TST Dowie Dick test - 121ºc for up to 8.3 minutes

EN ISO 17665-1
requires that a steam penetration test be performed every day the autoclave is used.

A test conducted confirms that steam penetration occurs quickly and evenly and indicates that air and other non-condensable gases are effectively removed.
The indicator sheet in the center of the package shows a clear color change from yellow to dark blue/purple when exposed to a specific combination of time, temperature, and steam.

When there is no air or other non-condensable gases in the chamber, vapor can penetrate the package quickly and completely, and the indicator shows a uniform color change.
If air or other non-condensable gases are present, they will collect towards the center of the package, with an air/gas pocket preventing contact between the vapor and the indicator sheet. The temperature or humidity level (or both) is lower in the area of ​​the air/gas pocket, resulting in a non-uniform color change on the indicator.