JJF 1368-2012 "Combustible Gas detection alarm type evaluation outline" is applicable to the type evaluation of various types of combustible Gas detection alarms (referred to as instruments) used in non-mine operating environments and civil places. This outline refers to a number of standards such as JJG 693-2011 "Combustible Gas detection alarm", GB 12358-2006 "General technical requirements for workplace environment Gas detection alarm instrument", etc. According to the detection principle, the instrument is divided into catalytic combustion type, thermal conductivity type, semiconductor type and infrared absorption type. Sampling method is divided into diffusion type and suction type, and the use method is divided into portable and fixed type. It is mainly composed of detection elements, amplification circuits, alarm systems and displays, etc., which are used to monitor the concentration of combustible gases in the environment. Once the concentration exceeds the set value, an alarm signal will be issued.