Methane & wastewater / biogas

The TDL1200 uses Tunable Diode Laser Spectroscopy (TDLAS) — a laser-based absorption technique that targets the specific absorption wavelength of methane. It does not react to hydrogen sulphide, CO₂, or other gases commonly present in wastewater and biogas environments. The measurement range is 0–1200 ppm CH₄, with a stated accuracy of ±2 ppm.

Every TDL1200 reading carries a mandatory validity state — valid, degraded, or invalid — as a first-class output alongside the concentration value. The instrument surfaces thermal transients, pump faults, filter condition, and cell health through this validity state, so operators and data pipelines always know whether a reading can be trusted. Device health (ok / degraded / fault) is tracked independently from measurement validity.

The TDL1200 connects to SCADA or data loggers via RS-485 Modbus RTU, outputs a 4–20 mA signal for legacy analogue inputs, transmits wirelessly via LoRaWAN for remote monitoring, and logs locally to an SD card. All interfaces are available simultaneously. An integrated display shows the current reading and validity state locally at the instrument.

For facilities where broader site boundary monitoring is also required — ambient air quality around the perimeter, odour-proxy gases — DGEM units provide complementary multi-parameter monitoring on the same platform dashboard.

Standards & measurement classes

The TDL1200 can show a measurement excursion of up to ±5 ppm under rapid temperature transients exceeding 3.6 °C/hour. This matters for siting and interpretation and is disclosed pre-sales as standard.

Note: The TDL1200 is a precision environmental monitoring instrument, not an LEL safety detector. It is designed for continuous process and environmental monitoring in the 0–1200 ppm range. It is not a substitute for zone-rated LEL gas detection equipment where that is required by safety regulations.

Deployment scenario

An operator of three wastewater treatment works deployed TDL1200 analysers at the primary settlement and sludge digester areas of each facility. Each analyser connects to the site SCADA system via Modbus RTU and simultaneously transmits data to the Devlabs platform via LoRaWAN. A Devlabs outdoor gateway at each facility provides wireless coverage across the treatment process areas.

The platform is used to monitor concentration trends over time, correlate methane readings against process events (sludge dosing, digester agitation cycles), and generate reports for the facilities' environmental compliance records. Threshold alerts on the platform notify the on-call engineer when readings exceed configured process thresholds — not as a safety system, but as a process optimisation and early-warning tool.

The validity state on every reading is used by the SCADA integration to flag data quality — periods where the reading carries a degraded or invalid flag are marked in the historian and excluded from compliance trend calculations.