Overview
EN ISO 16664:2017 - "Gas analysis - Handling of calibration gases and gas mixtures - Guidelines" (ISO 16664:2017) provides practical guidance on preserving the declared composition and uncertainty of calibration gases (pure gases and homogeneous gas mixtures) during their utilization period. Published by CEN/ISO, the standard focuses on factors that can change gas composition between delivery and use: storage, transport, withdrawal from cylinders, and transfer to the calibration point. It also outlines a method for stability assessment, linking the producer’s certificate uncertainty with the user’s measurement uncertainty.
Key topics and requirements
- Scope and definitions: clear terminology for calibration gas, stability, homogeneity, transfer system, measurement uncertainty and maximum storage life.
- Storage and transport: environmental influences (temperature extremes, moisture) and general precautions for cylinder storage to limit composition changes during the utilization period.
- Modes of withdrawal: recommendations affecting composition - minimum utilization pressure, temperature control, pressure reduction and flow management, and procedures for cylinder replacement or position changes.
- Transfer system design: guidance on purging procedures, leak tightness, materials selection and construction of gas-conducting lines that connect the cylinder valve to the measurement instrument.
- Sampling and flow considerations: modes of gas sampling and the effect of pressure/flow control devices on sample integrity (step response time and stability).
- Stability assessment method: an approach for users to check whether a gas mixture remains within certified limits, accounting for the certificate’s composition uncertainty and the user’s measurement uncertainty (see Annex A for a user check procedure).
Practical applications - who should use this standard
EN ISO 16664:2017 is relevant to organizations and professionals involved in:
- Gas producers and suppliers - to define handling and labeling practices and to set utilization periods.
- Calibration and metrology laboratories - to ensure traceable calibrations using cylinder gases.
- Environmental monitoring and emissions testing - where accurate gas calibration is critical for regulatory compliance.
- Industrial process control and safety monitoring - to maintain sensor and analyzer accuracy.
- Quality assurance and compliance teams - to demonstrate appropriate control of calibration standards.
Related standards
- ISO 7504 (terms and concepts for gas analysis)
- ISO 6142‑1 (gas mixtures - preparation and handling; reference to expiry/maximum storage life)
- ISO/IEC Guide 99 (GUM / measurement standards concepts)
Keywords: calibration gases, gas mixtures, gas analysis, calibration gas handling, cylinder storage, transfer system, stability assessment, measurement uncertainty.
