Traceable Reference Materials: ISO 17025 or ISO 17034 - Which One Do I Need?

ISO17034 and ISO17025 are international standards used to prove traceability in measurement, testing, and calibrations.

ISO17034 - General requirements for the competence of reference material producers

This standard is related to the production of reference materials used in the measurement process, including validation, calibration, and quality control.

BIPM defines them as:

material, sufficiently homogeneous and stable with reference to specified properties, which has been established to be fit for its intended use in measurement or in examination of nominal properties.

Such materials are used for varied purposes, calibration of gas measurement devices being one.

Other types of reference materials include:

• fish tissue containing a stated mass fraction of a dioxin
• colour chart indicating one or more specified colours
• DNA compound containing a specified nucleotide sequence

ISO17025 - General requirements for the competence of testing and calibration laboratories

This standard is specific as it defines requirements for measurements in testing and calibrations.

BIPM defines calibration as:

an operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.

While these standards are in many ways related, they exist for different purposes. Key to both standards is traceability in all measurements and calibrations, and this is well defined elsewhere.

Why ISO17025, not ISO17034?

Different accreditation bodies around the world may choose to accredit a single activity in different ways. CAC GAS chooses to supply calibration gases accredited under ISO17025. This is not because we believe that ISO17034 is inferior, but because ISO17025 is more suitable for our purposes.

In the field of gas metrology, the preparation of calibration gases is well defined through various gas laws and physical principles. Gas mixture preparation can easily be described mathematically, hence it is straight-forward to prepare a calibration gas with a well-defined value and uncertainty.  The mixture produced has the same matrix as the mixture to be measured and can easily be analysed. ISO17025 was written to cover laboratories making these types of well-defined physical measurements.

In other areas of chemical metrology where ISO17034 is more applicable, it is more difficult to produce the Reference Material due to the chemical complexity and because there are many more variables and ill-defined matrix. ISO17034 gives producers of these more chemically based Reference Materials strict guidelines to follow which cover the production of all types of reference materials.

ISO17025 and ISO17034 both require the producer of the calibration gases and Reference Materials to have a robust quality system, undergo annual audits by the accreditation body, a technical expert for each method, and to participate in Proficiency Testing Schemes. The accreditation body ensures that all measurements are traceable, and the uncertainty budget claimed by the producer is a true reflection of the producer’s capability.  

CAC GAS supplies precision gravimetric calibration gases and high purity specialty gas mixtures for all applications where precision and accuracy are required. When you select CAC GAS for your specialty gases and equipment you will receive gases that offer the highest level of purity, consistency, compliance and accreditation.