Independent air chamber structure, fast response, good long-term stability. Each unit can be switched with each other, automatically track the zero point to prevent drift, and multi-level calibration. Standard infrared remote control can be operated without open cover in dangerous occasions, remote control distance of 15 meters, simple and practical. It can communicate with the computer, monitor the concentration of the on-site probe in real time through the host computer on the computer, and store, analyze and print the data on the computer. Can detect the poisonous and harmful gas, flammable and explosive gas, the concentration of volatile organic gas and in the field display real-time density and standard signal output, signal stability, high sensitivity and precision, etc. The flame-proof connection mode is suitable for all kinds of dangerous sites.