Steam Quality Test Points

In order to test the steam quality specific test points on the steam line are required.

Fig 1 illustrates the location of the three test points on the steam supply pipe just prior to the sterilizer. This test point is usually installed between the steam main supply isolating valve and the sterilizer.

While not stated in either HTM 2010 or EN 285, there is an assumption that the steam sample point will be located as shown in Figure 1 above. This indicates that the sample pressure will be 3 – 4 Bar Gauge and that after the sample point there will be a steam separator and reduction stage prior to the sterilizer, which will be operating at 2.2 Bar Gauge (134 degrees celsius).

The relevance of this assumption only applies to the superheat test. In this case it is assumed that if the measured superheat of steam reduced to atmospheric pressure is less than 25 degrees celsius above boiling point at local atmospheric pressure, then the superheat present in the chamber will be less than 5 degrees celsius, following a further 1 to 2 Bar pressure drop. It may be necessary to adjust the acceptance criteria to suit the actual pressure drop utilised.