Is it normal for gas to spray out when opening the fuel tank cap?

[McAlessandra]

Normal. Here are the relevant explanations: 1. Gaseous gasoline When opening the fuel tank cap and gas sprays out, this situation mostly occurs in summer. Gasoline is a rapidly evaporating liquid. When the liquid turns into gas, its volume increases. The gas you feel is actually gasoline, but in its gaseous state. 2. Pressure difference: During hot summer weather, the fuel pump inside the tank also generates heat when operating. Both gas and liquid expand when heated, with gas having a higher expansion rate than liquid. However, the entire fuel tank is a sealed space with a fixed volume. Therefore, the gaseous gasoline sealed inside the tank creates pressure that is higher than the external atmospheric pressure. Once the fuel tank is opened, a pressure difference is created between the inside of the tank and the atmospheric environment, causing the high-pressure gaseous gasoline inside the tank to spray out.