EN ISO 6145-5:2010 PDF

Overview

EN ISO 6145-5:2010 (ISO 6145-5:2009) defines the use of capillary calibration devices and gas dividers for the continuous, dynamic volumetric preparation of calibration gas mixtures. The standard specifies principles, apparatus, procedures, verification and uncertainty considerations for producing traceable gas mixtures from pure gases or pre-prepared mixtures using single or multiple capillaries.

Key topics and requirements

• Scope and principle
  • Continuous production of calibration gases by adding a constant capillary flow to a controlled complementary gas flow.
  • Single capillary systems cover minor component volume fractions from approximately 10⁻⁸ to 0.5.
  • Gas dividers perform controlled volumetric dilution over ranges from 0.0005 to 0.9 of the primary gas concentration.
• Performance and uncertainty
  • Typical relative expanded uncertainty: less than ±2 % (k = 2) for the technique.
  • Gas divider repeatability: better than 0.5 %.
• Apparatus and setup
  • Typical components: capillaries, two-stage pressure regulators with fine adjustment valves, differential manometers, mixing manifold, gas filters and optional thermostatic control.
  • Thermostatic control (e.g., water-jacket to ±1 °C) is recommended for high accuracy because temperature affects gas viscosity and flow; it limits final mixture variation to within about ±2 %.
• Calibration and calculations
  • Flow through capillaries follows a pressure-drop relation; individual capillaries are characterized by a calibration factor (K) obtained by measuring flow vs differential pressure.
  • Verification and uncertainty estimation procedures are described; Annex A gives a numerical example and Annex B provides uncertainty derivation.

Applications and users

• Practical uses:
  • Production of certification and calibration gases for analytical instruments (GC, FTIR, mass spectrometers).
  • Industrial gas mixing panels and controlled-atmosphere generation.
  • Generating low-level reference mixtures for environmental and trace gas analysis.
• Primary users:
  • Metrology and calibration laboratories, gas manufacturers and suppliers, instrument manufacturers, quality assurance teams, and research labs requiring traceable calibration standards.

Traceability and verification

• Traceability is achieved by comparison with mixtures related to national or international gas standards (example procedure in Annex A).
• The standard describes verification steps, flow determination and uncertainty sources (temperature, viscosity, pressure, and capillary geometry).

Related standards

• ISO 6145 series (dynamic volumetric methods): Part 1 (methods of calibration), Part 2 (volumetric pumps), Part 4 (syringe injection), Part 6 (critical orifices), Part 7 (thermal mass-flow controllers), Part 8–11 (diffusion, saturation, permeation, electrochemical generation).
• ISO 6143 (comparison methods for checking composition of calibration gas mixtures).

Keywords: EN ISO 6145-5, capillary calibration devices, gas dividers, calibration gas mixtures, dynamic volumetric methods, traceability, uncertainty.