KNF-700 / KNF-700G Underground Multi-Parameter Gas Detection Terminal The KNF-700 and KNF-700G are integrated underground gas detection terminals developed for sewer and inspection well (manhole) monitoring, including odor monitoring in drainage networks. Methane concentration is measured by tunable diode laser absorption spectroscopy (TDLAS), which delivers excellent selectivity and long-term stability without consumable sensors. Hydrogen sulfide, carbon monoxide, oxygen,