FIREFIGHTERS and aircraft makers could benefit from a newly patented chemical
system that creates vast quantities of cool gas without using enormous
pressurised gas cylinders.
Right now, fire extinguishers and emergency chutes on aircraft need large,
heavy cylinders to hold the gases. These make extinguishers and chutes heavy and
hard to use, adding weight and wasting fuel in aircraft.
But Russian and Dutch scientists have developed a system that replaces the
hefty nitrogen tanks. It weighs half as much and occupies half the volume, says
Ronald van den Berg of the Dutch research lab, TNO, who’s been commercialising
the process with the Russian inventors.
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The reaction uses a block of a nitrogen-rich sodium azide compound that
decomposes when heated by a detonator, generating hot nitrogen gas. But
cleverly—and the inventors won’t say how—the heat of the gas is
absorbed back into the permeable solid, raising its temperature so that the
reaction can continue. And the gas can be released at temperatures as low as
room temperature. As a comparison, azides in car airbags produce gases hotter
than 150 °C.
“This new design doesn’t need heat exchangers to cool the gas,” says van den
Berg, “and the reaction can last for several minutes.”
Mike Hill of Sussex University, who has studied azides, says: “Controlling
the rate of the reaction is clever. Azides are generally shock sensitive and
they can decompose spontaneously and explosively.”
