Do Steam Properties Influence Sterilization Efficacy?

Do steam properties influence sterilization efficacy? The short answer? Yes.

Stephanie Wiseman

In a recent article posted to the Sterilization & Infection Control Blog, Dr. Mario Finkiel, PhD, discusses why the quality of the steam used to sterilize matters in the overall outcome.

Dr. Finkiel says there are two types of steam that are not "good" for sterilization:

  • Wet steam
  • Superheated steam

Wet steam
The issue with wet steam ("steam at saturation temperature containing more than 5 percent water") is that it doesn't have enough energy. According to Dr. Finkiel, it "lowers the heat transfer efficiency of steam, which will result in an inefficient sterilization procedure." This leads problems such as:

Clogged pores. Wet steam congests packed loads and prevents the steam from penetrating the sealed pouch.
Humidity. A "wet load" creates a humid environment which may allow bacteria to thrive.
Corrosion. The wetness can cause corrosion or "spotting" on the device being sterilized.

Superheated steam
The issue with superheated steam ("when steam becomes too hot, compared to the steam table") is that the steam is too hot to condense. According to Dr. Finkiel, "An autoclave fed with superheated steam will function like a dry heat sterilizer, in which the killing of micro-organisms is less efficient than the optimal saturated steam required for sterilization." This leads to the problem of:

Time. Dr. Finkiel points out that "The dry heat sterilization process takes much longer even at higher temperatures than steam sterilization." Up to 30 minutes of exposure can be needed.
Do you ever think about the quality of the steam used to sterilize your device packaging? Have you encountered either (or both) of these issues before? How did you remedy the situation?

Focused on medical packaging design and technology?

Stephanie Wiseman, Community Editor, UBM

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