ISO 17025 & ISO 17034: Technical requirements for metrological gas mixtures

Metrological gas mixtures are essential to ensure reliable measurements in laboratories dedicated to analysis, quality control, and calibration.

Two international standards, ISO 17025 and ISO 17034, clearly define what makes a gas mixture suitable for metrological use.

Understanding these standards helps laboratories select the right supplier and use mixtures in compliance with the required quality standards. 

ISO 17025: requirements for traceable and comparable results 

ISO 17025 sets out the general requirements for the competence of testing and calibration laboratories. 

One of its key provisions is the obligation to use reference materials that are traceable to recognized standards, such as those of the International System of Units (SI).

In the context of metrological gas mixtures, this means: 

• Using certified mixtures whose values are linked to primary or secondary references.
• Always request a certificate detailing measurement uncertainty, stability data, preparation method, and traceability.
• Assessing the measurement uncertainties associated with certified values to ensure reliability and compliance in calibration processes.

The use of non-compliant mixtures can undermine calibration validity, raise audit findings, and compromise data reliability.

ISO 17025 therefore requires a rigorous documentation system directly linked to the characteristics of the mixtures employed.

ISO 17034: assurance of reference material quality

While ISO 17025 targets laboratories, ISO 17034 specifies the requirements for producers of Certified Reference Materials (CRM).

A supplier accredited under this standard must ensure: 

• Mixtures certified through a validated process.
• Independent checks on gas stability and homogeneity within the container.
• Technical documentation that includes certified values, uncertainties, measurement methods, validity period, and references to recognized international methods.

For the end user, this translates into more reliable data, reduced risk of disputes in case of non-conformity, and fewer additional checks on materials.

A laboratory working with gases produced under ISO 17034 can objectively demonstrate the quality of its measurements.

Choosing ISO-compliant gas mixtures

In practice, aligning with ISO 17025 and ISO 17034 requires strategic operational choices:

• Evaluate suppliers not only on price, but also on accreditation and documentation quality.
• Consistently store and archive certificates within the internal quality management system.
• Verify that the declared uncertainties of mixtures match the tolerances of the instruments in use.
• Align mixture replacement schedules with instrument maintenance protocols and calibration cycles.

Using ISO-compliant mixtures brings concrete advantages:

• Reduced risk of non-conformities and measurement errors.
• Higher data quality and reliability, thanks to traceable and stable materials with declared uncertainty.
• Demonstrable compliance with international standards, valuable for audit and accreditations.
• Greater efficiency in metrological management, with fewer additional verification requirements.

In short, these standards are not just “audit requirements” but operational tools that enable laboratories to work more safely, traceably, and efficiently.

Discover PERFECTA, SIAD’s dedicated metrology brand, providing gas mixtures fully compliant with ISO 17025 and ISO 17034.