Why venting protects the trap seal, individual/common/wet/circuit/island vent types, air admittance valves, vent sizing, and the most common venting code violations.
A trap seal can fail two ways with nothing to do with how well the trap itself is built: self-siphonage and induced siphonage pull it out, back-pressure blows it out. This module works through the vent types code recognizes to prevent both — individual, common, wet, circuit, loop, and island venting — plus air admittance valves as a mechanical alternative to a roof penetration, how a vent is actually sized, and the recurring violations (crown venting chief among them) that let a trap seal fail despite a vent being present on paper.
By the end of this module you should be able to read any DWV and vent drawing against one physical test: does every trap on it stay close enough to atmospheric pressure on both sides, under both a single fixture's own discharge and a full stack event — the same test this module and Module 8 build together.