The following question was posted in the forum last week in relation to thermocouples and it sparked a lot of debate around the use of thermocouples in manufacturing loads. All opinions are welcome, please leave your comment at the end of this article.

Thermocouple Leave In or Leave Out?

“Does anyone know if it’s 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”

Posted By: griffinneil

What Type of Thermocouple is Used?

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.

Posted by: Geoff Shaw

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Wireless Thermocouples

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 during post-verification, what is the risk of one or more thermocouples getting affected – tips/wire damaged or drifted out of acceptable range? Oh, and what is the risk that production personnel may damage or destroy thermocouples?

Posted by: Neerav

Take Out the Thermocouples

My opinion is to take out the thermocouples because there is a good chance to cut them off with trolleys or allow some other kind of damage to happen. If the load configuration and thermocouple position are the same there is no need for them to stay in the chamber and if the water penetrates you will not know when it happened and why?

I know that it is a lot of effort to remove them each time but I think to avoid such problems this would be a good idea.

And what if the leak test fails again more risk!

Posted by: joksavs