Autoclave Qualification Acceptance Criteria

Is any one or two reading below 121 c is acceptable?like 120.6 or 120.8

The quick answer is no. The long answer is when/why did it happen? Was the temperature at the beginning when things were still ramping up or equilibrating? Also, what is your set point temperature?

To avoid the “failure” you might examine when in the cycle the failures happened, where in the cycle the failures happened (distribution probe, or a penetration/part probe).

Also, could this be due to pooling of water? If so, is the ramp rate slow enough, so that the items are up to temperature at the time the “soak” or “exposure” time is started. (A cool item might condense water initially, and the probe might lie in the water (which will be slightly cooler).

Dear Jared
Thanks for reply
This minor fluctuation was observed in both Heat distribution and heat penetration cycle. Set point is 121.1 and out of 20 thermocouple only one or two reading was observed below 121 during any time of 15 minute sterilization hold. Here are and post study calibration data was also fond is any guide line allow this type of minor jurk or fluctuation
in any single thermocouple?

E time is also found OK. This type of fluctuation was found only for ten to twenty second only in one thermocouple. Apart from this single reading other all data of that thermocouple was above 122 C and average of that thermocouple is also above 122 C. Temperature profile of other all 19 thermocouple is also above 121.9 C.FO value is also found above 15 for all thermocouple.


So your set point is 121.1? I understand your acceptance criteria is 121.1, but what is the autoclave actually targeting to control around? It shouldn’t be exactly 121.1; preferably there is some temperature above 121.1 that you can actually run at (without damaging the product in the autoclave). A common set point is 123, but please be sure that nothing will get damages at 123 C (not likely as 121.1 and 123 are pretty close is temp, but please be sure).

Here are two mentions of autoclave temperature in this forum, one mentions 123 and the other mentions 122.

Equipment is controlling at 121.5. Here I m not getting any rout cause for only single or two reading below 121 only in one thermocouple.

I would do a few things

1 - Raise the temperature to 122 set point (very common)
2 - See where the penetration temperature fluxuation is - it might be caused by temporary blockage caused by condensate pooling on the equipment. Orientation of the parts within the autoclave is a critical feature; do this to avoid pooling or condensation. Air will “settle” in parts similar to a liquid. If you think of air as a liquid, you want to orient the components so that the air “drains” out of the parts. So make sure your componenets are oriented so that air would easily drain out of them. Put sort bowls upside-down. Put graduated cylinders upside-down. Anything that could contain air, upside-down to drain the air out. However you orient the equipment during the validation, make sure you orient during normal use. You MUST ensure the equipment is oriented correctly every time (through training, and SOPs, and maybe a checklist form to ensure people have documented that they have oriented the equipment correctly).

3 - Regarding the fluctuation in the distribution probe. That is the most concerning. How old is the autoclave, what kind? Why is there a dip in distribution temperature. The distribution temperature really should be spot on. Is the jacket somehow cooling in one spot? Is the jacket somehow cooler overall? Again this is the most surprising. It if is early in the cycle, there are reasons for this. If it is in the middle of the cycle, then the control of the autoclave might be suspect.

I agree with you regarding temperature drop due to condensate accumulation in load but some time temperature drop observed in empty chamber study also for 10 to 20 second. All RTD sensor saw temperature above 122. Only minor jurk observed in single thermocouple. Equipment was not to much old. Jacket temp is also found OK.out of 16 thermocouple only one thermocouple saw fluctuation. Other all are within 0.3 C vernation during sterilization hold means controlling of equipment is also OK.

Where in the empty chamber? The drain? The floor, the wall? Your probes should b 1-2 inches away from the wall. I wouldn’t expect the wall to have much problem. Maybe the floor.

Is your autoclave sufficiently insulated? It might be that your autoclave isn’t in fact as uniform as you need it to be. Maybe near a port there is a cool spot.

Is the cool spot always a little cooler, or was it just a temporary dip in temperature.

Sorry, this is hard to do over a post forum, and without seeing all the possible variables.

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Is this sudden drop in temperature below 121.1 for 2 readings acceptable in case of steam in place sterilization of vessels