From May 16 to 17, 2022, when the fire rescue organization of Yongkang City, Zhejiang Province inspected a company, it was found that the company had problems affecting safety production such as disabling the combustible gas alarm device without authorization, and a large number of paints and thinners such as 26 barrels of paint stabilizer and 16 barrels of varnish of a certain brand were stored in the area where the combustible gas alarm was closed. The fire rescue agency ordered the company to rectify immediately according to law, and transferred the clues of the case to the Yongkang Public Security Bureau for handling. Li Mouyuan was sentenced to eight months' imprisonment by the Yongkang Municipal People's Court for the crime of dangerous operation because he knew that shutting down the combustible gas alarm would lead to the inability to monitor the concentration of combustible gas released in the production process in real time, and there were major hidden dangers in safe production, so he shut down the alarm without authorization to save production costs, which would have the real danger of major casualties or other serious consequences.

    Combustible gas alarm plays a good early warning role in the petrochemical and industrial production environment. It is the guarantee to prevent major accidents, ensure the safe production of enterprises, and ensure the safety of production personnel and surrounding people.

    What is the difference between the primary and secondary alarm points of the gas detector?

    The fixed combustible gas detector is usually equipped with two lower limit alarm points (the specific value is related to the model of the alarm host): "10% LEL" is the first level alarm, and "25% LEL" is the second level alarm. The portable gas detector is usually equipped with a lower limit alarm point of "25% LEL" and a upper limit alarm point of "50% UEL". Alarm point. The lower explosive limit (LEL) and upper explosive limit (UEL) are important indicators of combustible gas detector.

    The following is a simple example to analyze the alarm point setting and the upper and lower explosion limits:

    For example, the lower explosive limit of methane is 5% VOL. Divide the "5%" volume ratio into 100 equal parts, and let the "5%" volume ratio correspond to "100% LEL", that is, 100% LEL equals 5% VOL. When the value reaches the concentration of 25% LEL, it is equivalent to 1.25% VOL of methane. There is still a certain distance from the lower explosive limit. Take timely ventilation measures, and close the gas source to safely deal with potential hazards at the point.

    In a word, the reason why the gas detector sets multiple alarm points is to give users enough time to escape or solve problems.

    How to set the primary and secondary alarm points and range of the alarm?

    Measuring range of combustible gas detector: 0% LEL~100% LEL; Fixed combustible gas alarm shall be divided into at least two levels, the first level alarm threshold shall not be higher than 25% LEL, and the second level alarm threshold shall not be higher than 50% LEL. The catalytic combustion sensor has good linearity and 1LEL resolution, and is a product for testing the high performance-price ratio of the gas sensor.

    The setting of combustible gas/toxic gas alarm device plays a vital role in all production enterprises. In the daily production work, we should do a good job in the hierarchical management and control of safety risks and the troubleshooting and treatment of hidden dangers. We must not seek benefits, reduce safety, strengthen safety production management, and improve the level of intrinsic safety.

    When producing or storing combustible gas, Class 1 combustible gas is classified as Class A fire hazard, and Class 2 combustible gas is classified as Class B fire hazard.

    Class I generally refers to combustible gases with lower explosive limit (volume%) less than or equal to 10, such as hydrogen, methane, ethylene, acetylene, ethylene oxide, vinyl chloride, hydrogen sulfide, water gas, natural gas and most other combustible gases.

    Class II is followed by combustible gases with lower explosive limit (volume%) greater than 10, such as ammonia, carbon monoxide, producer gas and other few combustible gases.

    GYC1201, 1101 and MJC4 series launched by Guangyuan Technology are catalytic combustion sensors, which are widely used in industrial alarm, domestic gas alarm and mining fields.