Steam and Sterilisation Flashcards
Why is steam used in sterilisation?
Steam carries a massive amount of energy
It is non-toxic
It can be re condensed and used again
Main ingredient is water
No waste produce except water
Why is steam good in creating pressure?
The volume of steam in comparison to the water used to generate it is in excess of a thousand times greater
This creates a huge amount of pressure within small confined spaces
What are the different types of sterilisers?
Type N - basic, also called autoclave
Type B - more robust, also called vacuum capable or porous load steriliser
Type S - specialist piece of machinery
Describe the process of a type N steriliser
Machine heats water in the chamber
As it turns to steam it passively forces the air from the chamber
What are the cons of the type N steriliser?
Process can leave pockets of air within the chamber
You cannot process wrapped instruments or channelled or lúmenes instruments
Describe pockets of air in a steriliser
Air can’t be heated or maintain temp the same way steam can
It is always a lower temp than the steam surrounding it
If something is contacting air, it isn’t contacting steam
This means anything that the air is in contact with might not achieve its sterilisation temp for the minimum required time
What pressure and temperature must a type N steriliser reach and for how long?
Between 134 - 137º for a minimum hold time of 3 minutes
Pressure - 2.05 - 2.35 bar gauge
After this the instrument has only been sterilised
It will not be sterile at the point of use
Describe the type B steriliser process
Firstly all air is removed from the chamber
After it fills the chamber with steam - this creates a vacuum
This allows steam to rush into the chamber meaning it effectively contacts all surfaces
It has the capability to penetrate wrappings of instruments and sterilise the instruments inside
What items can be used in a type B steriliser but not a type N?
Wrapped, channelled and lumened instruments
Porous items such as cotton wool swabs
What pressure and temperature must a type B steriliser reach and for how long?
Between 134 - 137º for a minimum of 3 minutes
Pressure - 2.05 - 2.35 bar gauge
Describe a type S steriliser
Washes and lubricates hand pieces that are being processed as well as sterilising them
Has a vacuum cycle but doesn’t process wrapped instruments
Achieves the same temp and pressure and has the same stage hold time of 3 minutes
Can only be used for the equipment it is designed to process
What daily tests should be carried out on a steriliser?
Checking door seals are intact and free from debris - clean if necessary
Verify the chamber is free from damage, debris, contamination or instruments from previous cycles
Verify the condition of the load carrier
Fill and drain the feed water reservoir each day
Drain the used water reservoir each day
What tests are specific to a type B steriliser?
Daily - steam penetration test using a test device such as a Bowie Dick test pack or a Helix
Weekly - an air leakage test, an air detector function test (ADFT)
