There is an iron chain at the bottom of the tanker, which is specially used to transport gasoline on the expressway. What is the use of this chain?

It is because when the car is driving on the road, it will rub against the air and generate static electricity. When static electricity accumulates on the car body to a certain extent, sparks will be generated due to the discharge caused by people touching the car body or other objects touching the car body, thus igniting or detonating flammable and explosive articles on the car. Therefore, it is necessary to install chains under the car to release static electricity to the ground in time to eliminate hidden dangers. Sometimes when we get off the bus, we accidentally touch the door or the metal part of the car body, and sometimes we get an electric shock. This is the reason why this static electricity is released to the ground through the human body, so we will feel numb, and sometimes people will be corona if static electricity accumulates too much.