Traceability improves quality control systems and reduces risk.  Within a laboratory setting, it is critical that all results are not only reliable but that they meet the industry standards.  Traceability connects to calibration and the ISO/IEC 17025 requirements.  Here is a guide to understanding how important traceability is.

The Definition of Traceability

In the science of measurement, it defines traceability as the “property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement of uncertainty”.

Traceability allowed the accuracy of measurement results to be established.  Measurement accuracy is an essential part of quality control.  Therefore, standards for weights and measures are maintained by a National Measurement Institute.

Traceability Standards

A reference standard material without a trail of traceability is of little value.  So defining traceability of laboratory standards is an important requirement of ISO/IEC 17025.

It is the property of the result of a measurement of the value of a standard whereby it can be related to stated references, expressed in SI units, through an unbroken chain of calibration comparisons, all having defined certainties.  A standard is universally accepted if other laboratories agree to adopt it as a reference for tests and measurements.

In case it is not possible to establish the chain of traceability of standards within a laboratory, then the standards can be sent for calibration at defined intervals.  An accredited calibration laboratory and calibration results along with the specified uncertainty values should be obtained along with the report specifying traceability to internationally acceptable standards.

How is Measurement Traceability Used?

Traceability is used to measure items that need a greater level of accuracy than normal.  This could be anything from a four-to-one greater accuracy right up to a 10-to-one greater accuracy.  They usually measure these to a national standard, as advised by the National Institute of Standards and Technology (NIST).

Traceability can be used to measure and calibrate all sorts of measuring equipment and instruments.  In industries where tools and apparatus are measured, a standard of at least four-to-one greater accuracy is recommended.

Depending on the industry and items to measure, it is possible that you may be required to show traceability to two standards.

When Can You Claim that Your Measurement is Traceable

We must do all the calibrations at regular intervals.  It is not enough that you once had your reference standard calibrated and then you continue to use it without recalibrations over years.  The calibration of any measurement device only remains valid for a stated period of time.  Therefore, the traceability expires when the calibration expired.

Every calibration needs documentation.  This means that the calibration results are documented in the calibration certificate.  It also important that they follow the calibration steps according to a written procedure within the company’s quality system.  Calibration without a certificate is specifically not a traceable calibration.  It is also important to realize that if they do the calibration without documented procedures, the calibration is not reliable.  Therefore, cannot be proven traceable.

Every step needs to include measurement uncertainty.  If the uncertainty information is missing from the calibration, you can not claim it is traceable.  The main reason is that without knowing and documenting the uncertainty, you could calibrate accurate measurement equipment with one that is less accurate.  Another issue could be that the calibration procedure causes such a big uncertainty that the calibration is neither good or traceable.

Accredited Calibrations

To get traceability in your lab, send your reference standard to an accredited calibration laboratory.  With an accredited laboratory, you know that competent auditors have evaluated the laboratory ensuring that everything is in the correct order.  At SRP control systems, we can help you with traceability and calibrations.  We have been working in the industry for over 40 years and can help your lab run efficiently.