Apparatus and method for sterilizing with vaporizable liquids

A sterilizing device includes a heating chamber having a reservoir containing a substantially inert, vaporizable liquid having a boiling point sufficiently high to kill microorganisms unsafe for humans. The sterilizing liquid is heated to boiling by a heater submerged therein. The articles to be sterilized are placed in a perforated tray located in the chamber above the reservoir and are contacted by a blanket of substantially saturated vapors of the sterilizing liquid. A temperature controller turns the heater off and on in response to the vapor blanket rising to and falling below a predetermined level above the tray. A counter counting the number of electrical impulses or cycles thereafter transmitted to the heater turns off the heater after a predetermined number of such cycles and a fan or similar cooling apparatus is energized to cool the chamber and condense the vapors. Vapors entrained in the air displaced from the chamber by the rising vapor blanket are either removed by a filter arrangement or collected along with the air in an inflatable member and returned to the chamber after completion of the sterilizing cycle.