1:4~20mA Gas Alarm Controller 2:Imported sensor 3:Explosive-proof 4 ... recognition and protection the concentration of sensors , short-circuit and open-circuit of sensors, and automatic fault detection .3. ... 4~20mA international stand current signal,(0~20mA broken circuit ,2mA sensor fault, 22mA over concentration),can be ... range:86~106kPa 4~20mA Gas Alarm Controller for commercial and industrial use