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
  • A62D1/0007—Solid extinguishing substances
  • A62D1/0014—Powders; Granules

Definitions

• the present invention relates to powdered fireextinguishing agents containing phosphates as their active fire-extinguishing component.
• Powdered fire-extinguishers are gaining increasing interest for use in fighting fire outbreaks occasioned'by liquids or tires, or fire outbreaks in electrical installations. The reason for this is more particularly that they often make the flames extinguish instantaneously, which is very advantageous. Still further, powdered fire-extinguishers of suitable composition produce on the ignited object a cover, which effectively prevents extinguished fire from: being revived, for example, by reignition caused by hot metal parts or glow residues.
• the fire-extinguishing powders which have more recently been used consist substantially of phosphates, which are more particularlyprimary or secondary ammonium phosphates, andhave the distinctionofcombining very good fire-extinguishing effects with'a very good covering power.
• the weight of these powders restricts their use in aircraft fire-extinguisher appliances or in fire-vehicles.
• ammonium polyphosphates having a degree of condensation between 200 and 500, preferably between 300 and 400.
• ammonium polyphosphates suggested to be used in accordance with the present invention have .an apparent density between about 0.4 and 0.9 kg/liter. As compared with conventional powdered fireextinguishers, it has been found that very substantial weight economies can be effected for an equally good fire-extinguishing power, using ammonium polyphosphates having the above degree of condensation and an apparent density between about 0.4 and 0.45 kg/liter.
• the above ammonium polyphosphates can be produced from polyphosphoric acid containing more than 76 weight percent P 0 preferably between 82 and 86 weight percent P 0 To this effect, the acid is heated to temperatures between 8 and 100C and gaseous ammonia is introduced without any supply of further heat.
• the heat of neutralization set free produces a temperature increase in the reaction mixture, which is maintained, if desired by cooling, between 300 and 330C, preferably 310 and 320C, until thetemperature itself commences to fall below 300C.
• the reaction mixture is then allowed to stand, if necessary while supplying further heat, at temperatures between 230 and 270C, preferably between 245 and 255C, until formation of a viscous crystalline magma which practically ceases to absorb further ammonia.
• the resulting reaction product is then cooled, washed with cold water and dried at temperatures lower than 100C.
• the isolated reaction product is annealed for a period'of at least 15 minutes at to 320C in a gaseous ammonia atmosphere having between 1 and 5 percent by volume steam therein.
• Products with a mean chain length n between 100 and 400are obtained by annealing the isolated reaction product for a period of at least 15 minutes, at temperatures between 220 and 320C in apure ammonia atmosphere.
• novel fire-extinguishing powders are rendered hydrophobic and flowable in conventional manner, for example, by theadditionof small amounts of polysiloxanes or magnesium stearate, and are foam-compatible.
• EXAMPLE 1 A trough with a cross-sectional area of 1 square meter and 12 cmhigh was filled first with 5 liters water for levelling purposes, and 25 liters Diesel oil were poured thereonto. The Diesel oil was ignited, allowed to burn for 5 minutes and extinguished. The extinguisher was ammonium polyphosphate with a degree of condensation between 300 and 400 and an apparent density of about 0.4 kg/liter. Comparative tests were carried out using commercial dry fire-extinguishing powders, so-called ABC- and BCE-powders.
• ABC- powder is a mixture which substantially consists of primary and secondary ammonium phosphates and sodium bicarbonate; it is used for extinguishing fire outbreaks as defined by fire classes A, B and C.
• BCE- powder consistsof sodium bicarbonate and is used for extinguishing fire outbreaks as defined by fire clases B, C and E.
• fire clases B, C and E Fire class A combustible, solid organic materials; fire class B combustible liquids, fire class C combustible gases, fire class E electrical installations.
• the following average quantities of fireextinguisher were needed in a series of tests.
• the fire-extinguishers used comprised those specified in Example l and ammonium polyphosphate with a conden sation degree of about 100 and an apparent density of 0.8 kg/liter. The following quantities of fireextinguishers were needed:
• Ammonium polyphosphate degree of condensation between 300 and 400; 1500 grams apparent density 0.4 kg/liter Ammonium polyphosphate, degree of condensation 100; apparent 2200 grams density 0.8 kg/liter ABC-powder 3000 grams BCE-powder 2400 grams EXAMPLE 3 25 liters of a polar solvent-mixture placed in troughs similar to those used in the preceding Examples were ignited, allowed to burn for 2 minutes and extinguished. The following average quantities of fireextinguisher were needed:
• Ammonium polyphosphate; degree of EXAMPLE 4 Gasoline was poured over automobile tires identical as to origin and dimensions, which were ignited, allowed to burn for 4 minutes and extinguished. The following average quantities of extinguisher were needed: Ammonium polyphosphate; degree of condensation between 300 and 400; 200 grams apparent density 04 kg/liter Ammonium polyphosphate; degree of condensation I; apparent density 350 grams 0.8 kg/liter ABC-powder 550 grams,
• a round trough 20 cm wide, cm high and subdivided into two halves was used.
• a baby comete tube with a pouring elbow was used to introduce a commercial foam extinguisher thereinto.
• 8 Grams of a commercial fire-extinguishing powder were dusted onto the material in the first half of the trough and 8 grams powdered ammonium polyphosphate were dusted onto the material in the second trough half. The reduction of the foam layer height and the water separation under incident heat were observed. After 6 minutes, the commercial powder and the ammonium polyphosphate were found to have separated 96 and 98 milliliters water, respectively.
• the uncovered gasoline was allowed to burn for 20 seconds; The slide plate separating the gasoline from the foam was removed and the time needed for complete destruction of the foam layer was determined. About 9.5 minutes were needed in all three cases. A 15 min. destruction time was needed in a blank test, using merely foam.
• reaction mixture allowing the reaction mixture to stand at temperatures between 230C. and 270C. which are maintained, if necessary by supplying further heat, until formation of a viscous crystalline magma which practically ceases to absorb further ammonia;
• the said ammonium polyphosphate having an apparent density of between 0.4 and 0.45 kg/l and a degree of condensation higher than 300.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Fireproofing Substances (AREA)
• Fire-Extinguishing Compositions (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Cited By (12)

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Citations (3)

• 1969
  • 1969-06-02 NL NL6908369.A patent/NL162306C/xx not_active IP Right Cessation
  • 1969-06-03 GB GB2795769A patent/GB1238404A/en not_active Expired
  • 1969-06-06 BE BE734192A patent/BE734192A/xx unknown
  • 1969-06-06 FR FR6918819A patent/FR2010306A1/fr not_active Withdrawn
• 1971
  • 1971-11-17 US US00199761A patent/US3755163A/en not_active Expired - Lifetime

Patent Citations (3)

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