt% potassium carbonate, for example 35 to 55 wt% ; 0 to 10 wt% surfactant, for example 0 to 5 wt%; and balance water.

21. A method of manufacturing a fire extinguishing device of any one of claims 1 to 20, the method including the steps of sealing together two sheets of material at their edges, leaving a gap in the perimeter where the two sheets are not sealed, filling a pouch through said gap with fire extinguishing fluid, locating a stiffening member inside the pouch, and sealing the gap to contain the stiffening member and the fluid.