What is the purpose of a thermostatic air vent in a steam sterilizer?

The purpose of a thermostatic air vent in a steam sterilizer is to automatically remove air from the sterilizer chamber during the initial stages of the sterilization cycle. This is crucial because, as explained previously, the presence of air interferes with the sterilization process by creating cold spots and hindering steam penetration. A thermostatic air vent operates based on the temperature difference between air and steam. It contains a temperature-sensitive element, often a bellows or a bimetallic strip, which expands or contracts in response to temperature changes. When the sterilizer cycle begins and the chamber is filled with a mixture of air and steam, the vent is open, allowing both air and steam to escape. As steam enters the chamber and the temperature increases, the thermostatic element heats up and expands. Once the element reaches a predetermined temperature, close to the temperature of saturated steam, it closes the vent. This prevents further steam from escaping, ensuring that the chamber is filled with pure, saturated steam for effective sterilization. The vent automatically opens again if the temperature drops, allowing any remaining air or non-condensable gases that may accumulate during the cycle to be removed.