Nitrogen compressed fire extinguishers contain nitrogen, compressed air, other gasses and a fire-extinguishing agent. Depending upon the type of extinguisher you have -- it may use foam or a dry chemical to retard the fire -- the nitrogen and other gasses work as the propellant.
High pressure cylinders operate with the air pressure over 500 pounds per square inch (psi). Low pressure cylinders operate between 40 and 499 psi.
Nitrogen compressed cylinders maintain a temperature of 70 F to work properly.
Despite extinguishers being designed to fight fires, compressed nitrogen extinguishers may explode or rupture if exposed to high heat. Lower the temperature of a overheated extinguisher by spraying it with water.
Although in the heat of an emergency you may not be able to find eye protection or gloves, it is best to protect yourself from the fire extinguisher chemicals as much as possible. Rinse off your skin immediately if is exposed to chemicals.