STERALISATION
Define -It is a process by which an article,surface or medium is made free of all microorganisms either in the vegetative or spore form
HEAT BASED
A)Moist Heat based
Heat is most relaible method of steralsition the most heat kills the bacteria by denaturation and coagulation of the cytoplasmic proteins
1)TEMP BELOW 100 oC
Vaccine bath -At 56 oC for 1hrs
Pasteurisation of milk -63oC for 30 min
2) TEMP ABOVE 100 oC
Boiling
Steam at atmospheric pressure at 100 oC for 90 min
Autoclave
Principles and procedure
Principle-
1)Water boils when vapour pressure = surrounding atmosphere
2)Pressure inside a closed vessels increase the atmosphere boils also increased to more 100 oC
3)The considered water ensure the moist conditions for killing of the microbes present
Procedure
1)Before beginning to use the autoclave, it should be checked for any items left from the previous cycle.
2)A sufficient amount of water is then put inside the chamber.
Now, the materials to be sterilized are placed inside the chamber.
3)The lid is then closed, and the screws are tightened to ensure an airtight condition, and the electric heater is switched on.
4)The safety valves are adjusted to maintain the required pressure in the chamber.
5)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.
6)The complete displacement can be ensured once the water bubbles cease to come out from the pipe.
7)The drainage pipe is then closed, and the steam inside is allowed to reach the desired levels (15 lbs in most cases).
8)Once the pressure is reached, the whistle blows to remove excess pressure from the chamber.
9)After the whistle, the autoclave is run for a holding period, which is 15 minutes in most cases.
10)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.
11)The discharge pipe is then opened to allow the entry of air from the outside into the autoclave.
12)Finally, the lid is opened, and the sterilized materials are taken out of the chamber.
Components
1) vertical or horizontal cylinder of gunmetal or stainless-steel
2)Lid
3)Electricity
USES
1) Culture media
2)Rubber articles like tubes,etc
3)syringes and surgical instrument
4)Endodontic instruments
5)Hand instruments
DRY HEAT STERALISTION
HOT AIR OVEN
-It is most widely used method of steralisation by dry heat
-It is also fitted a thermostat the maintaining the chamber air at a chosen temprature
160oC -2hrs
USES
1)Glass-wrapes like glass syringes flakes,tubes
2)Surgical instrument like scalples, scissors, etc
FILTERSTION AND. RADIATION
CHEMICAL METHODS
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