Potentially hazardous scenarios for fire fighters could soon be reduced, after The Linde Group announced an innovative process for extinguishing large scale smouldering fires.

The new process is achieved by injecting liquid carbon dioxide through a specially designed nozzle, sealing off the fire and reducing the risk for those fighting the fire.

Dangerous fires in silos storing organic material, such as wood chips, grain and increasingly raw material for biofuels, are unfortunately frequent events. Extinguishing such fires can be highly dangerous and has resulted in deaths of fire fighters in the past. Smouldering fires often begin when moist organic matter starts to ferment, with fermentation creating heat which can lead to a potentially explosive, smouldering fire.

Michael Heisel, Project Manager Refining and Process Chemistry for Linde Gases Divison, spoke of the benefits of the new system as he said, “Our new carbon dioxide extinguishing process will not only significantly reduce the risk of explosion, increasing safety for fire fighters, but because it is a clean agent any material which is not burned by the fire can remain undamaged, maintaining product value.”

With Linde’s new process a smouldering fire in a container is sealed off by a blanket of carbon dioxide injected through a proprietary nozzle. As carbon dioxide is heavier than air, it sinks to the lowest level once injected into a silo and as the fire continues underneath, the remaining air is consumed, creating a downwards vacuum. Carbon dioxide fills the vacuum and stifles the fire as the injected gas itself does not burn.

Additionally, the carbon dioxide efficiently catches sparks from the fire and extinguishes them, further reducing risk of explosion. The method can also be applied from a distance, protecting fire fighters.

Traditional methods of fighting large smouldering fires have until now been limited to the use of water and nitrogen, neither of which has produced optimal results.

Linde is optimising the methods of storage and transportation of the liquid carbon dioxide, including utilising small storage tanks at large silo sites or mobile tanks placed strategically at fire stations covering rural areas.