GB2497820A

GB2497820A - Fire extinguishing composition and delivery apparatus

Info

Publication number: GB2497820A
Application number: GB201203123A
Authority: GB
Inventors: Yoshiyuki Katsuraku; John Grainger
Original assignee: WCM PRODUCTS Ltd
Current assignee: WCM PRODUCTS Ltd
Priority date: 2012-02-23
Filing date: 2012-02-23
Publication date: 2013-06-26
Anticipated expiration: 2032-02-23
Also published as: GB2497820B; WO2013124638A3; GB201203123D0; WO2013124638A2

Abstract

A fire extinguishing composition is disclosed comprising urea and a potassium containing compound selected from potassium carbonate, potassium bicarbonate, and mixtures thereof in a liquid carrier. The composition also preferably comprises one or more components selected from the following group: detergents, fire retardant materials, saponifying chemicals, antifreeze. A method of delivering fire extinguishing compositions is also disclosed, including a fire-extinguishing article comprising a fire-extinguishing composition housed in a container comprised at least in part of a material capable of melting or decomposing at or below the temperature of a cooking oil fire.

Description

Fire-extinguishing Compositions and Apparatus This invention relates to fire-extinguishing compositions, apparatus, and methods.

Fire-extinguishing compositions and apparatus are rated according to the type of fire for which they can be used.

In the following reference will be made to the UK classification, while recognising that different countries have different classifications. The invention is not limited to any particular classification and the use of 2 classification is intended as a convenient notation for describing types of fire.

In the United Kingdom the general classification is:-CLASS A: Solid state fires invoh'ing free burning materials [for example paper, wood, fabrics and other textiles and plastics.] CLASS B: Flammable solids and liquids [for example diesel, petrol and oils (not cooking] and solid fuels such as wax].

CLASS C: Flammable gas fires [for example propane, butane and methane].

CLASS D: Flammable metal fires [for example sodium, potassium and magnesium].

CLASS F: Cooking oil and fat fires.

Electrical tires such as switchgear and computers have no direct class (but are sometimes referred to as class E]. For such fires the procedure is to find source of electric power and switch it off, then tackle fire accordingly.

Different fire-extinguishing compositions are required for different types of fire.

Compositions for extinguishing cooking oil tires (Class F) have particularly difficult requirements to meet It has long been recognised that once cooking oils or fats ignite, the composition changes lowering the ignition temperature so that the fire becomes self-sustaining.

For such fires wet chemical fire extinguishers are used that use potassium salts [typically potassium acetate, although potassium citrate and potassium carbonate may also be used] which provides a saponifying effect, reacting with fatty acids in the cooking oil to form a layer of foam over the surface which smothers the fire and cools the surface of the fat. This saponifying effect only works on animal fats and vegetable oils and so typically a Class F extinguisher cannot normally be used for Class B fires.

Such wet chemical compositions are generally supplied in fire extinguishers for spraying the chemical onto the surface of the fire. A problem with spraying is that while it provides rapid access of fire-extinguishing compositions to the source of the fire, the extinguishers are bulky in comparison with the amount of fire-extinguishing composition provided. Additionally, the use of such extinguishers especially in a domestic environment, requires someone to remain close to the fire using the extinguisher, potentially exposing them to hazard.

It is known to use dry potassium bicarbonate on Class B and C fires. It is also known to use powder fire extinguishers comprising a potassium bicarbonate/urea complex for Class B and C fires. This material is used in preference to other potassium containing powders because of its ability to decrepitate [break up into smaller particles] giving a large surface area for free radical inhibition. Such powders are typically treated to reduce the risk of moisture degradation.

A recent development in dry fire extinguishers is the potassium aerosol fire extinguisher, in whirh a finely dispersed potassium containing dust [for example a potassium carbonate dust generated by a pyrotechnic decomposition of potassium nitrate with a carbon source, for example nitroguanidine httn://www.dynarneco,com/index.chn/technologv.htnil] is produced as an aerosol which acts to suppress a fire by the potassium acting to inhibit free radicals, so interrupting the chain reaction of the fire process.

JP2001-03790 discloses the use of breakable containers for an extinguishing powder comprising urea, ammonium chloride, sodium carbonate, sodium silicate, ammonium sulphate, alum, and a flurochemical surfactant. This material is used as a foaming material that extinguishes fires through the generation of carbon dioxide, foam, and ammonia which has a cooling effect on the fire. The containers ofJP200l-03790 may break spontaneously if the temperature rises enough, may be thrown at a fire so that the powder covers the fire, or may broken by hand into a bucket of water to provide added fire extinguishing effect to the water.

The applicants have found that by use of solutions of urea and potassium carbonate/bicarbonate fire-extinguishing compositions can be provided that may be used against a range of fires including Classes A, B and F. Accordingly, the present invention provides a fire-extinguishing composition comprising urea and a potassium containing compound selected from potassium carbonate and potassium bicarbonate in a liquid carrier.

Independently, and in combination, the invention further provides a delivery system for fire-extinguishing compositions for use in Class F fires.

Further features of the invention are set out in the appended claims and in the following non-

limitative description and drawings in which:-

Fig. 1 is a photograph of a sachet of fire-extinguishing composition according to one aspect of the invention; Fig. 2 a photograph of a bottle of fire-extinguishing composition according to a further aspect of the invention; and Fig. 3 is an exploded perspective view of a handle for housing a sachet of fire-extinguishing composition according to a further aspect of the invention.

In Fig 1 a sachet 1 is shown for use in dealing with cooking oil or fat fires. The sachet 1 forms a container for the fire-extinguishing composition. The sachet is made of a material that can readily melt or decompose at the typical temperature of a cooking oil fire [generally 280CC to 390°C]. Suitable materials for the sachet include foils of polymeric materials which maybe metallised. For example a three layer laminate comprising:- * a 2pm thick film of polyethylene terephthalate [PET] as an outer layer; * a 12 m thick intermediate layer of vacuum deposited aluminium; and

A-

* a 50 im thick film of linear low density polyethylene [L-LDPE] as an inner layer.

The detailed materials used for the sachet are not critical provided they meet the requirements of retaining the fire-extinguishing composition.

In use, in the event of fire, the sachet is placed in the burning oil. The heat of the burning oil melts or decomposes the sachet so that the fire-extinguishing composition is released and spreads across the surface of the oil to quench the flame. The fire-extinguishing composition is either a liquid or of a form that liquefies on exposure to the heat of the fire [e.g. a frozen liquid or a gel]. Preferably the fire-extinguishing composition is liquid.

Generally it is desirable that the sachet is thin skinned so that melting or decomposition takes place rapidly in the fire. However, this can result in a sachet that is liable to slump under its own weight Such slumping makes it difficult to place the sachet in the fire without the user getting their hand too close to the fire. To avoid the sachet slumping in use, and to provide an easier method of handling, a support may be used.

In Fig.1 a support 2 in the form of a piece of card is shown. This may be either adhered to the sachet 1, or secured in other ways [e.g. by a band or sleeve holding the sachet 1 to the support 2]. Other forms of support can be envisaged [e.g. a tube or box housing the sachet].

The support may have perforations to permit easy access of cooking oil or fat to the sachet when used.

Such a support is shown in to Fig. 3 which shows a complementary pair of half supports 7 which interengage to form the support. The support comprises a handle end 8, an immersion end 9 and an optional splash guard 10. The immersion end 9 includes optional fluid release apertures 11, and the handle end may include a thumb marker or other form of grip or indicator to inform the user so that it is readily apparent which end of the support is intended to be held and which is intended to go in the fire. An indicator may additionally or alternatively be placed on the immersion end. The half supports may be made of any suitable material or materials, for example a fire resistant plastic. It will be evident to the skilled person that although the support is shown as two, broadly similar, halves other support structures are possible [e.g. a channel with a cover plate].

In use a sachet is p'aced between the half supports 7 and housed in a channel 13 that extends from the immersion end 9 into the handle end 8. The sachet may be stored in such manner until needed.

In the event of a cooking oil fire the immersion end 9 is placed into the cooking oil, and the user can leave it there while departing the fire.

Optional splash guard 10 serves both to protect the user's hand from splashes of oil and to provide protection from flame. Additionally, splash guard 10, by providing additional material near the centre of the support, reduces the risk of the centre of gravity of the support moving into the handle as fluid is released, which might otherwise risk the support falling out of the cooking oil fire. A half guard may be provided rather than a guard around the whole of the support so as, in use, to bias the support to move into the fire.

Optional fluid release apertures 11 serve both to permit cooking oil to reach the sachet quickly [ensuring rapid heating of the sachet] and to permit ready release of the fire-extinguishing composition on melting or decomposition of the material of the sachet. If the immersion end 9 has an open end, such fluid release apertures are not necessary, but are desirable.

After use, the half supports 7 may be separated, the remains of the old sachet discarded, and a new sachet inserted into channel 13.

Alternatively, to avoid use of a separate support, the sachet may comprise thicker and stiffer regions, provided to provide a degree of rigidity, with thinner regions provided to permit easy escape of the fire-extinguishing composition in use.

In an alternative arrangement, a relatively stiff tubular container [e.g of waxed paper] may be provided at one end with an opening covered with a window of material [e.g as used for the sachet descried above] that can melt or decompose on exposure to a cooking oil fire.

In use, in the event of fire1 the end of the container comprising the window is placed in the fire so that the material of the window may decompose or melt in like manner to the sachet The composition may comprise potassium carbonate [or bicarbonate] and urea. Both potassium carbonate and urea are highly soluble in water so making the manufacture of a fire-extinguishing composition relatively easy by simple dissolution in water.

On use, the potassium carbonate both saponifies the fat, and evolves carbon dioxide. The urea decomposes to evolve ammonia and carbon dioxide. The water absorbs heat and generates steam. The ammonium carbon dioxide and steam generates, with the saponified fat, a foam that simultaneously reduces oxygen access and cover the burning surface of the cooking oil. The decomposition of urea and the vaporisation of the water absorb large quantities of heat, so cooling the fat. Whereas a spray fire extinguisher requires the presence of the user, delivery as a sachet or container placed into the cooking oil fire reduces the time when the user is close to the fire, so reducing the hazard.

The fire-extinguishing compositions contain both urea and potassium carbonate/potassium bicarbonate. The amount may be up to saturation, if the fire-extinguishing composition is a solution, or above saturation if the fire-extinguishing composition is a suspension.

Both urea and potassium carbonate have a solubility of >lOOg/lOOml at 209C. Potassium bicarbonate has a significantly lower solubility at -34g/lOOml. Accordingly, to get maximum potassium loading as a solution, potassium carbonate may be used. For a given loading of potassium, potassium bicarbonate can generate the maximum amount of CO2. Mixtures of the two enable the potassium/carbon dioxide ratio to be varied.

Typical compositions for the fire-extinguishing compositions comprise: Potassium bicarbonate and/or potassium carbonate 2-3Owt% Urea 2-30w1% Water 20-90w1% Other components and impurities O-6Owt% Under "other components and impurities" can be included ingredients such as detergents [to assist the foaming effect]; other fire retardant materials [for example ammonium phosphate, ammonium sulphateand or any other known fire retardant materials]; other saponifying chemicals [e.g potassium citrate or potassium acetate] and antifreeze [e.g. ethylene glyco]].

For Class A and B fires alternative delivery methods maybe used. Fig. 2 shows a "bomb" extinguisher comprising a bottle 3 of fire-extinguishing composition comprising a body 4 and cap 5. The bottle 3 has a narrowed waist 6 to assist holding in a grip ready for throwing. The bottle 4 may be of polypropylene or other suitable plastic material and is designed to shatter on impact, so that it may be thrown at the source of a fire, allowing fire extinguishing at a distance without the use of sprays.

For Class A and B fires, the gas-evolving effect of the urea and potassium carbonate act to assist dispersion of the fluid into a mist The saponifying effect of potassium is not relevant to a Class B fire, but in such a fire the finely dispersed mist of potassium acts to inhibit the chain reaction of the fire, in similar manner to a potassium aerosol fire extinguisher.

For Class A and B fires, it is generally useful to provide assistance from other fire retardant materials such as ammonium compounds [e.g. ammonium phosphate] to prevent re-ignition of the fire.

It can be seen that if sprayed at a cooking oil fire the compositions of the present invention can be used to provide both a quenching of the flame in the air [through the potassium aerosol effect] and at the surface of the cooking oil [through a saponifying effect] providing rapid extinguishing of the fire. Accordingly, the present invention includes not just the use of sachets [useful in a domestic or small scale context] but also the use of spraying [useful in a larger scale or industrial context] and delivery by means such as breakable "bombs".

Typical compositions for the fire-extinguishing compositions are:- ____________________________ Class F lire Class A/B fire Potassium bicarbonate 2-lOwt% 2-lOwt% Urea 2-lOwt% 2-lOwt% Ammonium phosphate 2-5wt% Detergent 1-Bwt% Anti-freeze (ethylene glycol) 2-ôOwt Water BO-YSwt% 20-4Owt% Specific examples are:-Class F sachet composition [wt%] Potassium bicarbonates±1% Urea 3.5±1% Water 91.5±2% Class A/B "bomb" composition [wt%1 Potassium Carbonate 6.5±1% Urea 3±1% Detergent 3±1% Ammonium phosphate5±1% Ethylene gycol 50±10% Water 30-45% Other compositions falling within the range of the claims are possible and may be tailored to meet the particular circumstances of fire type and environment

Claims

<claim-text>CLAIMS1. A fire-extinguishing composition comprising * urea; and * a potassium containing compound selected from potassium carbonate, potassium bicarbonate, and mixtures thereof in a liquid carrier.</claim-text> <claim-text>2. A fire-extinguishing composition, as claimed in Claim 1, having the composition:-Potassium bicarbonate and/or potassium carbonate 2-3Owt% Urea 2-3Owt% Water 20-9Owt% Other components and impurities 0-GOwt%.</claim-text> <claim-text>3. A fire-extinguishing composition, as claimed in Claim 2, in which potassium bicarbonate and/or potassium carbonate is present in the amount 2-iOwt%.</claim-text> <claim-text>4. A fire-extinguishingcomposition, as claimed in Claim 2 or Claim 3, in which urea is present in the amount 2-lOwt%.</claim-text> <claim-text>5. A fire-extinguishing composition, as claimed in any one of Claims ito 4, in which the other components comprising one or more components selected from the group, detergents, fire retardant materials, saponifying chemicals, antifreeze.</claim-text> <claim-text>6. A fire-extinguishing composition, as claimed in any one of Claims ito 5, comprising:-Potassium bicarbonate5±1% Urea 3.5±1% Water 91.5±2% 7. A fire-extinguishing composition, as claimed in any one of Claims ito 5, comprising:-Potassium Carbonate 6.5±1% Urea 3±1% Detergent 3±1% Ammonium phosphate5±i% Ethylene glycol 50±10% Water 30-45% 8. A method of delivering a fire-extinguishing composition, comprising spraying a composition as claimed in any of Claims ito 7.9. A fire-extinguishing composition, as claimed in any of Claims ito 7 housed in a container of breakable material.10. A method of delivering a lire-extinguishing composition, comprising throwing a container of breakable material as claimed in Claim 9.11. A fire-extinguishing article comprising a fire-extinguishing composition housed in a container comprised at least in part of a material capable of melting or decomposition at or below the temperature of a cooking oil fire.12. A fire-extinguishing article, as claimed in Claim 11, in which the container comprises a sachet 13. A fire-extinguishing article, as claimed in Claim 12, in which a support is provide to stiffen the sachet.14. A fire-extinguishing article, as claimed in Claim 12, in which a flame resistant handle is provided to or in which the sachet is mounted.15. A fire-extinguishing article, as claimed in Claim 14, in which the sachet is removably mounted to the handle.16. A fire-extinguishing article, as claimed in Claim 14 or Claim 15, in which the handle supports and stiffens the sachet.17. A tire-extinguishing article, as claimed in Claim 13, in which the sachet is housed in a channel within a fire resistant housing comprising a handle end and an immersion end.18. A fire-extinguishing article, as claimed in Claim 17, in which a splash guard is provided between the handle end and the immersion end.19. A fire-extinguishing article, as claimed in Claim 17 or Claim 18, in which fluid release apertures are provided in the immersion end.20. A fire-extinguishing article, as claimed in any of Claims 17 to 19, in which a thumb marker, grip, or indicator is provide to inform the user of which end of the support is intended to be held and which intended to go in the fire 21. A tire-extinguishing article, as claimed in any one of Claims 11 to 20, in which the fire-extinguishing composition is a composition as claimed in any one of Claims ito 7.22. A kit of parts comprising * a flame resistant handle or a fire resistant housing comprising a handle end and an immersion end; and * a sachet of fire-extinguishing composition; for making the fire-extinguishing article of any of Claims 14 to 21.23. A method delivering a fire-extinguishing composition to a cooking oil fire, comprising placing at least part of a fire-extinguishing article as claimed in any of Claims 11 to 21 into the burning oil.AMENDMENTS TO THE CLAIMS HAVE BEEN EILED AS FOLLOWSCLAIMS1. A fire-extinguishing article comprising a lire-extinguishing composition housed in a sachet comprised at least in part of a material capable of melting or decomposition at or below the temperature of a cooking oil fire, the sachet being: * mounted to a support in the form of a piece of card; or * housed in a support comprising a tube or box; or * mounted to or in a flame resistant handle the support or handle being capable of being placed at least in part into the burning oil of a cooking oil fire.
2. A fire-extinguishing article, as claimed in Claim 1 in which the sachet is removably mounted to the handle.
3. A tire-extinguishing article, as claimed in Claim 1 or Claim 2, in which the handle supports and stiffens the sachet.
4. A fire-extinguishing article, as claimed in Claim 1, in which the sachet is housed in a channel within a fire resistant housing comprising a handle end and an immersion end.
5. A fire-extinguishing article, as claimed in Claim 4, in which a splash guard is provided between the handle end and the immersion end.r
6. A fire-extinguishing article, as claimed in Claim 4 or Claim 5, in which fluid release apertures are provided in the immersion end.0
7. A tire-extinguishing article, as claimed in any of Claims 4 to 6, in which a thumb marker, grip, or indicator is provide to inform the user of which end of the support is intended to be held and which intended to go in the fire
8. A fire-extinguishing article, as claimed in any one of Claims 1 to 7, in which the fire-extinguishing composition is a composition comprising * urea; and * a potassium containing compound selected from potassium carbonate, potassium bicarbonate, and mixtures thereof in a liquid carrier.
9. A fire-extinguishing article, as claimed in Claim 8, in which the fire-extinguishing composition has the composition:-Potassium bicarbonate and/or potassium carbonate 2-3Owt% Urea 2-3Owt% Water ZO-9Owt% Other components and impurities O-6Owt%.
10. A fire-extinguishing article, as claimed in Claim 8, in which potassium bicarbonate and/or potassium carbonate is present in the fire-extinguishing composition in the amount 2-lOwt%.
11. A fire-extinguishing article, as claimed in Claim 8 or Claim 9, in which urea is present in the fire-extinguishing composition in the amount 2-lOwt%.
12. A fire-extinguishing article, as claimed in any one of Claims 8 to 11, in which the fire-extinguishing composition comprises other components comprising one or more components selected from the group, detergents, fire retardant materials, saponifying chemicals, antifreeze.
13. A fire-extinguishing article, as claimed in any one of Claims 8 to 12, comprising:-Potassium bicarbonates±1% Urea 3.5±1% Water 91.5±2%
14. A kit of parts comprising * a flame resistant handle or a fire resistant housing comprising a handle end and an immersion end; and * a sachet of lire-extinguishing composition; for making the fire-extinguishing article of any olClainis ito 13.
15. A method delivering a fire-extinguishing composition to a cooking oil fire, comprising placing at least part of a fire-extinguishing article as claimed in any of Claims ito 14 into the burning oil. rLID (0 iD</claim-text>