Symbol for temperature limit

[shimonv]

Hi Fellows,
I've seen many device labels with a temperature limit symbol that has upper and lower values; same thing regarding the humidity limitation symbol.
What I did not see is a study that validates the entire range.
What I usually see is a shelf-life study with desired real-time and accelerated temperature but this doesn't constitute a validation for temperature or humidity range.

What is your experience?

Thanks,
Shimon

 

[Ronen E]

My experience in general is that industry tends to handle the entire subject of temperature sensitivity (including shelf life) in a pseudo-engineering (sometimes bordering irrational) manner, so pretty much anything goes as long as it can be "sold" to auditors. The obvious exceptions are cases where a device has a very explicit temperature sensitivity which is pivotal to it's function. But as far as general product sensitivity is concerned, manufacturers tend to treat this as a headache or a box that needs ticking off at the lowest possible resources (thinking, time, money) investment.

I've written about it here many times, it's one of my pet peeves.

 

[shimonv]

Thank Ronen. It is mind boggling.
Fortunately, most medical devices are not sensitive to the environment to the extent that you need to validate a range of storage conditions. Shipping conditions is relatively easy to do. I shall say no more.
Shimon

 

[Jean_B]

My experience in general is that industry tends to handle the entire subject of temperature sensitivity (including shelf life) in a pseudo-engineering (sometimes bordering irrational) manner, so pretty much anything goes as long as it can be "sold" to auditors. The obvious exceptions are cases where a device has a very explicit temperature sensitivity which is pivotal to it's function. But as far as general product sensitivity is concerned, manufacturers tend to treat this a a headache or a box that needs ticking off at the lowest possible resources (thinking, time, money) investment.

I've written about it here many times, it's one of my pet peeves.

Jumping in because it is an interesting topic, what kind of resources (training, literature, cases) do you recommend to get someone started on getting wise on the general aspects to take into account, or even details. E.g. temperature limits during transport can depend on means of transport, but what kind of environment (humidity, temperature, pressures) is agreed to be typical to take into account in for example aircraft cargo holds?

 

[Ronen E]

what kind of resources (training, literature, cases) do you recommend to get someone started on getting wise on the general aspects to take into account

I had never put together an orderly training program on this (no one seems interested in listening), so I never bothered to prepare an orderly collection of resources. I once gave a talk about this topic in 2007 (I think) but I'm not sure I have the slides or notes any more.
If you care to find what I think, just search Elsmar for my posts containing the terms "temperature", "accelerated ageing" etc.
Other than that, Google is your friend. I would suggest beginning with gaining a very good understanding of the Arrhenius equation and what it actually stands for, then understanding the simplified Q10 model and its limitations. Then maybe just look for some articles (Google Scholar?) related to environmental stresses and related product testing.

what kind of environment (humidity, temperature, pressures) is agreed to be typical to take into account in for example aircraft cargo holds?

I'm not aware of a wide agreement on what's considered typical, and besides, looking for "typical" goes against what I argue for - namely, really understanding what's going on inside your own product, and how it's affected by the specific conditions your own product is exposed to.
If you don't believe in research you'd probably end up with GIGO. "Research" might sound scary but in this context it's nothing more than a careful collection of relevant and reliable information.

 

[Jean_B]

So the start for finding out your own exposure conditions would be sending a monitoring device (or several in the right spots) with representative product (be it prototype, predicate etc), and then applying the measured profile (i.e. envelop of conditions versus time spent in travel) into the research on how your product would be affected? Then it could be said that, unlike the ISTA 2a schedules and assorted standards on environmental stresses for storage in specific climates, there are no such guidelines for transport. Made even iffier in cases where the words 'only an excursion' are used.

 

[Ronen E]

Generally, yes. There might be some ways around actually collecting raw data with loggers etc., depending on criticallity (needs science-based justification and valid information substitutes). The key is to approach it in a rational manner with no preconceived (and worse, unstated) assumptions.

ISTA guidelines are for packaging, essentially.