Our Engineers provide Steam Quality Testing, Troubleshooting and remediation plans where required. This ranges from routine Steam Quality Testing at all steam user points to system troubleshooting and design improvements. Through our relationship with De Lama we can also provide Steam Generators ( Clean, Pure and Ultra Pure Pyrogen Free).

The physical properties of steam used for equipment sterilisation and SIP are critical. The requirements for steam quality testing have long been defined in many national and international standards:

  • HTM01
  • HTM2031
  • EN 285
  • AAMI ST79
  • PDA TR1
  • ISO 17665

The physical properties of steam requiring measurement and control are described below.

Non Condensable Gases

Non condensable gases can be present in the steam supply either because of failures at the steam generation stage or poor distribution system design failing to remove air from the system following shutdowns.

Whatever the cause, the presence of non condensable gases in the sterilisation processes can result in an area of the equipment being insulated from full moist heat conditions. Microbiology can take significantly longer to kill in dry heat rather than moist heat and therefore this is a variable that must be controlled.

Non condensable gases ≤3.5%         

(NCG to condensate %)

Dryness Value

The dryness value or dryness fraction is a measure of the amount of energy in the steam. The latent heat energy required to complete the phase change from liquid water to water vapour is significant.

The higher the energy of the steam that is introduced to the sterilisation process the less steam will be required to heat up the equipment to be sterilised, therefore less condensate will be made (less steam = less condensate formed). If less condensate is made then it is more likely the load can be removed dry.

Dry equipment loads following porous load sterilisation are essential as a wet load is much more easily recontaminated than a dry load. Wet loads should be rejected.

Dryness Value  ≥ 0.95             

(Greater than 95% latent heat energy)

Wet steam (low dryness value) is generally a consequence of the steam distribution system design / installation. Factors such as:-

  • Line slopes / direction of slopes.
  • Steam trap specification and installation.
  • Steam velocity / system design
  • Steam separators installation
  • Lagging and routine operation / shutdown.

There are many other possible causes of wet loads but steam dryness is certainly one of them.


A measurement required by the standards but rarely if ever a problem. The potential problem with superheated steam entering the autoclave chamber is that dry heat conditions could be established (slow microbial kill) and also poor temperature distribution throughout the chamber / load.

Superheat                   ≤ 25oC

Our Engineers provide contract steam quality testing services using industry standard test equipment in compliance with EN285 and HTM01. The methods can be adopted to suit your application and your internal standards / requirements which will be discussed at time of contract.