Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
  • A62D1/0071—Foams
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S516/00—Colloid systems and wetting agents; subcombinations thereof; processes of
  • Y10S516/01—Wetting, emulsifying, dispersing, or stabilizing agents

Definitions

• the invention relates to liquid systems containing surface active substances which are suitable for forming fire combatting and extinguishing foams.
• fires particularly fires of fuels and propellants, are combatted by spraying foam in the form of continuous coats or coverings.
• foam blankets are also suitable for preventing the initial formation of fires.
• the required foam is customarily obtained by foaming aqueous solutions of foam forming substances.
• the solutions sometimes also contain foam stabilizers.
• Suitable prior art foaming agents for such purposes are often times prepared from proteins. For this purpose, it is thus known to use keratins, albumins, seed flour, and similar protein containing substances which are modified by hydrolysis and stabilized with certain preselected metal salts.
• foaming agents produced from protein hydrolysates cannot successfully be used for combatting certain types of fires.
• foaming agents are not suitable for fighting fuel fires or fires of polar substances such as, for example, alcohol fires.
• a further drawback of these known foaming agents resides in the fact that they are incompatible with dry fire extinguishing powders which are customarily used simultaneously, particularly if the powders have silicon containing surfaces.
• foaming agents which are water soluble, ionogenic derivatives of fluorocarbonor fluorosulfonic acids.
• Foaming agents or concentrates of this kind have been described, for example, in German Pat. No. 1,216,116.
• the latter type of prior art foaming agents is not fully satisfactory. It has thus been found that foaming agents of the indicated kind do not readily form stable aqueous foams of high expansion rate.
• a is a number of from one to three
• X is hydrogen or Y
• Y is a hydrophilading group, particularly polyethyleneglycol or a group containing an aminoxide -or ammonium salt group. It has also been suggested to produce fire fighting foams of desirable characteristics by employing foam concentrates which contain from to 100% by weight of a water soluble, surface active organosilicon compound (see U.S. Pat. application Ser. No. 865,171, filed on Oct. 9, 1969).
• Another object of the invention is to provide a liquid foaming agent system which contains an ingredient which considerably enhances the fire fighting characteristics of the foam and whose beneficial effect is essentially independent from the nature of the foam forming substances proper.
• aqueous fire fighting systems if the aqueous system contains between about 1 to 10% by weight of finely dispersed silica (SiO Particularly advantageous results are obtained if the silica is in colloidally dissolved form.
• colloidally dissolved silica contains as a rule a certain amount of OH-groups which impart to the system hydrophilic characteristics to a desirable extent.
• a most surprising feature of the present invention is that the silica can be beneficially incorporated in a large variety of aqueous fire fighting systems without affecting the foam forming substance or substances per se.
• the silica is thus essentially inert to the foam forming substance and does not negatively affect the foaming action but rather acts synergistically so as to impart the foam with desirable characteristics which would be absent in the absence of the silica.
• the fire extinguishing effect of the silica is es sentially independent from the nature of the particular foam forming agent used in the system. The same applies to systems which contain foam stabilizers.
• the fire combatting characteristics of foams can be successfully enhanced by the addition of the silica, irrespective of the nature of the foaming agent.
• the foaming agent proper is a protein hydrolysate or a fluorine containing surface active agent is irrelevant, since in both cases the addition of the silica significantly increases the fire combatting characteristics.
• the foaming agent proper is an organosilicon surfactant.
• the presence of the silica in the system not only enhances the fire fighting characteristics but also significantly increases the foam stability, whereby the so-called half value time is considerably increased.
• Foams produced from the inventive aqueous foaming systems are more economical since with a given amount of foam larger burning areas can be combatted than was possible with prior art foams devoid of silica. In addition, the fires are extinguished more rapidly.
• silica may be directly added to the aqueous foam concentrates.
• silica in powder form during the foaming of the foaming agent proper.
• foaming agent and/or foam stabilizer may be mixed with finely dispersed silica in dry form, whereby a powder is obtained which is then added to water for forming the foam. It will be appreciated that a foam forming agent in dry form which contains the silica incorporated therein, can be stored more economically than a liquid concentrate.
• HVT in the Tables stands for half value time and indicates the time period which passed until an amount of liquid had been reformed which corresponded to one half of the original amount.
• the height of the foam was measured in millimeter.
• the foam produced according to the impact foam test as described was moreover used for combatting and extinguishing fires of supergasoline according to two different methods.
• the first method I I ccm of these liquids were in each case fed to a pot of a diameter of 14.5 cm. The liquids were then ignited and after a burning time of 2 minutes, the extinguishing or fire combatting procedure was initiated.
• This method I was also used in some instances for combatting ethanol fires.
• 1000 ml of the combustible liquid were in each case fed into a high rectangular tub of a base surface of l l X I8 cm.
• the tub was provided with an inlet pipe below the liquid level through which pipe the fire fighting foam, after ignition of the liquid and a combustion time of 2 minutes, was pressed towards the burning surface.
• the extinction time was the time interval between the feeding of the foam towards the burning surface and the extinction of the flame. This test serves the purpose to imitate conditions which often times occur in the fire com-
• the formulation numbers indicated by are comparison tests in which no silica was used.
• formulations l 17 the substances were dissolved in water in the indicated sequence.
• formulation 18 a tenside containing powder was dispersed in water.
• Type Amount Type Amount weight 7r weight 7 l 1 2 26.5 3 21.3 1 A z 4 33.9 2 A 2 L 1 5 27.1 3 A 2 L 10 6 18.3 4 A 2 P 1 7 23.4 5 A 2 P 3 8 3; o A 2 P 7 9 33.0 7 A 2 P 4 I2 does not extinguish s A 1.5 P 4 13 57.0 9 A 0.5 P 4 I4 does not extinguish III I/ In each case, 70 ml of liquid were foamed and used for fire fighting. Only in formulations l2 and 13 210 ml of liquid were used.
• the aqueous composition contains between about I to 10% of finely dispersed silica.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Fire-Extinguishing Compositions (AREA)

Applications Claiming Priority (1)

Publications (1)

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Country Status (4)

Cited By (8)

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Citations (5)

• 0
  • BE BE756416D patent/BE756416A/fr unknown
• 1970
  • 1970-09-18 NL NL7013807A patent/NL7013807A/xx unknown
  • 1970-09-29 US US76602A patent/US3655554A/en not_active Expired - Lifetime
  • 1970-10-05 FR FR7035822A patent/FR2064982A5/fr not_active Expired

Patent Citations (5)

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