... (two-stage) Low: 25% LEL / High: 50% LEL Detectable Gas 2Toxic / Poisonous gas ( H2S, CO, NH3, NO, NO2, SO2, Cl2, ClO2, ... Measuring range and alarm threshold value can be adjusted. Gas Parameter list Gas TypeDetection RangeAlarm ThresholdSensor TypeNH3 (Ammonia)0-100 PPM25 ... PPMCH4 (Methane)0-100%LEL25%LEL / 50%LELCatalytic CombustionsensorC3H8 (Propane)0-100%LEL25%LEL / 50%LELH2 (Hydrogen)0-100%LEL25 ...