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US 4,060,489 AGranted
Fire fighting with thixotropic foam
AssigneePhiladelphia Suburban Corporation
InventorPeter J. Chiesa, Jr.
Life of this patent
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AssigneePhiladelphia Suburban Corporation
InventorPeter J. Chiesa, Jr.
Estimating the term…
Aqueous foam formed with solution containing thixotropic polysaccharide in addition to foaming agent, will gel when projected onto a burning hydrophilic liquid, and such foam is not destroyed by the liquid, so that it is suitable to fight fires on hydrophilic liquids as well as on hydrophobic liquids and on solids that are compatible with the foam. The thixotropic character enables the ready pumping of the foam and of the solution from which it is formed. A substantial content of N-methyl pyrrolidone-2 in a concentrate for such foam-producing solution can make such concentrate more adaptable for ready dilution and also improves its stability. Urea can be added to help solubilize the polysaccharide, and it will also reduce the viscosity of a concentrate. Other ingredients can also be included such as to form films over hydrophobic liquids to improve the stability of the foam that is formed and to increase the thixotropic action.
An aqueous pumpable fire-fighting concentrate for dilution with at least about ten times its volume of water and foaming with air to produce a fire-fighting foam, said concentrate containing (a) a foaming agent that causes the diluted concentrate to form a foam having an expansion of at least about 3, and (b) a water-soluble thixotropic polysaccharide dissolved in an amount that causes the foam to undergo syneresis and form a floating gel mat when applied to a non-aqueous polar solvent.
A fire-fighting composition which is essentially an aqueous solution of (I) a foaming agent that causes the composition to form a foam having an expansion of at least about 3, and (II) a thixotropic polysaccharide in a concentration that causes the solution to gel when contacted with a non-aqueous polar solvent.
Dependencies are inferred from the claim text.