Pyrotechnic Cold Gas Generators for Underwater Rescue Systems and Heavy Duty Lifting

摘要

Pyrotechnic gas generators have been developed which consist of a two chamber system containing a pyrotechnic gas generating propellant in the first or combustion chamber together with a dense commodity of granules from an endothermic cooling agent placed in the second or cooling chamber. The system consist of a hot burning AN/PU or AN/GAP gas generating propellant with the exhaust gases flowing through a throat and nozzle into a dense packaging of granules from an oxalate or carbonate cooling agent which undergoes an endothermic gaseous decomposition and thus consumes the heat from the exhaust gases of the first propellant. By this way maximum temperatures of 80X or at least <250 °C are achieved for a gas delivery of 13 s and 18 s inflation time. With 660 g AN/PU end burning propellant grains about 780 I gas with an average temperature of 30 °C and several amounts of condensed water have been produced 10 min after the inflation of a 240I plastic bag. With 490 g AN/GAP end burning propellant grain 625 I gas and ca. 160 ml condensed water with an average temperature of 35 °C have been produced and used for the inflation and pres-surization of a metal bag boot. For a 6.5 I bag volume the maximum pressure reaches 110±5 bar after 15+3 s burning of the propellant grain. After 15 min the bag pressure has decreased and remains nearly constant at 73 bar. The load of roughly 11 t has been lifted to a height of 130 mm and stays there until the gas pressure is released by opening a tap or valve in the connecting hose between gas generator and the metal bag. The gas generating system has been adapted to the inflation of plastic bags for application as an underwater rescue system as well as for inflation and pressurization of a metal bag boot for lifting heavy loads up to 201 and more to save persons being covered by heavy debris from earthquakes or big accidents.