I have a problem with my terminal autoclave. It sometimes raise temparature higher than the setting temperature such as 125 c (setting= 122)
Sounds like you have a ‘cold’ spot. Did you perform a temperature mapping and loading configuration study of the autoclave?
Wow. Terminal sterilization typically has a very tight uniformity requirements. Uniformity should be able to meet +/- 0.5 C from the mean (so +/- 1.0 overall).
Did you find this during empty chamber testing, during qualification, or some other time? Is this a liquid load, or a dry load?
Where was the high temperature location? What is the pressure of the steam coming in? You absolutely do not want superheated steam (which may be a possibility here). This would mean that your steam isn’t “wet” and you have dry heat kill, which is much less effective and undermines your process. That is why uniformity is such an important parameter for autoclave validation.
Rereading your post. If the whole autoclave raises above the set-point, you might simply have a control issue with the autoclave. This might require tuning the control points or some other activity to keep the autoclave controlling around the set-point. But please check the pressure/temperature of the incoming steam line.
Actually, when we perform sterilizer validation all criteria was meet requirement such chamber uniformity in distribution and penetration study. But I have the problem in few lot that temperature was raised 2 or 3 degree form setting so I must justify that cycle. On the validation, i had only validated chamber uniformity, microbial challenge and machine qualification. An maximum temperature which is not effect to product degradtion, does not performed. So How to determine it? or How do i justify a deviated cycle.
If I understand. You validated a cycle for uniformity, but then had to change a cycle to get higher temperature? Is that correct?
When autoclave a pharmaceutical product, I concern two important thing. The first one is sterility of product and the second is stability of product. For sterility of product, I could assure it by sterilizer validation based on practical guideline *but I do not know how to detemine the maximum temperature that does not effect to stability of product.* This is mypoint. So if you do not know the limit of temperature that affect product, you could not justified some of deviated cycle which high temperature. Is it has any pactical guideline for stability of terminal sterilization product?
I’m not aware of a guideline for how much overtemperature your product can experience before it deteriorates. I only know that guidelines state that you must control the uniformity of the autoclave, so that you don’t overprocess/overexpose the product.
I think it is left up the manufacturer to know what the limits are before there is some breakdown, or (without that knowledge), made a good engineering control so that there is little/no overprocessing (based on uniformity), just to be safe.
When you do autoclave validation, the minimum load is often done to support and defend that overprocessing does not happen. If there is overprocessing, it can happen during a minimum load (because a minimum load is expected to heat up faster and also potential get hotter).