Measurement traceability
All equipment used for tests/calibrations, including those for subsidiary measurements having effect for the validity of the results, shall be calibrated prior to use. The laboratory shall have an established programme and a procedure for equipment calibration.
Traceability of the measurement standards and measuring instruments to the International System of Units (SI) is established by means of an unbroken chain of calibrations or comparisons linking them to relevant primary standards of the SI units of measurements.
When using external calibration services, traceability of the results shall be assured by the use of calibration services from laboratories that can demonstrate competence, measurement capability and traceability.
Calibrations that can not be made strictly in SI units shall provide confidence in measurements by establishing traceability to appropriate measurement standards (certified reference materials, specified methods or standards)