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鈥檚 been commercialising
the process with the Russian inventors.
Advertisement
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鈥攁nd the inventors won鈥檛 say how鈥攖he 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 掳C.
鈥淭his new design doesn鈥檛 need heat exchangers to cool the gas,鈥� says van den
Berg, 鈥渁nd the reaction can last for several minutes.鈥�
Mike Hill of Sussex University, who has studied azides, says: 鈥淐ontrolling
the rate of the reaction is clever. Azides are generally shock sensitive and
they can decompose spontaneously and explosively.鈥�