For which purpose is a vent pipe primarily used in plumbing systems?

A vent pipe is primarily used to equalize pressure in the drainage system. Its main function is to allow air to enter the plumbing system, which helps to prevent the formation of negative pressure (or vacuum) in the drainage lines. When water drains from fixtures, it can create a suction effect that might impede flow or cause traps to empty, leading to sewer gases potentially entering the living space. By equalizing the pressure, vent pipes ensure that water can flow freely through the system without disruption.

This function is crucial for maintaining proper drainage and the overall health of the plumbing system. Without adequate venting, you may experience slow drainage, gurgling sounds in the plumbing, or even the presence of unpleasant odors due to the backflow of sewer gases. Therefore, the role of a vent pipe is central to promoting efficiency and safety in plumbing installations.