Recently, there was a discussion within ASPE Connects Open Forum regarding “Venting Vertical Offsets in Sanitary Drainage Piping.” The author indicated that such vertical offsets have been perplexing to him for many years, and that he had done much research and reading on this subject without finding an acceptable answer to the question: “Do you need to vent vertical offsets in sanitary drainage piping?”
This, in my judgment, gets into a basic understanding of flow within the piping system and the reasoning for providing vents around these offsets.