Overview
EN ISO 6144:2006 (identical to ISO 6144:2003) defines a static volumetric method for preparing calibration gas mixtures used in gas analysis. The standard specifies how to prepare binary or multi-component calibration mixtures by injecting known volumes or masses of calibration components into a complementary (diluent) gas within a gas‑mixing chamber, and how to calculate the volume fraction of each component. It also requires a rigorous evaluation of the expanded uncertainty for each calibration component by accounting for all measurement uncertainties (apparatus and procedure).
Keywords: EN ISO 6144:2006, ISO 6144:2003, calibration gas mixtures, static volumetric method, gas analysis, volume fraction, uncertainty.
Key topics and requirements
- Scope and applicability
- Used for preparing calibration gas mixtures (binary or multi-component); typical concentration range noted as about 10 ppb to 50 ppm, although other ranges are possible with appropriate selection of components.
- Principle
- Injection of known volumes of gaseous or known masses/volumes of liquid calibration components into a diluent gas, homogenization, equilibration to ambient temperature, and pressurization to a measured above‑atmospheric pressure.
- Apparatus & components
- Gas‑mixing chamber / vessel (evacuable, inert materials, pressure rated)
- Vacuum pump, gas lines, pressure/vacuum/temperature gauges
- Septum and calibrated metering syringes (gastight, experimentally verified volume)
- Motor‑driven mixing device, pressure relief valve, outlet sampling line
- Apparatus for filling syringes and high‑pressure source cylinders
- Uncertainty evaluation
- Procedure to determine expanded uncertainty of the volume fraction, including contributions from apparatus calibration, residual gas, syringe volume, pressure/temperature measurement and experimental procedure.
- Notes indicate that a relative expanded uncertainty of ≤ ±1 % (95 % confidence) may be achievable under controlled conditions (documented purities, no adsorption/reactions, calibrated apparatus).
- Supporting material
- Informative annexes provide examples of apparatus, syringe volume determination, uncertainty calculations and stability tests.
Applications and users
- Applications
- Preparation of calibration gases for ambient air and industrial gas analyzers, instrument calibration, proficiency testing, and laboratory traceability chains.
- Who uses it
- Gas analysis laboratories, calibration service providers, environmental monitoring agencies, instrument manufacturers, quality managers and metrology institutes involved in gas calibration and standard gas production.
Related standards
- Normative reference: ISO 7504 (Gas analysis - Vocabulary) is cited for terms and definitions.
- Users should consider complementary metrology and gas‑analysis standards when implementing calibration and uncertainty practices.
