17:00 Aug 8, 2011 

this term is used quite often, that's why I used it. I mean, in a part which was already translated. I think I'll keep it. Thanks for the help you brought on this

16:47 Aug 8, 2011 

Whether or not you need to / should add 'essais' really depends on the rest of your context — what is this mystery substance / equipment, and is it the actual thing that is going to be tested, or simply used for testing other things? I think I'd tend to steer clear and stick to something more non-committal like 'utilisation'.

16:35 Aug 8, 2011 

since you two seem to agree on that point. Do you think something like "Pour essais en laboratoire uniquement" would fit here?

16:17 Aug 8, 2011 

I believe that the English is poorly written and that the adjective "non-consumer" applies to the noun "purposes" rather than the noun "laboratory", as Tony also says. The addition of a comma might help:
For non-consumer, laboratory purposes only
[i.e. For non-consumer purposes only and for laboratory purposes only]

16:10 Aug 8, 2011 

Yes, absolutely, it is 'for laboratory purposes only' instead of 'for consumer use' — parsing it as 'non-consumer laboratory' seems to be leading to confusion.

16:07 Aug 8, 2011 

and I find your formulation really interesting. It fits well in the context. Many thanks

15:34 Aug 8, 2011 

so, in my understanding, if this is not commercial, it is intended to professional laboratories only, doesn't it ?

14:59 Aug 8, 2011 

I do not understand this to refer to some sort of distinction between a private and a public laboratory, but to products that are not for commercial use, i.e. "for non-consumer laboratory purposes only" = not for consumer [or commercial] purposes/use/sale, but for laboratory [testing] purposes only. Something along the lines of "Non destiné à la vente ou à l’utilisation par le public. À l'usage du/pour utilisation en laboratoire seulement". See here, e.g.: Packaging - It is essential that the monitor test piece be clearly distinguishable from commercial cigarettes.
FOR NON-CONSUMER LABORATORY TESTING PURPOSES ONLY
NON-COMMERCIAL PRODUCT
DATE OF PRODUCTION: XXXXX
http://www.coresta.fr/Guides/Guide-No8-Monitor-Production_Ap...