What is the primary function of the oil vent pipe?

The primary function of the oil vent pipe is to allow air to escape from the tank when it is being filled. This is essential because as the tank fills with oil, the air inside needs to be displaced to prevent pressure buildup, which can lead to leaks or other issues. When the tank is filled without a vent, it can create a vacuum that could hinder the filling process or damage the tank by pulling it into a collapsed state.

By providing a pathway for the air to escape, the vent pipe ensures that the filling process is smooth and safe. This function is crucial for maintaining the integrity and safety of the oil tank and for preventing potential hazardous conditions related to pressure changes.