Explain the function of a vent in a sanitary drainage system and the consequences of inadequate venting.

A vent in a sanitary drainage system provides air circulation within the pipes, protecting trap seals and ensuring proper drainage. The primary function of a vent is to prevent pressure imbalances that can siphon water out of the traps, which would allow sewer gases to enter the building. When wastewater flows through a drainage pipe, it creates a pressure differential. Without a vent, this pressure differential can either create a vacuum behind the flowing water, siphoning the water out of the trap, or create positive pressure in front of the water, forcing sewer gases through the trap seal. Vents allow air to enter the drainage system, equalizing the pressure and preventing these siphoning effects. There are several types of vents, including individual vents, which connect directly to the trap arm of a fixture; common vents, which serve multiple fixtures; and main vents, which extend from the building drain to the open air above the roof. The consequences of inadequate venting can be significant. The most common consequence is trap seal loss, which allows sewer gases to enter the building, creating unpleasant odors and potentially exposing occupants to harmful gases. Slow drainage is another consequence, as the lack of air circulation can impede the flow of wastewater. Gurgling noises from the drains can also occur, as air is forced through the water in the trap. In severe cases, inadequate venting can lead to backflow, where wastewater is drawn back into the building's water supply, creating a health hazard. Proper venting is essential for maintaining a safe and sanitary plumbing system.