The CC33 uses catalytic combustion (CC) to detect flammable gases and vapors such as methane, propane and hydrogen as well as ammonia. Their long-life sensors make 33 series transmitters an economical solution for detecting a wide range of combustible gases in the measuring ranges 0 to 100 % LEL and 0 to 4 % by volume (NH3). Its automatic temperature compensation and the linearisation of the measuring signals ensure high measuring accuracy. In the event of an alarm, two red LEDs light up and the display color changes to red. The three optional relay outputs can be used to automatically trigger an explosion-proof buzzer, visual warnings such as flashing lights or the ventilation in case of an alarm.