ISO 2612:2023

Overview

ISO 2612:2023 specifies test methods for measuring trace levels of ammonia (NH3) in natural gas and biomethane using tuneable diode laser absorption spectroscopy (TDLAS). The standard covers safe handling and sampling of pressurised ammonia/methane mixtures, calibration and measurement strategies, and practical implementation using commercially available spectroscopic NH3 analysers (treated as a black box). It targets quantification around and above 10 mg·m‑3 (≈14 µmol·mol‑1) and applies for absolute pressures 1–2 bar, temperatures 0 °C–40 °C, and relative humidity < 90%.

Key topics and technical requirements

• Measurand and matrix: Amount fraction of NH3 in a methane/biomethane matrix.
• Measurement technique: Tuneable diode laser absorption spectroscopy (TDLAS) using commercial NH3 analysers.
• Apparatus and sensors:
  • NH3 analyser (commercial spectroscopic unit)
  • Gas delivery system, temperature and pressure sensors
  • Calibration equipment: pressure regulators, flow controllers/meters, dilution devices, output manifolds
• Sampling and handling: Construction materials, cleanliness, installation of calibration gas cylinders, purging of valves/lines, flow and leak control to reduce adsorption (“stickiness”) and contamination.
• Calibration strategies:
  • Multipoint calibration and zero/span procedures
  • Use of certified calibration gas mixtures and dynamic preparation methods
  • Frequency of calibration recommendations to support traceability
• Interferences & secondary effects:
  • Spectral interferences from matrix gases (e.g., methane, CO2) and water vapor
  • Temperature, pressure, spatial homogeneity effects on spectroscopic response
• Measurement output:
  • Expression of results in amount fraction units and guidance on uncertainty estimation
• Safety: Warnings on hazardous materials and explosive risks when handling methane mixtures.

Practical applications - who uses ISO 2612:2023

• Biomethane and biogas producers validating gas quality before grid injection or vehicle fuel use.
• Natural gas grid operators and distribution companies monitoring NH3 to protect infrastructure.
• Analytical and testing laboratories seeking ISO/IEC 17025 accreditation for NH3 in (bio)methane testing.
• Engine and vehicle fuel system developers concerned with combustion impacts (NOx formation) and corrosion.
• Environmental and regulatory bodies assessing ammonia as an air pollutant or emission precursor.

Related standards

• ISO 6143; ISO 6145-1 (calibration gas preparation/comparison)
• ISO 10715 (gas sampling); ISO 9169 (performance of automatic measuring systems)
• IEC 61207-7 (TDLAS gas analyzers); ISO 16664 (handling of calibration gases)
• EN 16723-1 / EN 16723-2 (biomethane specifications referenced for application)

ISO 2612:2023 provides actionable, metrologically traceable procedures for reliable trace-level NH3 analysis in methane-based fuels using TDLAS, enabling consistent quality control, regulatory compliance, and safe handling practices.