Steam Quality Testing

The week of September 4, 2017, Clarence Raiford a Senior Validation Engineer with Performance Validation conducted training on how to perform steam quality testing per HTM 2010, and EN 285 [available for purchase from various vendors].  The effectiveness of moist heat sterilization is dependent on three key quality parameters of the clean steam provided to the sterilizer:

  • Steam Non-Condensable gas test: The amount of the steam by volume that is not steam or water, but is air or other gas that does not contribute meaningfully to sterility of the load. If the non-condensable gasses exceed 3.5%, during sterilization the non-condensable gasses can surround the items to be sterilized and inhibit head penetration to the surface of the object and thus fail to meet sterility conditions.
  • Steam Superheat test: The temperature of the steam above the temperature of saturated steam for a given moisture content. Autoclaves/ sterilizers use moist heat i.e., saturated steam.  If the steam becomes superheated (superheat > 25°K) the steam will become too dry and will not achieve the desired sterility conditions.  The autoclave may behave as a dry heat sterilizer vs moist heat requiring a longer exposure time to achieve sterility conditions.
  • Steam Dryness test: The amount of the steam by weight that is steam and not liquid water. This test is important as the effectiveness of the sterilization is dependent on the quality of the steam.  The criteria for steam dryness is ≥ .90 (steam weight compared to water weight) or >.95 w/w if metal loads are processed and throughout the operating cycle, the steam measured in the steam service pipe is within 3°C of that measured in the same location during the superheat test. Steam dryness results outside of the acceptance criteria may result in wet loads (moisture evident in the chamber or on the load post sterilization) and may indicate that sterility conditions were not achieved.

HTM 2010 recommends that these tests be completed annually and during revalidation of the sterilizer.  Performance Validation has a number of personnel who are qualified to perform these tests.  Please use our contact form if you would like additional information or a quote to perform steam quality testing in your facility.