National Standard for the Composition of Selected Gas Mixtures

National Standard for the Composition of Selected Gas Mixtures

The composition of gas mixtures is expressed as the amount fraction in the gaseous phase, which represents the ratio of the amount of substance of a component to the total amount of substance in the gas mixture.

Significance of Gas Composition Metrology

Metrology in this field plays a crucial role in the national economy, as there is a continuous need to determine the concentration of gaseous components in various sectors, including:

• Energy industry,
• Air quality monitoring,
• Measurement of gaseous emissions,
• Forensic investigations (such as determining blood alcohol content in breath analysis).

National Standard for the Composition of Selected Gas Mixtures

The National Standard for Gas Mixtures is traceable to mass, one of the fundamental SI units.

Core Components of the National Standard

The standard setup consists of:

• A maintained set of primary reference gas mixtures stored in 5 L pressure vessels with an internally treated surface,
• Filling equipment with a turbomolecular pump, vacuum, and pressure measurement instruments,
• Vacuuming system for pressure vessels with a turbomolecular pump,
• Automatic weighing system for 5 L pressure vessels with built-in comparator balances (resolution 1 mg),
• Analytical balances with 0.01 mg resolution,
• FTIR spectrometer with 10m and 100m gas cells,
• Gas chromatographs (GC) and GC-MS,
• NDIR analyzers for measuring ethanol and CO content in gas,
• Fluorescence analyzer for SO₂ content,
• Chemiluminescence analyzer for NOx content,
• Gas mixture homogenizer,
• Automated breath analyzer verification system,
• Gas distribution system,
• Autosampler devices,
• High-purity air generator,
• Instruments for recording temperature, pressure, and humidity.

Transfer of the Unit for the Amount Fraction in the Gaseous Phase

The primary medium for transferring the unit for the amount fraction in gas mixtures is certified reference materials (CRM) of gas mixtures. The transfer from PRM (Primary Reference Material) to lower-level CRM is performed using comparative chemical methods, including:

• Gas chromatography,
• Gas analyzers,
• FTIR spectrometry.

Certified Reference Materials (CRM) can be used for:

• Direct measurement of gas mixture components,
• Ongoing monitoring and validation of analytical procedures.

This standard ensures high-precision gas composition analysis, supporting industrial, environmental, and forensic applications.

Documents for download

• Osvedčenie (certifikát) (pdf, 917.4 kB)