The "JJF 1674-2017 Specification for Benzene Gas detection alarm calibrating" applies to the calibrating of detection alarms with measurement upper limit not exceeding 100 μmol/mol of benzene gas. The standard covers benzene Gas detection instruments using photoionization and semiconductor detection principles, mainly for the monitoring of benzene gas concentration in environments such as workplaces. The instrument consists of detection elements, amplifying circuits, alarm systems and displays. Types include stationary and portable. Sampling methods are available in diffusion and suction. The principle of photoionization detection uses ultraviolet light ionization gas to generate a current to detect concentration, while the principle of semiconductor detection realizes concentration detection through conductivity changes. This specification ensures the accuracy and Reliability of calibrated instruments to meet the requirements of industrial safety and environment protection.