PYROTECHNIC GAS-GENERATING COMPOSITION

Abstract

A gas-generating pyrotechnic composition has a high gas yield while having reduced generation of condensable species and a limited combustion temperature.

Claims

1. A gas-generating pyrotechnic composition, comprising: a reducing agent, 5-aminotetrazole, present in a mass content comprised between 10% and 30%, an oxidizing agent comprising alkali metal nitrates, alkaline-earth metal nitrates or mixtures thereof, said oxidizing agent being present in a mass content comprised between 30% and 75%, and an endothermic agent comprising sodium oxalate, strontium oxalate, copper oxalate or mixtures thereof, said endothermic agent being present in a mass content comprised between 10% and 50%.

2. The composition as claimed in claim 1, wherein the oxidizing agent comprises strontium nitrate, sodium nitrate or mixtures thereof.

3. The composition as claimed in claim 2, wherein the oxidizing agent comprises strontium nitrate.

4. The composition as claimed in claim 1, wherein the endothermic agent comprises sodium oxalate.

5. The composition as claimed in claim 1, said composition further comprising an agglomerating agent present in a mass content comprised between 1% and 6%.

6. The composition as claimed in claim 1, wherein: the reducing agent is present in a mass content comprised between 10% and 25%, the oxidizing agent is present in a mass content comprised between 35% and 55%, and the endothermic agent is present in a mass content comprised between 30% and 50%.

7. A gas generator comprising a gas-generating pyrotechnic composition as claimed in claim 1, and an initiator capable of initiating combustion of said composition.

8. An inflation device comprising a gas generator as claimed in claim 7 and an object to be inflated defining an interior volume in communication with an outlet of the gas generator.

9. A fire extinguisher comprising a gas generator as claimed in claim 7 and a body containing an extinguishing agent, the gas generator being adapted to pressurize the extinguishing agent so as to cause the extinguishing agent to be dispensed from the body.

Description

DESCRIPTION OF THE EMBODIMENTS

[0032] The inventors have evaluated the thermodynamic characteristics of various pyrotechnic compositions using the Ophelia calculation code. The formulations of the evaluated pyrotechnic compositions and the associated results are provided in the table below.

TABLE-US-00001 TABLE 1 Ingredients Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 5AT % 28.7 20.07 17.2 16.3 15.7 S  (NO3)2 % 71.3 49.93 42.8 42.7 41.3 Na2(C2O4) % / 30 40 40 40 Alumina % / / / 1 3 Thermodynamic characteristics Combustion temperature at 20 MPa K 2098 1769 1686 1623 1  86 Gas yield at 1 bar and 298K mole/kg 18.3 13.94 12.4  4 12.286 11.920 Particle rate at 298K % 43 53.78 57.36 58.  42 59.186 Density g/cm3 2.279 2.294 2.300 2.322 2.343 Gas yield by volume mole/  41.7 32.0 28.7 28.5 27.9 Oxygen balance % 8.1 2.1 0.1 0.6 0.5 Gas phase molar concentration at 1 bar - 298K CO2 ppm 184601 329971 400750 398927 4052  9 H2O ppm 30792 30792 30792 30792 30792 N2 ppm 646117 532581 66445 554125 550809 O2 ppm 138489 46655 2011 16153 13131 total ppm 9  9999 999  9 99  998 9  9997 1000000 Non-condensable gas rate % 96.9 96.9 96.9 96.9 96.9 % condensable H2O % 2.0 1.3 1.1 1.8 1.6 % N2 % 64.6 59.3 56.6 55.4 55.1 indicates data missing or illegible when filed

[0033] The composition according to Example 1 corresponds to a composition outside the invention. The compositions of Examples 2 to 5 correspond to compositions according to the invention. The compositions according to the invention have a lower condensable H.sub.2O content and a lower combustion temperature than the composition of Example 1, while maintaining a satisfactory gas yield.

[0034] The expression “comprised between . . . and . . . ” should be understood to include the bounds.