What is Dry Heat sterilization (DHS)?

This process of thermal sterilization is suitable for heat-stable, non-aqueous products and powders. The reference conditions are a minimum of 160° for at least 2 hours; other combinations of time and temperature may be used provided that it has been satisfactorily demonstrated that the process chosen delivers an adequate level of lethality when operated routinely within the established tolerances. The procedures and precautions employed should be such as to give a SAL of 10-6 or better.

The process of sterilization is carried out by a batch process in an oven specially designed for that purpose. The oven is supplied with heated, filtered air, distributed uniformly throughout the chamber by convection or radiation employing a blower system with devices for sensing, monitoring, and controlling the critical parameters. The sterilizer is loaded in such a way that a uniform temperature is achieved throughout the load. 

The temperature-sensing elements are inserted into representative containers together with additional elements at the previously established coolest part of the loaded sterilizer. An acceptable range in temperature in the empty chamber is ± l5° when the unit is operating at not less than 250°. Where the unit is employed for sterilizing components such as containers intended for intravenous solutions, care should be taken to avoid accumulation of particulate matter in the chamber. A SAL of 10-12 is considered achievable for heat-stable articles or components.

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