Glassware calibration

[Fabiano]

Dear All,

Is anyone working under 17025 doing regular verification of calibrated glassware?
Is there in European or US rules, correction for the air buoyancy effect or atmosferic pressure, or just the density of water according to temperature?

Thanks
Fabiano

[MikeD]

This link may be useful http://www.npl.co.uk/mass/faqs/buoyancy.html but in my opinion buoyancy/air pressure corrections are only significant when comparing primary weights to the smallest possible uncertainty. Yes the effects are measurable but are you concerned about maximum bias effects around 0.09 % in volume (of water) ? It depends on your objective. It's about the same as a 2 deg C difference in water temperature.

Neverthess your 17025 accreditation body may like to see that you are at least capable of calculating the magnitude of buoyancy correction, then deciding on the significance (eg. negligible) for your uncertainty. If you then discount it the AB should be satisfied with that. On the other hand it's no big deal to include small corrections in a spreadsheet.

[k66]

Dear All,

Is anyone working under 17025 doing regular verification of calibrated glassware?

I do.
It's one big stupidity! When you buy glass A+ from ex. Duran ... do you have conditions so well as in Duran laboratory? Probably not... so it make no sense. But GMP - yes yes ... generate more paper