Abstract: In order to study the influence of a small amount of gasoline liquid vapor on the explosion characteristics of low-concentration methane, a 20 L spherical explosion vessel was applied to study the explosion characteristics of 1 mL and 2 mL gasoline liquid that mixed with air alone. With varying methane concentration, the explosion characteristics of low-concentration methane mixed with 1 mL and 2 mL gasoline were studied. The effect of gasoline addition on the lower explosion limit of the entire system was analyzed. The results indicate that gasoline has a very significant impact on the explosion of methane-air mixture. When the addition amount is 2, 2.5 and 3 mL, the pmax is 0.11, 0.79 and 0.82 MPa, respectively, and the corresponding (dp/dt)max is 10.57, 32.52 and 108.53 MPa/s, respectively. When the methane concentration is 6% and the gasoline addition amount is 2 mL, the pmax is 1.01 MPa, which is 31% higher than when 1 mL gasoline is added, and 320% higher than that when no gasoline is added. The lower explosion limit of the gas mixture become lower than the lower explosion limit of each in the air. The mixture of 1 mL gasoline and air is not explosible, while it can explode when mixed with methane with a concentration of ≥3.5%. When 2 mL gasoline is mixed with methane whose volume concentration is ≥0.3%, the gas mixture can still explode. This work can provide data support for the explosion and prevention of leaking gas and other flammable liquid vapor mixtures in enclosed and semi-enclosed spaces.

Key words: gasoline vapor, methane, explosion pressure, lower explosion limit