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KNF-700G Underground Gas Detection Terminal: One Device, Seven Parameters, Zero Consumable Laser Methane Sensing

Shenzhen, China — KaiNaFu has released the KNF-700G underground gas detection terminal, a fully integrated multi-parameter monitoring station purpose-built for sewer networks, inspection wells and manholes. Combining tunable diode laser absorption spectroscopy (TDLAS) methane measurement with electrochemical hydrogen sulfide, carbon monoxide and oxygen sensing, the terminal delivers seven simultaneous measurements — methane, H2S, CO, O2, barometric pressure, temperature and optional liquid level — from a single IP68, explosion-proof housing installed 15 to 20 cm below ground level.

Municipal operators have long struggled with the trade-off between data density and maintenance cost. Conventional catalytic bead and pellistor methane sensors drift, saturate in humid well shafts and require frequent recalibration, which turns every manhole into a recurring service visit. The KNF-700G removes that bottleneck by measuring methane optically: the laser passes through the sampled gas, and absorption at the selected wavelength gives a direct reading with no consumable sensing element, no cross interference from humidity and a service life exceeding three years.

Product Highlights at a Glance

• TDLAS methane sensing — 0 to 20 %VOL range, 0.01 % resolution, more than three years of life with no consumable sensor head.
• Seven parameters in one terminal — CH4, H2S, CO, O2, barometric pressure, temperature and optional liquid level with a maximum error under 5 mm.
• IP68 and EX d IIC T6 Gb — designed for permanent immersion risk and explosive atmospheres inside drainage shafts.
• 4G wireless with GPS and Beidou positioning — each alarm report carries the exact well location, so dispatch crews arrive at the right manhole.
• 2+ years of battery autonomy — a 3.6 V high-capacity lithium pack runs the terminal in factory mode for more than 24 months; three years of data traffic is included.
• Air pump sampling — the terminal keeps measuring even when the shaft is flooded, and the external expansion port accepts additional sensing functions.
• 30-minute sampling, 24-hour upload — both intervals are adjustable, and threshold exceedance triggers an immediate upload of up to three alarm events per day.

Detection Capability

Technical Specifications

Deployment Scenarios

• Smart sewer and drainage networks — continuous odor and combustible gas monitoring across hundreds of wells, with GIS-linked alarm reporting.
• Municipal gas utility safety — early warning of methane accumulation in inspection chambers along buried gas mains.
• Industrial wastewater plants and utility tunnels — confined space entry risk control before and during maintenance work.
• Underground utility corridor projects — combined gas, liquid level and positioning data feeding a single SCADA dashboard.

Installation is deliberately simple. The mounting frame is fixed to the shaft wall with expansion screws or cement nails, and the terminal sits on the frame. Where field signal strength is weak, a split antenna can be routed into a shallow ground slot 18 cm long, 7 cm wide and 3 cm deep, then covered with cement or asphalt to restore the road surface. When the radar path for liquid level measurement is obstructed, a rotating arm accessory repositions the sensor without relocating the terminal.

Availability

The KNF-700G underground gas detection terminal is available now from KaiNaFu, Shenzhen, China. Minimum order quantity is one piece, supply capacity is 500 units per month, lead time is 10 to 20 working days, and payment terms are T/T. Each unit ships in export cartons with shock-proof foam and carries a one-year warranty from the date of delivery. OEM branding, custom H2S ranges, RS485 wired variants and bulk project pricing are available on request.