The CL-20A-C is a gas detector that immediately detects the concentration of natural gas (methane) in the air and provides an early warning by sounding an alarm when 3% ~ 20% of the Lower Explosive Limit (LEL) is reached. The module utilizes a widely used semiconductor gas sensor that combines the advantages of low cost and high reliability to meet the requirement of a 5-year life span for residential use. The design of high sound pressure and alarm linkage function solves the problem that the alarm sound cannot cover a large area due to the sound insulation planning of different floors and spaces. Considering the needs of different alarm types, the module provides 1 relay output, which can be used to connect to the alarm light or other alarm devices to enhance the alarm effect, or to connect to the gas shut-off valve to shut off the gas pipeline and stop the gas delivery. 110VAC power supply and wall-mounted quick-release design allow users to quickly dismantle and install without the need to prepare a DC transformer, which makes it more convenient to deploy and maintain the module. In order to meet the needs of the Internet of Things (IoT), the detector itself provides a CAN bus communication function. Through the integration with the fire information system, the graphical control software can obtain the status of the gas detector in real time, realizing the purpose of monitoring the fire safety of the building.