Overview
EN ISO 16960:2014 - Natural gas - Determination of sulfur compounds - Determination of total sulfur by oxidative microcoulometry - is a CEN-endorsed ISO method for measuring total sulfur in pipeline natural gas. The method covers measurement of total sulfur in the range 1 mg/m³ to 200 mg/m³ by oxidative microcoulometry; samples above 200 mg/m³ can be analysed after dilution with a suitable sulfur‑free solvent. The standard specifies principle, reagents, apparatus, test preparation, procedure, calculation and precision requirements.
Key topics and technical requirements
- Test principle: oxidative pyrolysis converts sulfur compounds to SO2, which is titrated in a microcoulometric titration cell. Iodine consumed by SO2 is regenerated by electrolysis; the electrical charge consumed (Faraday’s law) is used to calculate sulfur mass concentration.
- Scope: pipeline natural gas; total sulfur determination (1–200 mg/m³); dilution allowed for higher concentrations.
- Reagents and gases:
- Test water to ISO 3696 Grade 3.
- Glacial acetic acid and potassium iodide (analytical purity).
- Oxygen ≥ 99.99 % (max 0.01 % sulfur-containing gases).
- Carrier gas (argon/helium/nitrogen) ≥ 99.99 % (max 0.01 % sulfur-containing gases).
- Apparatus:
- Converter with three heating zones: preheat ~800 °C, combustion ~900 °C, exit ~800 °C (±20 °C).
- Titration cell with electrolysis and indicator/reference electrodes.
- Microcoulometer that records current/time and displays sulfur content.
- Flow controller, electromagnetic agitator, calibrated air‑tight syringes (0.25–5 ml) and 25 ml volumetric flask.
- Preparation details: electrolyte recipe (0.5 g KI in 100 ml water + 5 ml acetic acid, diluted to 1 L; store in brown bottle; shelf life ~3 months).
- Quality and calibration: use calibration gas mixtures per ISO 6142/6144/6146; recommended calibration gas sulfur spec (e.g., H2S) close to sample concentration. Sampling guidance per ISO 10715.
- Precision: the standard includes repeatability and general precision provisions for method performance.
Applications and users
- Who uses it: gas analysis laboratories, transmission and distribution operators, pipeline quality control teams, custody transfer labs, regulatory and environmental monitoring bodies.
- Practical uses:
- Routine quality control of pipeline natural gas.
- Compliance testing for contractual sulfur limits and environmental regulations.
- Method for labs needing trace-to-low-level total sulfur quantification with rapid, direct measurement.
Related standards
Keywords: EN ISO 16960:2014, natural gas, total sulfur, oxidative microcoulometry, sulfur determination, pipeline natural gas, microcoulometer, gas analysis.