Extinguishing and cooling a thermal oil fire
Thermal oil is used above its flash point in thermal oil systems. It is combustible. When there is a leak inside a thermal oil heater, e.g. in the coil, the thermal oil can burn. When ignited it will continue to burn even when the fuel burner is off, as long as there is enough oxygen and a continuous leakage of thermal oil.
There are two effective ways to extinguish such a fire, either with argon or with water mist. In both variants, the fire is extinguished by removing oxygen. When extinguishing with water mist, the fire is smothered with a fine water mist. In addition to the almost unlimited availability of water, the heat source is cooled down by evaporating the water droplets. A renewed ignition of the flames by the hot heat transfer oil will be prevented.