Abstract: The paper takes the city gas pipeline leakage alert zones as the research object. By establishing regional typical scenes, a series of different univariate comparison scene combinations, including pipeline pressure, leakage duration, wind speed, temperature, and solar radiation intensity, are set to simulate pipeline damage and combustible gas leakage and diffusion behavior. It is proposed that the steady-state arrival time and the size of the influence range are used as characteristic indicators to compare and analyze the influence of different condition variables. The results show that, within each univariate scenario group, the inhalation toxicity range is the smallest; the flammable range is the largest, and the ranges at all levels are slightly larger than the explosion damage range. comparing each univariate scene group horizontally, in the case of continuous leakage, the leakage duration does not affect the sizes of the three danger zones of inhalation toxicity, flammability, explosion damage and steady-state arrival times, but only affects the maintenance time of the impact range. the other four parameters affect the sizes of the danger zone and steady-state arrival times to varying degrees; the degree of influence is: pipeline pressure> wind speed> solar radiation> ambient temperature. Under univariate comparison conditions, the values of the three hazard ranges and steady-state arrival times increase with the increase of pipeline pressure or ambient temperature, and decrease with the increase of wind speed or solar radiation intensity. Obtain the quantitative influence and change trend of the two characteristic indicators with different values of each variable. Comparing the two types of gas leakage accident scenarios, continuous leakage and instantaneous leakage, the different rules are obtained. And a targeted analysis puts forward the key points that the fire rescue team should pay attention to when dealing with urban gas pipeline leakage accidents.

Key words: fire fighting; city gas lines; leakage diffusion; emergency rescue; alert zones