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CRM gas reference materials

CRM gas reference materials

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CRM gas reference materials

LAT Centre No. 143 can produce Certified Reference Gas Materials (CRM) as it is accredited according to UNI CEI EN ISO/IEC 17034:2017. For this type of mixture the Centre warrants and certifies a period of stability in which the homogeneity of the mixture and the correctness of the certified values are ensured.

This warranty is made possible thanks to the stability studies that the Centre has been conducting since 2004 on a very large group of mixtures representing the CRMs produced. The stability studiesdemonstrate the stability of the mixtures for over 7 years, i.e. much longer than that guaranteed for the customer. These studies are continuing and are integrated with the new types of mixtures that the Centre can produce.

The CRMs are produced gravimetrically according to the standard ISO 6142.

Metrological traceability derives from the mass samples calibrated by a Primary Metrological Institute or by an Accredited Centre used for gravimetric preparation of the mixtures.

The calculation of the concentration and the uncertainty of the final mixture takes into account: the choice and quality of the raw materials and the mother mixtures; the masses used for calibrating the balances and their performance; the calibration environmental conditions; the preparation procedure with all the uncertainties relating to the weighing process. All the individually prepared mixtures are analytically verified. The analysis follows the guidelines of ISO 6143, which provides a three-point instrumental calibration using the method of generalized least squares (GLS). The samples used for instrumental calibration are metrologically traceable mixtures produced by the Centre (G-CRM or CRM) or certified by a Primary Metrological Institute. The CRMs are characterized by the better preparation tolerance, defined as the difference between the requested value and the certified value, and by very small relative extended uncertainties.

The main recommended applications are:

  • the calibration of equipment requiring binding measurement performance with the best possible uncertainties available in the market (legislative parameters, specifications of supply, etc..). 

These samples are only available as binary mixtures because of the stability studies that have been carried out.

Certified gaseous reference materials