The carbon dioxide tester applies to the continuous online detection and site sound-light alarm of carbon dioxideconcentration in various industrial environments and specialenvironment, which functions as early warning for operationsafety on the dangerous site. Using the imported electrochemicalsensor and microcontroller technologies, the instrument isfeatured by stable signal, high precision and good repeatabilityand other merits, and its explosion-proof connection mode appliesto various dangerous sites. It can provide 24-hour continuousreal-time monitoring of indoor carbon dioxide concentration,display date, detection time, temperature and humidity data on the detection site automatically. The instrument is compatible withvarious control alarms, PLC, DCS and other control systems,which can realize site alarm, remote monitoring and alarmfunction at the same time