Traceability of Calibration Standards and Role of National Metrology Laboratories

Traceability of Calibration Standards and Role of National Metrology Laboratories
Calibrate against Certified Reference Materials

Significance of instrument calibration on quality of results discusses the importance of standards with established traceability. Let us first of all understand meaning of traceability.

Traceability refers to a process that ensures all equipment and test procedures are calibrated using standards procured directly from recognized international standardization bodies or at least an unbroken chain of comparisons can be established between the standard and the standardization body. In other words the calibration results within acceptable limits of uncertainty obtained by you should be compatible with similar results obtained by any other laboratory under the same controlled experimental conditions.

Certified Reference Materials

Certified Reference Materials should be used to validate methods and measurement systems as per specified procedures. These are universally accepted as they are traceable to internationally recognized standardization bodies.

Basic responsibilities of calibration laboratories

In compliance with the requirements of ISO 17025:2005 a calibration laboratory should maintain certified reference materials, standard weights and measurement standards having established traceability. In addition the following conditions are required to be fulfilled:

  • Specified environmental controls should be maintained to carry out calibrations
  • Only competent and skilled persons should be responsible for carrying out calibration activities. Training skills of such persons should be upgraded from time to time
  • Calibration results should be reported within acceptable limits of uncertainty

Role of National Metrology Laboratories

National metrology laboratories play a significant role in upkeep of standards and quality of manufactured goods. Other laboratories can rely upon them for their standardization, certification and training requirements.

Each country should have its own national metrology laboratory which should provide guidance and services to other laboratories in compliance with ISO 17025:2005 requirements. It should maintain national standards and under the prescribed conditions. Such standards should be traceable to international standardization bodies.

Some countries do not have their own national metrology laboratories. Smaller laboratories of such countries can seek alliance and guidance for calibration purposes with the national metrology laboratories in their neighbouring countries. Ideally on-site calibration should be contracted because it is cumbersome to transfer sophisticated and bulky systems and calibration also becomes invalid due to transfer and re-installation at different locations sites.

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