Paul Daniel

nov. 6, 2019
Hello,

Thanks for your comment. I’m sorry to hear of your difficulties! In my past work validating autoclaves, I have seen issues like this before. Despite being inexpensive and tolerant of high temperatures, thermocouples have high drift and that can often lead to a failed post-calibration. To counteract this, I used to write into the protocol document itself a clause that would allow a small percentage of the thermocouples to fail post-cal, yet allow the study to pass. That works well for empty chambers, but is not as robust for loaded chambers, as there may have only been one thermocouple in the affected piece of equipment (filer in this case). Another approach is to analyze the post-calibration failure itself. If we assume the failure was linear and in only one direction, then a thermocouple that appears to be registering lower than expected temperatures during post-calibration would likely have under-reported temperature values, and thus under reported the accumulated lethality. In which case, you might be able to convince QA that the measurements would only have provided an additional challenge. There is no guarantee, because this is based on the assumption that the calibration failure would be in one direction only. If the failed thermocouple was reading too hot, then this won’t work at all. Your best course of action might be to simply repeat the study.

Paul Daniel