AUTOCLAVE

· Autoclave is a modified pressure cooker or boiler.

· It a vertical or horizontal cylinder of gunmetal or stainless steel in 'a supporting iron case.

· Heating is done through electricity.

· When water is heated inside autoclave it produce high pressure steam which kill the microorganism.

· Autoclave is commonly useful in laboratory, hospitals and industries.

PRINCIPLE

· Principle is based on moist heat sterilization method, Moist Heat kills the organisms by Denaturation and Coagulation of protein (DC).

· Principle applied in autoclave-

· Note - At normal pressure water boils at 100°C but when pressure inside a closed vessel increases, the temperature at which water boilis also increases. When steam comes into contact with a cooler surface it condenses to water and liberates its latent heat to that surface, for example, 1600ml of steam at 100°C and at atmospheric pressure condenses into One ml of water releases 518 calories of heat.

COMPONENTS OF AUTOCLAVE

· Autoclave is a modified pressure cooker for boiler

· Consist a vertical or horizontal cylinder of gunmetal

· heating is generally done by electricity

· discharge tap for air and steam

· Pressure gauge

· Safety valve

PROCEDURE

· cylinder is filled with sufficient water

· material to be sterilized is placed on the tray

· The lid is then closed, and the screws are tightened to ensure an airtight condition, and the electric heater is switched on.

· The safety valves are adjusted to maintain the required pressure in the chamber.

· Once the water inside the chamber boils, the air-water mixture is allowed to escape through the discharge tube to let all the air inside to be displaced.

· The drainage pipe is then closed, and the steam inside is allowed to reach the desired levels (15 lbs in most cases).

· Now, the electric heater is switched off, and the autoclave is allowed to cool until the pressure gauge indicates the pressure inside has lowered down to that of the atmospheric pressure.

· The discharge pipe is then opened to allow the entry of air from the outside into the autoclave.

· Finally, the lid is opened, and the sterilized materials are taken out of the chamber.

STERILIZATION CONDITION

Temperature - 121℃

Chamber pressure - 15 lbs.psi

Holding time - 15 minutes

· Other conditions -

126℃ for 10 minutes (20 lbs.psi )

133℃ for 3 minutes (30 lbs.psi )

PRECAUTIONS

· Air must be allowed to escape from the Chamber as temperature of air steam mixture is lower than that of pure steam

· Material should be arranged in such a manner as to ensure free circulation of steam inside the chamber

· The items placed inside the chamber should not touch the sides or top of the chamber.

· The wastes and clean items should be autoclaved separately.

· The liquid inside the containers should only be filled 2/3rd of the total volume to prevent the spilling of the liquid.

USES

· Sterilize culture media - liquid/solid not heat sensitive

· Pharmaceutical product, glass wares, biohazard waste

· Surgical instrument, gloves, rubber material, gowns

STERILIZATION CONTROL

· Physical - thermocouple

· Chemical - Browne's tube, autoclave tape

· Biological - spores of GEO-BACILLUS STEREOTHERMOPHILUA