Why does air need to be removed during steam sterilisation?

During steam sterilisation, trapped air can become a problem – because where there is air, the steam cannot act reliably.

For sterilisation to work reliably, saturated steam must reach all surfaces of the items being sterilised and transfer the required temperature evenly.

If air remains within the items being sterilised, it can hinder contact between the steam and the surface. This can lead to so-called cold spots – areas where the required sterilisation temperature is not reached, or is not reached reliably.

Where can air become trapped?

Trapped air is particularly problematic in materials and items to be sterilised from which it is difficult to expel the air. These include, in particular:

• Tubes and hollow bodies
• Bags and containers
• Packaging
• Textiles
• Porous materials

In these materials, it is difficult for the incoming steam to displace the air. In the case of hollow objects, for example, air may remain inside a tube. In textiles and porous materials, air can become trapped between the individual fibres or within the pores.

Why is trapped air problematic?

Trapped air can hinder contact between the steam and the surface of the items being sterilised. As a result, the steam cannot reliably reach all areas.

This can result in the required sterilisation temperature not being reached, or not being maintained for a sufficient duration, in certain areas. Such areas are referred to as cold spots and can jeopardise the success of the sterilisation process.

Why is the pre-vacuum important?

A pre-vacuum helps to ensure the reliable removal of air from the sterilisation chamber and, in particular, from hard-to-reach areas of the items being sterilised.

This allows the steam to penetrate more effectively into cavities, packaging and porous materials. This helps to ensure that the steam reaches the items to be sterilised as completely as possible.

This ensures that the required sterilisation conditions are maintained even in critical areas.

What is crucial for safe steam sterilisation?

The crucial point is the complete and reliable removal of air. Only when the steam can reach all relevant areas of the items to be sterilised can the required sterilisation conditions be reliably achieved.

In short

Where there is air, there cannot be steam. Where there is no steam, sterilisation may be compromised.

That is why the reliable removal of air is an essential prerequisite for safe steam sterilisation.