Abstract: Air indicating device for use in steam or gas sterilizers and the like includes an upright tube placed in the sterilizer. The tube is open at its bottom to the sterilizing chamber and is closed at its top. A heat sink within the tube causes steam entering the tube to condense with a resulting accumulation of air in the top of the tube. The air accumulation acts as a barrier preventing further steam from reaching the upper portion of the tube. A temperature sensitive indicator strip extending axially into the tube changes color responsive to temperature. The air barrier is also an insulator so that the color of the indicator is a record of the temperature gradient from the top to the bottom of the tube, the temperature, in turn, being a measure of the amount of air trapped in the tube.

Abstract: A signal generating and transmitting device is disclosed which can be placed within a load to be sterilized to continuously monitor sterilization affecting conditions at the center of the load. Radio signals representing the sensed conditions are transmitted by the device to an antenna in the sterilizing chamber, the antenna in turn being directly wired to a receiver outside the device which adapts these signals for controlling the operation of the sterilizer.

Abstract: Steam and entrapped air are bled from a steam sterilizing chamber and into a water displacement tube. The steam component of the bleed is condensed in the tube while any air entrapped in the steam displaces water from the tube. As the water level in the tube drops to a predetermined level, the tube is vented and the sterilizing chamber is pulse vented to introduce additional steam into the chamber. The method contemplates delaying the start of the sterilization period until a sufficiently low amount of air remains in the sterilizing chamber as determined by the intervals between repeated venting of the tube exceeding a predetermined timed interval.