Methane analyzer Off-Gas System

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The Off-Gas System measures nitrous oxide (N2O), methane (CH4) and CO2 directly above the aeration tank of your wastewater treatment plant. A floating hood collects the off-gas from exactly 1.00 m² of tank surface, and the gas analyzer in the outdoor cabinet calculates the emission rate in mg/(m²·h). Your greenhouse gas reporting is based on measured values instead of default emission factors.
Applications:

• Municipal and industrial wastewater treatment plants, aeration tanks with fine-bubble aeration
• N2O and methane reporting under the revised EU Urban Wastewater Treatment Directive (transposition by July 2027)
• Proving the effect of process optimisation, e.g. aeration control and nitrogen removal
• Continuous monitoring and measurement campaigns

Two versions, same design:

• System Smart with Smart Control 300: N2O detection limit 10 ppmV, for operational monitoring and reporting
• System Expert with GA 320: N2O detection limit 0.5 ppmV, measurement uncertainty ≤ 2 %, compensation of humidity and cross-sensitivities, for low emissions and measurement campaigns
• The Gas Dome 300 hood, the gas path and the outdoor cabinet are identical in both systems.

Your benefits:

• Emission rate, not just concentration: E = c × Q / A, calculated in the analyzer firmware, no extra software
• No blower, no test gas, no consumables: the gas flows by its own pressure, and the zero point is corrected with every measurement (NDIR dual-pressure reference).
• Your data stays with you: 4–20 mA, relays, RS-232, optional Profibus DP, Modbus TCP, EtherNet/IP or Profinet. No cloud, no subscription.
• A second measuring point at a fraction of the cost, because cabinet and analyzer are already in place.

Technical data (extract):

• Components: N2O, CH4, CO2, optional O2 (electrochemical, 0–30 vol.-%)
• Ranges Smart: N2O 0–2,000 ppmV, CH4 0–1,000 ppmV, CO2 0–5 vol.-%
• Ranges Expert: N2O 0–2,000 ppmV, CH4 0–10,000 ppmV, CO2 0–10,000 ppmV
• Collection area: 1.00 m² per hood, flow 0–20 m³/h without blower
• Uncertainty of the emission rate at 20 / 10 / 5 m³/h: Expert ±5.2 / 6.8 / 10.3 %, Smart ±11.1 / 11.9 / 14.2 %
• Measuring points: one or two, 25 m hose (ID 40 mm) each
• Outdoor cabinet: IP 55, IK 10, 100 W heater; Smart 1200 × 600 × 400 mm, Expert 1200 × 600 × 600 mm

Good to know: the system determines the emission rate of a defined area for operation, optimisation and operational reporting. It is not a CEMS and does not replace regulatory emission measurements. Every system is assembled and tested at our factory in Herten, Germany.
Full details: Off-Gas System Smart and Expert brochures and comparison sheet (06.10.2026) under Catalogs.