Fire fighting foams utilizing saponins

Details Fire fighting foams utilizing saponins Fire fighting foams utilizing saponins

1999-03-10

2000-04-18

Brouillette, Gabrielle

Compositions

Fire-extinguishing

Foam or gas phase containing

252 805, 169 44, A62C 3102, A62C 200

Patent

active

060511540

DESCRIPTION:

BRIEF SUMMARY
FIELD OF INVENTION

This invention relates to fire fighting foams and, more particularly, to fire fighting foam formulations utilising saponins to significantly improve the heat resistance of these foam formulations, to serve as synergists to the surfactants used in these foam formulations, and more specifically, to substantially reduce foam formulation viscosity in alcohol resistant type foam formulations.


BACKGROUND ART

Saponins are a group of sapogenin glycosides obtainable from many plants. Each saponin consists of a sapogenin which constitutes the aglucon moiety of the molecule and a sugar. The sapogenin may be a steroid or a tri-terpene and the sugar moiety may be glucose, galactose, a pentose or a methylpentose. Aqueous solutions of saponins foam like soap on shaking and are used, inter alia, as detergent.
Saponins were used in very early fire fighting foams as foaming agents but have long since been discontinued due to their high cost, which makes them unsuitable for use as foaming agents, given the existence of cheaper alternatives.
Synthetic fire fighting foam formulations, such as aqueous film forming foams (of either the alcohol resistant type or non-alcohol resistant type), high expansion foams and class A foams (which includes forest fire foams) use a synthetic hydrocarbon surfactant or detergent as a foaming agent. Aqueous film forming foams (AFFF's), in particular, consist of both synthetic hydrocarbon surfactant foaming agents and a fluorocarbon surfactant added to lower the surface tension.
The basic concept behind AFFF formulations is that it is possible to float a film of water on top of a lower density hydrocarbon fuel if the surface tension is sufficiently low and the interfacial tension between the two liquids is in the appropriate range. The fluorocarbon surfactant is able to achieve this low surface tension.
Aqueous film forming foams also use a non-ionic hydrocarbon surfactant, which is usually of the ethoxylated octyl phenol type (such as TRITON X 102), in combination with the fluorocarbon surfactant to lower the level of fluorocarbon surfactant required. Without the addition of the non-ionic hydrocarbon surfactant, higher levels of the relatively expensive fluorocarbon surfactant is required. Alkyl polyglycoside surfactants can also be used to replace the ethoxylated octyl phenol type surfactant.
A typical 6% AFFF formulation of the prior art has the following general composition:


______________________________________ COMPONENT RANGE ______________________________________ Fluorocarbon Surfactant 0.5% to 2% Amphoteric Hydrocarbon Surfactant 1% to 5.5% Anionic Hydrocarbon Surfactant 0% to 2.5% Non Ionic Hydrocarbon Surfactant 0.5% to 2% Glycol/Glycol Ether 2% to 10% Buffer 0% to 2% Sequestrant 0% to 1% Corrosion Inhibitor 0% to 2% Water Balance ______________________________________
A limitation of hydrocarbon surfactants resides in the heat resistance of the foam produced. Furthermore, fluorocarbon surfactants are very expensive and not particularly environmentally friendly.
We have found that the use of low levels of a saponin can significantly improve the heat resistance of the foam and provide economic advantages in relation to the ability to use less amounts of other components of the foam. For instance, when low levels of saponins are used in an AFFF formulation, the non-ionic hydrocarbon surfactant is not required. Saponins have been found to be more effective than either ethoxylated octyl phenol type or alkyl polyglycoside type surfactants for this purpose. In addition, the saponin component replaces part of the hydrocarbon surfactant component of the foam. For saponin to completely replace the hydrocarbon surfactant would require a concentration of greater than 15% (by weight) in the foam concentrate formulation. (prior to mixing with water to form the foam formulation) and this is not currently practical or desirable as saponins are relatively expensive when compared to hydrocarbon surfactants. The use of saponin also enables a r

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Abstract for Japenese Publication 71006280. Assigned to Dailkin Kogyo, 1971.
Abstract for Japenese Publication 53145398. Assigned to Fudad Kogyo, Dec. 1978.

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