Plumbers should place the connection for the branch vent at least how far above the flood level?

Plumbers should place the connection for the branch vent at least how far above the flood level?

• A. 6 inches or more above the flood level
• B. 2 inches above the flood level
• C. 1 inch above the flood level
• D. 0 inches (at flood level)

Answer: (A)

Vent placement is about keeping the vent path open so air can enter as the fixture drains, preventing siphoning of the trap. The branch vent must connect high enough above the flood level of the fixture (typically above the flood level rim of the highest fixture served) so that wastewater cannot reach the vent opening and block it. When the vent stays clear, it can admit air to relieve negative pressure and protect the trap seal. If the connection were closer to or at the flood level, water could rise into the vent, flooding it and defeating its purpose. Therefore, the minimum height is six inches above the flood level.

Vent placement is about keeping the vent path open so air can enter as the fixture drains, preventing siphoning of the trap. The branch vent must connect high enough above the flood level of the fixture (typically above the flood level rim of the highest fixture served) so that wastewater cannot reach the vent opening and block it. When the vent stays clear, it can admit air to relieve negative pressure and protect the trap seal. If the connection were closer to or at the flood level, water could rise into the vent, flooding it and defeating its purpose. Therefore, the minimum height is six inches above the flood level.