About Lesson
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AUTOCLAVES
An autoclave is a closed vessel in which steam is subjected to pressure that is greater than the atmospheric pressure. It is used for sterilization
Components of an Autoclave
- Autoclave chamberis made of a heavy cast metal.
- Tightly fitting lid withclamps and rubber seals.
- Metal packing drum which fits inside the autoclave chamber.
- Pressure valve set to open at the desired pressure.
- Safety valve through which steam may escape if the pressure inside the autoclave exceeds a set safety value.
- Pressure gauge indicating internal pressure
- Temperature gauge indicating the temperature of the steam
- The air outlet used to vent air outside whileheating and to also introduce air after sterilization
- A built in heating and water cooling system
- Replaceable rubber seal
How to use an Autoclave
- Caps of containers to be sterilized should be loosen , other items should be wrapped in porous brown paper and their edges carefully secured with autoclave tapes
- Place the containers and other items in a wire basket or in the autoclave drum.
- Pour distilled water or tap water into the autoclave drum to the level indicated by the manufacturer.
- Place the basket or drum containing the items to be sterilized in the autoclave.
- Close the lid and screw the lid clamps firmly and connect the horse to the air outlet.
- Switch on the autoclave electric or gas plug or place it on the suitable heat source e.g. charcoal jiko.
- As the water boils, a mixture of air and steam escape through the air outlet. leave it to escape for about 5min.
- Test if all the air has been expelled out by placing the other end of the horse inside a water bucket. the presence of air is indicated by bubbles , pure steam produce cracking sound as it condense into water
- When all air have been expelled , close the air outlet and watch the pressure and temperature gauge .when pressure reaches 15 psc , reduce the heat and leave it for the recommended sterilization time using a timer clock
- Turn off the heat and wait until the pressure gauge reach zero, open the outlet then open the lid and unpack.
- Some autoclaves have indicator strips on the autoclave tapes, which changes color after sterilization.
NB: indicator strips are sometimes not reliable.
Care and Maintenance of Autoclaves
- Follow the manufacturer’s instructions
- Always fill the autoclave with the correct volume of water. Irreparable damage may occur if the autoclave boils when it is dry.
- Do not use saltwater as these enhances rusting of the autoclave
- (iv) Lubricate the screw clamps with oil
- Clean the autoclave immediately after use
- Servicing must be carried out by experts only
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