Dry Heat Sterilization

This process is utilized to kill the microbes on the surface area. It is used to sterilize glassware, metal instruments and other heat stable solid materials which are not charged by high temperatures. Objects containing cotton, papers or plastic cannot be sterilized by this method because the high temperature will dull the cutting edge.

Approximately, one hour of heating up period is allowed for the entire load to reach the sterilization temperature.

Dry heat requires a much greater duration and intensity because heat conduction is less rapid in dry than the moist air. bacteria can survive in completely desiccated state and in this state the intrinsic heat resistance of vegetative bacterial cell is greatly increased, almost the level characteristics of the spores.

The death rate is much lower for dry cells than for fully hydrated ones.

There are two types of Dry heat sterilization.

1. Flame
2. Incineration

Flame: - Any object such as a needle which can be heated to red heat will be rendered sterile. Red heat is positively assurance of sterility, of course such sterility will remain only so long as the cooled, sterile object is not contaminated.

Incineration: - (Oven based sterilization) It regulates the temperature 200*c for 2 hours. Medium in oven is air.