In every country around the world used tires accumulate in piles. Every year, through carelessness, accident or lightning, some of those tire piles catch fire. Currently there are only three ways of dealing with these disasters. Allow the pile to burn itself out, smother the fire with dirt, or use an expensive combination of water and a foaming agent to put the fire out. Tire fires put out enormous quantities of toxic smoke, soot and gasses so allowing to them burn does great environmental damage. Smothering them sometimes works, but often leaves the tires smoldering underground for years. The water and foam option puts out the fire, but causes additional problems because the foam, water and oil mixture eventually runs off and causes contamination of the ground water. In order to contain the run-off mixture, more equipment, manpower and mitigation measures are required. Thus, the water and foam approach entails much more cost, manpower and time than might originally have been assumed.
An alternative method of extinguishing the tire fire is to direct a stream of liquid nitrogen onto the burning tires. When the liquid nitrogen hits the hot surface of the tires, it immediately evaporates and expands by a factor of about 900x to form a ball of non-combustible nitrogen gas. That ball of gas immediately extinguishes the fire by preventing oxygen from reaching the burning tire. I have carried out this experiment and verified the efficacy of this technique on a small scale. The Liquid Nitrogen (LN2) does not explode nor cause any other hazardous actions. It simply extinguishes the fire. In addition as a further benefit the temperature of the tire surface is immediately lowered, reducing out gassing of any combustible or toxic gasses. Finally, using LN2 in this way produces no other gaseous or liquid pollutants such as the foam-water mixture so the act of extinguishing the fire will not further contaminate the fire site.
Liquid Nitrogen is more expensive than water, but when the cost of the foam, the foam application equipment, the manpower and the cleanup of the water-foam-oil mixture is included in the calculations, it becomes much more feasible. Furthermore, LN2 is available in almost all parts of the world and LN2 transport via refrigerated tanker trucks is a well-established industry.
In order to make this a viable method of extinguishing tire fires, research and development must be undertaken to optimize the nozzles, pumping systems, delivery pipes and strategies for application of the LN2 to the burning pile of tires. This is the work that needs to be done in order to bring to reality a method of fighting tire pile fires that will reduce dangers to the environment, to the fire fighters themselves, to the communities and to the world. Using this technique to extinguish tire fires will reduce pollution, increase safety and save lives both during the fire fighting operation and in the long term by reducing toxic pollution to the atmosphere and to the ground water.