Do usual spray fire extinguishers contain liquid nitrogen? Why don firefighters use liquid nitrogen instead?
There are many different types of fire extinguishers depending upon their intended use. Home fire extinguishers are rated for A,B or C fires, and usually contain baking soda, or an equivalent powder. Fire Class Geometric Symbol Pictogram Intended Use A Green Triangle Garbage can and wood pile burning Ordinary solid combustibles B Red Square Gasoline can with a burning puddle Flammable liquids and gases C Blue Circle Electric plug with a burning outlet Energized electrical equipment D Yellow Pentagram Burning Gear and Bearing Combustible metals K Black Hexagon Pan burning Cooking oils So the answer to your first question is NO, spray fire extinguishers do NOT use liquid N2. Liquid N2 is not used for a number of reasons: Liquid N2 must be kept refrigerated at very low temperatures: -321F, or -196C. Liquid N2 can cause serious harm to human tissue- frostbite When liquid N2 vaporizes, it forms N2 gas which is an asphyxiant, as it will displace the oxygen in the local atmosphere– actually
