Thermocouples in autoclave chamber during mfg loads

Does anyone know if its acceptable to leave thermocouples aside in the autoclave during manufacturing loads.

the reason i ask is that, for validation studies a lot of time is being lost due to locking out of utilities , leak tests , permits raised etc to constantly insert/ remove thermocouples between manufacturing loads.

any justification to leave them in would be great


Hi Neil

It would depend on the type of thermocouple that is being used. If it is a type T with bare ends then water ingress will quickly cause damage to the probe and so impact on accuracy. It is possible to buy proprietary cables that are sealed at the end in which case this problem is avoided. An alternative would be to consider using a wireless system which could be either a memory based system where you get the data out at the end of a cycle or a real-time transmitting system. The big advantage of the latter is that you have the real-time benefits of the cable based system you currently have without the time losses that you mention due to leak tests, locking utilities etc.

I absolutely agree with Geoff.

We purchased a wireless system last year. Though the ROI would have been 3 years for our projected use, we will break even this year. The wireless system has afforded us the flexibility to combine two data collection systems into one, run a lot more development studies, run studies on our schedule with minimal impact on production, and has generally saved us lots of frustration, time, and manpower. The amazing thing is the ability to see real time data in an autoclave about 9 feet deep or the ability to validate an SIP system spread throughout separate rooms!

That being said, we have left thermocouples which have sealed tips in a production autoclave knowing that we will again run a study very soon (e.g. later in the day). The justification is risk based. After the final study is completed and the thermocouples removed and during post-verification, what is the risk of one or more thermocouples are bad – tips/wire damaged or drifted out of acceptable range? Oh, and what is the risk that production personnel may damage or destroy thermocouples?

My opinion is to take out TCs because there is great chance to cut them off with trolleys or to have some other damage. in every case, if they put load the configuration and thermocouple position would not be the same so there are no need to stay in the chamber. And if the water penetrate and you have fail tc verification than you will not know when it happened and why? I know that it is much effort but its better to take out. And what if leak test fail with load inside… there are a lot of risk…

As per me, it is better to not put the thermocouples during the manufacturing load. Following are the risk involved.

  1. There is a possibility of leakage from the port.
  2. The thermocouple may cut due to trolley or items.

It is better to take separate load for the validation cycle. For the cost of utility, the quality and integrity cannot be challenged.

I will not leave the TCs - irrespective of their type - inside the chamber. Period. Why? Because the risk - however minute it might be - to the manufacturing load or equipment from contamination - will be HUGE and is not worth the amount of time saved.