Waterproof, dustproof, explosion-proof, shockproof, antistatic, anti-electromagnetic interference. Automatic zero-point tracking, multi-level calibration of target point, improve the linearity and accuracy of measurement. Data recovery function: Selective recovery or full recovery. Concentration calibration misoperations are automatically identified and prevented to avoid defects caused by human factors. The three display modes can be switched, and you can set whether to display the maximum value, minimum value, and gas name, and you can view the historical record graph. Application occasions: Petroleum, environmental protection, gas distribution, storage, flue gas analysis, air treatment and other occasions that require fixed installation and online detection of gas concentration.