Revalidation of an autoclave typically requires 12 temperature probes strategically distributed
throughout the chamber to ensure uniform sterilization.
Key probe placements include:
- Near the door
- At the corners
- In the center of the load
- Close to critical areas, such as larger mass or denser materials
- Near the drain
This helps confirm that the autoclave consistently reaches and holds the required sterilization
temperature. While the exact number of probes can vary depending on the autoclave size and
validation protocol, data loggers are commonly used to record temperature at these various
points. These loggers often have multiple channels to capture data from the probes.
Although many regulatory guidelines provide general instructions on autoclave validation,
most do not specify the exact number of probes or thermocouples.
𝐅𝐨𝐫 𝐞𝐱𝐚𝐦𝐩𝐥𝐞:
PDA Technical Report 1 suggests using a minimum of 10 thermocouples, or 5 per 100 cubic
feet for larger autoclaves. However, it does not define what constitutes a “large” autoclave.
HTM 2010 Part 3 (Sterilization: Validation and Verification) requires 12 thermocouples,
along with one pressure sensor, to validate both temperature and pressure.
The thermocouple should not be touched to the wall of the autoclave because walls will have
higher temperature than the chamber.