For the safety of general tank truck manufacturers, a fire-proof cap is installed in front of the exhaust pipe, which provides a safer transportation for the tanker. Because the fuel is not fully burned, there will be Mars. The tanker is generally pulling dangerous goods and flammable liquids. The exhaust pipe is too close to the tanker oil, which is easy to cause fire, the exhaust pipe is placed in front, and then added. Put on the fire-proof cap, it is to stay away from the oil in the tanker car, there is no Mars, it is not easy to accident, for safety reasons, so the exhaust pipe should not only be installed in front, but also install a fire-proof cap.