Dear Sir,

In EN285 the calibration of the thermometric recording instrument is described as:
26.4.9. The instrument shall be calibrated in accordance with the manufacturer's instructions and calibration shall include a temperature within the sterilization temperature band.

So if I calibrate at 121 °C and 125 °C (a two point calibration), is this then allowed for a validation of a sterilization cycle at 121 °C? If not, how can I preform a two point calibration of my thermometric recording instrument and still comply.

With kind regards,

Ronald Slob
Validation expert.

Hi Ronald,

The calibration should be performed at 3 temperature - 1high, 1 low and 1 target temp.

A two-point calibration is not suffiecient as you will not get linearity.

I suggest using 0.00, 140.00 and 121.00 for your temperature checks and -1, 1 and 3 bar (if using pressure). Remember the reference equipment you use must be at least three times (EN285 and HTM2010) more accurate than your recorder and your source must have a stability of less than 0.05'C.

Hope this helps.

If you need any more info, let me know.

Gary Philp
Validation Manager
C&M Scientific Ltd
Livingston, Scotland