Independent detector by catalytic technology for the detection of butane-propane, methane- natural gas and hydrogen with relay. Independent functioning: without connection to any central. Allows the automatic selection of the gas to detect, between all the available gases, through a protocol established with a jumper. Detection range from 0 to 100% L.I.E. Optical state and sensor breakout indicator. 1 alarm relay output programmable between 2 levels (20% LIE / 50% LIE), instant/retarded disconnection, programmation retard of connection and initial state of the relay in repose. Power 10V to 30V DC. Calibrated in factory with span gas. No need to recalibrate in the installation. Easy verification and maintenance operations by a single worker. Resistant to silicone vapours (HDMS).