Benchtop Autoclaves - Should I Be Buying B Class?

We often get asked for advice on whether to purchase a B class or an S class autoclave / steriliser and one of the first things is to know the difference between them. AS/NZS 4815 outlines the definitions of both hollow and sold instruments and this really determines whether you need a B class capable autoclave. Instruments fall into 3 different classes for sterilisation as below:

1. Solid Instruments - these are instruments that have no hollow or aperture that has a depth to width ratio equal to or greater than 1, for instance if your instrument has a cavity that is 10mm deep and is also 10mm in diameter then it is classed as a solid instrument.
2. Hollow B Instruments - these are instruments that have a hollow or aperture that has a depth to width ratio less than 1, for instance if your instrument has a cavity that is 10mm deep and is also 9 mm in diameter then it is classed as a hollow type B instrument.
3. Hollow A Instruments - these are instruments that have a hollow or aperture that has a depth to width ratio less than 1:5, for instance if your instrument has a cavity that is 10mm deep and is also 2 mm in diameter then it is classed as a hollow type A instrument.

Your autoclave works through removing air from the chamber though a series of vacuum pulses, injecting superheated steam into the chamber at a predetermined pressure & heat, holding the pressure / temperature for a set period of time, the steam extraction and finally the drying phase. An autoclave that runs a B class cycle is able to extract the air from hollow type A and B instruments through its vacuum process, an S class cycle is unable to do this.

If there is any doubt then you are better off purchasing an autoclave that will run a B class cycle for you as it will be able to sterilise any of the above instruments. Purchasing this type of autoclave also insures you against any change in your procedures or any potential change in the standard or regulation that you are meeting.

For free advice in respect of autoclaves, validation or servicing please do feel free to get in touch.

Phillip Lewis / [email protected]