Compositions – Fire-extinguishing – Foam or gas phase containing
Reexamination Certificate
2000-04-14
2002-04-30
Anthony, Joseph D. (Department: 1714)
Compositions
Fire-extinguishing
Foam or gas phase containing
C252S008050, C106S018130, C106S018210, C106S018240
Reexamination Certificate
active
06379578
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aqueous film-foaming foamable fire extinguishing agent (fire foam) which provides excellent foaming power and film-forming properties in a low temperature range, especially an environment at −20° C. or below, further a temperature range at −25° C. or below.
RELATED ART
Conventionally, enhanced potassium carbonate and potassium hydrogen carbonate aqueous solutions are widely known as aqueous fire extinguishing agents. Such fire extinguishing agents extinguish fire with cooling and moisture (wetting)-permeability effects of water. They effectively prevent re-start of fire and provide a clear view to an operator during fire extinguishing. However, although the composition of such aqueous fire extinguishing agents excellently extinguish wood fire, these are said to be less effective to oil fires compared to powder fire extinguishing agents. Further, the above aqueous fire foams are strongly alkaline such that they are not very safe to humans and other animals.
Therefore, the inventor of the present invention previously invented a neutral fire extinguishing agent using ammonium phosphate (Japanese Patent No. 2,860,311).
Fire foams are mainly divided into ones for general oil fires, such as petroleum, gasoline, kerosene and the like, and ones of anti-alcohol type against fires of alcohols, ketones and the like. They include protein fire foams, synthetic surfactant fire foams and aqueous film fire foams.
To extinguish hydrocarbon fires, one suggests a fire extinguishing agent in which a thixotropic solution is formed by adding water-soluble polymers to a foam-film-forming condensate, which is made of a mixture of fluorinated surfactant, a hydrocarbon surfactant and foam-stabilizing solvent of the glycol group, or a fluorinated surfactant.
Japanese Examined Publication H6-2166 discloses an aerosol fire extinguisher using a fire extinguishing agent formed of potassium carbonate, a fluorinated surfactant and an aqueous solution of an anti-freezing agent. To improve the foaming power, the above publication also suggests to add lauryl alcohol sulfate ester, polyoxyethylene lauryl sulfate and the like as a hydrocarbon surfactant.
Japanese Examined Publication H6-2169 discloses an aqueous fire foam containing cationic water-soluble polymers, a polybasic acid, a metal salt having ionic valence of 2 or higher, and a surfactant containing an anionic hydrophilic group; one of embodiments of such a fire foam shows the solidifying point between −14° C. and −23° C.
Japanese Laid-open Publication H6-312030 discloses a water spray portable fire extinguishing agent containing fluorinated betaine, fluorinated amine oxide, alkyl glucoside, a non-fluorinated surfactant, monoalkyl ether of mono- or diethylene glycol; one of embodiments of such a fire extinguishing agent shows the freezing point of −22° C.±2° C.
Japanese Laid-open Publication H9-173498 discloses a fire foam in which a fluorinated surfactant expressed in a specific general formula is added to a synthetic surfactant fire foam.
Japanese Laid-open Publication H9-124884 discloses a foam condensate as an aqueous dispersed solution formed of water-insoluble fluorinated copolymers for fires of polar solutions such as alcohol and the like, a hydrocarbon surfactant, a fluorinated surfactant, and hydrophilic organic solvent.
Ammonium phosphate in the above fire extinguishing agent disclosed in Japanese Laid-open Publication H4-24032 is highly water-soluble wherein its aqueous solution indicates almost neutral pH (6.5 to 8); therefore, it is believed to be an excellent neutral fire extinguishing agent. However, a Japanese regulation requires a fire extinguishing agent to be usable at −20° C.; hence, the above fire extinguishing agent requires addition of a large amount of an anti-freezing agent and a solidifying point lowering agent.
Some of the anti-freezing agents and solidifying point lowering agents are hazardous substances such as class 4 secondary petroleum and tertiary petroleum compounds. Within a range of temperatures for the use of fire extinguishing agents required by the regulation between −20° C. and 40° C., the above fire extinguishing agent may result in volatilization and ignition at a high temperature while performance of the surfactant is lowered at a low temperature resulting in lowered foaming power and film-forming properties. This issue is a notable technological drawback.
As a result, the inventor of the present invention, considering the above issues, invented an aqueous fire foam which has excellent foaming power and film-forming properties at −20° C. or below, especially −25° C. or below (Japanese Laid-open Publication H6-218075). This invention disclosed in Japanese Laid-open Publication H6-218075 relates to an aqueous fire foam of pH 7.4 to 8 (at 20° C.) which has improved foaming power and film-forming properties in a low temperature range wherein an aqueous solution containing a solidifying point lowering agent, and at least one of potassium hydrogen carbonate and ammonium phosphate, added perfluoroalkyl betaine, and one of the following hydrocarbon surfactants: imidazolinium betaine; alkyl carboxyl betaine, N-acyl-N-methyl-&bgr;-alaninate as foaming and film-forming agent.
DESCRIPTION OF THE INVENTION
(Problems to be Solved)
An aqueous fire foam of the invention disclosed in Japanese Laid-open Publication H6-218075 is composed of a given composition such that the amount of a solidifying point lowering agent added is less than in a conventional one to improve the foaming power and film-forming properties in a low temperature range. However, the market demands an aqueous fire foam which is even more stable in a low-temperature range and which is applicable to both wood fires and oil fires.
(Means to Solve the Problems)
The inventor of the present invention discovered that the foaming power and film-forming properties in a low temperature range of an aqueous fire extinguishing agent can be dramatically improved by the following method. Such an aqueous fire extinguishing agent is formed by adding a solidifying point lowering agent to a solution containing at least one of the following to establish a solidifying point below −20° C.: potassium hydrogen carbonate; ammonium phosphate; ammonium sulfate; ammonium bromide; boron oxide; and potassium tetraborate. The following are also added together to such an aqueous fire extinguishing agent:
perfluoroalkyl betaine as a fluorinated surfactant; and
amide amino acid surfactant expressed by the below general formulas (1) and/or (2) (in the formulas: R
1
indicates an alkyl group having 7 to 23 carbons, a hydroxy alkyl group, an aralkyl group, or an alkenyl group; and X indicates an alkali metal or hydrogen atom) or a surfactant composition in which alkaline earth metal ions are added to the above surfactant as a hydrogen carbonate surfactant.
Ordinary surfactants tend to lose a function as an activator at about −10° C. or below, and, they show significantly deteriorated foaming power or even do not foam at all in a low temperature range (−20° C. or below). However, the foaming power can be improved in the low temperature range (−15° C. to −25° C.) by using perfluoroalkyl betaine and an amide amino acid surfactant which is expressed by the above general formulas (1) and/or (2) or a surfactant composition in which alkaline earth metal ions are added to the above surfactant. Also, such surfactants have the effect of promoting saponification in fatty acid ( dietary oil) fires.
At least one of the following is appropriate as a main component (of the aqueous fire foam of the present invention): potassium hydrogen carbonate; ammonium phosphate; ammonium bromide; boron oxide; and potassium tetraborate.
Ethylene glycol is one of widely adapted solidification point lowering agents. All solidification point lowering agents are combustible organic substances; the amount of the agent added must be minimal to prevent re-start of a fire. A preferab
Anthony Joseph D.
GTL Co., Ltd.
LandOfFree
Water-based foam fire extinguisher does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water-based foam fire extinguisher, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water-based foam fire extinguisher will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2917695