A municipal solid waste landfill serving Chengdu, Sichuan Province—handling approximately 3,500 tons of refuse daily—experienced two near-miss explosion incidents within six months during late 2024 and early 2025.
The Challenge: Legacy Catalytic Sensors Failed to Detect Hazardous Buildup
Landfill gas (LFG), comprising roughly 50% methane (CH₄) by volume, accumulates in decomposing waste layers and can reach explosive concentrations between 5% and 15% CH₄ in confined spaces. The facility’s legacy detection system relied on catalytic bead sensors—which have a response time exceeding 30 seconds and are highly susceptible to poisoning from hydrogen sulfide (H₂S) present in raw LFG streams.
Catalytic sensors provided only binary alarm output with no real-time concentration data or trend analysis capability—making it impossible to identify gradual gas migration patterns that precede hazardous accumulation events.
The Solution: TDLAS200B Laser Methane Detection System
The facility replaced its entire catalytic sensor network with TDLAS200B Tunable Diode Laser Absorption Spectroscopy units deployed at four critical locations: well head manifolds, compressor station enclosures, flare control panels, and administrative building intake zones.
- Measurement Principle: Wavelength-modulated laser absorption at 1,652 nm
- Minimum Detection: 0.1 ppm·m
- Range: 0–100% LEL
- Intrinsic Safety: Ex ia IIC T6 Ga
- H₂S Poisoning Resistance: Inherently immune
Early Warning Success: Averted a Catastrophic Event
Within the first month, the new system detected a slow but steady methane concentration rise (from 8% to 22% LEL over 72 hours) in Well Head Manifold B—a trajectory the previous catalytic sensors completely missed due to intermittent H₂S poisoning. Operators responded by increasing extraction well vacuum pressure, bringing levels back to normal within 48 hours.
Performance Comparison
| Metric | Catalytic Bead (Legacy) | TDLAS200B (New) |
|---|---|---|
| Response Time | > 30 seconds | < 3 seconds |
| Minimum Detection | 25% LEL (alarm only) | 0.1 ppm·m (continuous) |
| H₂S Poisoning | No — requires replacement | Inherently immune |
| Safety Rating | Ex d IIB T4 | Ex ia IIC T6 Ga |
| Calibration Interval | Monthly | Quarterly |
| Annual Maintenance Cost | ¥42,000 | ¥12,000 |
Why Switching to Laser-Based Detection Matters Globally
For landfill operators across Vietnam, Thailand, Philippines, Brazil, and beyond—where expanding waste volumes outpace existing monitoring capabilities—the transition from catalytic to laser-based detection represents one of the highest-ROI safety investments available. Typical medium-scale landfills achieve full system payback within 8–14 months.
To learn more about methane detection technology, visit EPA’s Landfill Methane Outreach Program. Explore our TDLAS200B product page or contact us for a customized assessment.
