Abstract: An apparatus for cooling a vessel containing molten metal has a quantity of liquid coolant atomized by a gaseous medium and onto a surface to be cooled. The supply of gaseous medium is constant while the supply of liquid coolant to the spray nozzles is controlled by at least one valve the operation of which is brought about by a non-electrical temperature responsive element in thermal contact with the surface to be cooled. The rate at which the liquid coolant is sprayed on to the hot surface is controlled such that the volume of coolant sprayed on to the surface to be cooled does not exceed the volume of liquid that is capable of being vaporized from the surface.