EP0909570A1 - Complementary charges for pulverised water fire extinguishers - Google Patents

Abstract

The new composition incorporates monopropylene glycol which imparts antifreeze properties down to - 45 degrees C. The new composition claimed is made up of (wt.%): diammonium phosphate, 7-11%; urea, 10 - 15%; ammonium sulfate,10 - 15%; citric acid,1 - 5%; monopropylene glycol, 20 - 25% and water to 100%. The composition is prepared by adding all the diammonium phosphate to the water, stirring at 50 degrees C, then half of the urea followed by all the ammonium sulfate.The citric acid is next added then the remainder of the urea and finally the monopropylene glycol, a corrosion inhibitor and, optionally, a dye.

Description

The invention relates to water extinguishers sprayed. It is more particularly intended for loads for such fire extinguishers.

The charge for a water spray extinguisher is obviously made up of water. Added to this are charges complementary to meet the various normative requirements for extinction, and others, non-normative such as freezing stability. The purpose of the present invention is to satisfy with a charge complementary, European standard EN 3 according to which the extinguisher ensures the extinction of typical hearths of class A (dry fires) and B (fires hydrocarbons).

Water spray extinguishers with a additional charge, such as mixtures of diammonium phosphate (DAP), urea, potash, and acid citric of US Patent 5,091,097, have good Class A fire extinguishing performance, but have no effect on class B fires and are not usable below -5 ° C. Likewise, compositions with base of DAP and an emulsifier, at least partly fluorinated, like those disclosed in European application EP-A-0676220 and which are active on lights A and B, cannot be used by freezing time, at least below -5 ° C. Fire extinguishers whose load includes ethylene glycol very resistant well at low temperatures but lose some of their performance on lights A or B. Mixed formulations concentrated, however, are not stable in temperature and undergo phase shift phenomena, which requires either the extemporaneous preparation of the agent fire extinguisher, i.e. the fractional incorporation of the charge additional by cartridge cartridges containing the ones fire extinguisher components, other components antifreeze, solution obviously impossible to apply in permanent pressure fire extinguishers.

The present invention overcomes these disadvantages by offering a single additional charge of type EN 3 for water spray extinguishers active on A or B fires, presented in a stable and dilutable concentrated formulation to will according to the desired degree of resistance to cold.

• Phosphate diammonique (DAP) 7 à 11 %,
• Urée 15 à 20 %,
• Sulfate d'ammonium 10 à 15 %,
• Acide citrique 1 à 5 %
• Monopropylène glycol 20 à 25 %
• Eau QSP 100 %

les pourcentages étant donnés en poids.The additional charge according to the invention consists of:

• Diammonium phosphate (DAP) 7 to 11%,
• Urea 15 to 20%,
• Ammonium sulphate 10 to 15%,
• Citric acid 1 to 5%
• Monopropylene glycol 20 to 25%
• 100% QSP water

the percentages being given by weight.

Such formulations can be diluted with water in all proportions. They have their own freezing point of the order of -40 ° C, and do not phase out above this temperature.

The extinguishing agent which is constituted by the dilution aqueous products according to the invention is further compatible with fluorinated additives or emulsifiers that some fire extinguisher manufacturers incorporate it into doses of 2 to 5% in order to improve its performance on lights B, a good description of which can be found in the application EP-A-0676220.

Preparation of additional charges according to the invention is very easy since it consists of charging in a stirred reactor at 50 ° C., the entire water charge, to incorporate the ammonium phosphate with stirring, to add half of the load of urea then all of the ammonium sulfate feed; then incorporate the acid citric then the complement of the urea load; finally at add monopropylene glycol, an inhibitor of corrosion, and if desired, a dye.

Their implementation presents no difficulty. Depending on the desired freezing point (from -10 to -30 ° C), the additional charge dosage to be introduced into the extinguisher will be between 35 and 80% (by volume).

EXAMPLE 1

• Phosphate diammonique (DAP) 9 %
• Urée 17 %
• Sulfate d'ammonium 13 %
• Acide citrique 3 %
• Monopropylène glycol 22 %
• Eau 35 %

We make the following composition

• Diammonium phosphate (DAP) 9%
• Urea 17%
• Ammonium sulphate 13%
• Citric acid 3%
• Monopropylene glycol 22%
• Water 35%

The composition is presented as a solution homogeneous clear with a freezing point of -45 ° C about.

Its solutions in water (percentages expressed by volume) have the following freezing points: Composition Water Freezing point 80 20 -30 ° C 60 40 -20 ° C 35 65 -10 ° C

A 6 liter fire extinguisher charged with the solution aqueous at 35% of the composition extinguishes an 8A hearth and, after additivation at 2% by weight with an AFFF type foam concentrate, fireplace 113B. This result therefore complies with the condition minimum required by European standard EN 3-4.

EXAMPLE 2 (counterexample)

• Phosphate diammonique (DAP) 9 %
• Urée 15 %
• Sulfate d'ammonium 16 %
• Acide citrique 5 %
• Ethylène glycol 20 %
• Eau QSP 100 %

Is carried out under the conditions of Example 1, the composition

• Diammonium phosphate (DAP) 9%
• Urea 15%
• Ammonium sulfate 16%
• Citric acid 5%
• Ethylene glycol 20%
• 100% QSP water

This formulation, although close to the previous one, but outside the scope of the invention, partially crystallizes during storage at a temperature close to + 10 ° C.

Claims (1)

Composition intended to constitute an additional charge for water spray extinguishers, comprising: Diammonium phosphate (DAP) 7 to 11%, Urea 15 to 20%, Ammonium sulphate 10 to 15%, Citric acid 1 to 5% Monopropylene glycol 20 to 25% 100% QSP water, the percentages being given by weight.