Disinfecting methods (sterilisation- physical )

Disinfecting methods (sterilisation- physical ):

Dry heat:

Sterilizing of glassware including syringes is often done in a hot air oven at 160⁰c for one hour.

Spores as well as organisms are killed. Rubber articles will not withstand this heat.

This method is not efficient where heat has to penetrate as in dressings, towels and gowns.

Moist heat : Autoclaving (Steam under pressure):

1.     This is a reliable method and may be used for most articles.

2.     The autoclave is a chamber with an outer jacket and a lid or door, which can be firmly clamped.

3.     Steam, is generated by heating water in a boiler or in the outer jacket.

4.     Air is evacuated from the chamber by displacement.

5.     Then the steam is allowed to build up pressure, usually 15 to 20 lbs per square inches, and is kept at that pressure for 15 to 30 minutes.

6.     Then the heat is turned off and the contents of the autoclave allowed to dry out.

7.     They should be quite dry when removed from the autoclave.

Points to remember:

1.     All articles should be clean and dry before packing. Any organic matter such as blood or pus prevents penetration of steam.

2.     The holder in the drums must be open when placing into the autoclave and closed immediately on taking them out.

3.     Bundles should be neither be too large nor be too tightly packed. Steam should be able to penetrate to the center.

4.     Rubber gloves cannot withstand high temperature and long sterilising. Autoclave them separately at 15 lbs pressure for 15 minutes.

5.     To autoclave bottles of fluid, loosen the screw cops, evacuate the steam slowly.

Boiling:

       I.            This  method  is  suitable  for enamel,  metal,  glass and rubber ware.

    II.            Bowl sterilizers are used for larger articles and instrument sterilizers for smaller articles.

Points to remember:

1.     See that the articles are quiet clean and completely immersed in clean water.

2.     When the water boils, start timing. If more articles are added, the sterilizing time must begin again.

3.     Boil for 5 minutes.

4.     Boiling will not kill spores

5.     Remove articles with sterile cheatle or other lifting forceps, and place them on a sterile surface.