A device that heats liquid gases in a vaporizer/boiler until they vaporize (turn into gas). Simply put, cold liquid gases become gaseous after passing through a "vaporizer." The heating can be indirect (steam-heated vaporizer, hot water bath vaporizer, natural ventilation air bath vaporizer, forced ventilation vaporizer, electrically heated vaporizer, solid heat conduction vaporizer, or heat transfer fluid), or direct (hot gas or immersion combustion). The vaporizer shown in the right figure is an example, an air bath vaporizer.