Autoclaving

Autoclave: - The laboratory apparatus designed to use steam under regulated pressure is called autoclave. It is horizontal, rectangular, high pressure, high vac cum and high temperature steam sterilization. An autoclave is based upon downstream displacement principle where the steams enters in the chamber from the top, push the air down to remove it from the bottom of the sterilization.

It is commonly operated at steam pressure of 1.06kg/cm2 (151lbs in2) above the atmospheric pressure which corresponds to the temperature of 121*c with standard vac cum up to 26-28Hg mm. The medium exposed to temperature in excess of 121*c may not properly gel or may result in poor cell growth. Similarly the pressure should not exceed 20psi.

High temperature may lead to decomposition of carbohydrates and other components of the medium. The time of operation to achieved sterility depends upon the nature of the material being sterilized, the type of the container and the volume of the container.

For Example: - Utensils and rubber gloves in muslin wrappers will take 15 minutes for autoclave whereas Surgical packs in muslin wrappers, solution in Pyrex flasks, treatment trays will take 30 minutes.

The use of autoclave in the sterilization process has two advantages.

1. Reduction of formation of air pockets: If the autoclave at the pre vacuum stage (create vacuum, allow steam inside and so on again) the air removal and load is more effective because load gets gradually pre-heated. This reduces the time taken by load to attain the sterilization temperature.

2. Better drying sterilized product: After the sterilization cycle, when the vacuum is employed in the chamber for drying purposes, the it will reduce the drying time and it will give effective drying of fabrics and dressing. Because of the forceful evacuation of moisture trapped in these articles which increases the shelf life of fabrics items because if the sterilized fabrics are not dried and during the storage, if the vapour condense then they can get contaminated through air before use and microbiological growth will start in them making them unsterilized and thus useless.