... and good anti-interference capacity. In addition, it has two-stage alarm function with acoustic and visual signals.KB501SG is ... CH4, LPG, Natural Gas, etc. )Measuring Range0~100% LELAlarm Threshold (two-stage) Low: 25% LEL / High: 50% LEL Detectable Gas 2Toxic ... Signals Three-wire system 4~20mA standard signals outputAlarm OutputTwo-way electrical relay tip output (30V 2A)Alarm SignalAcoustic and light ...