Understanding Sizing of Offset Relief Vent in Plumbing

Sizing of Offset Relief Vent in Plumbing

In Engineering, specifically in plumbing, an offset relief vent is sized based on the pipe that it is relieving. An offset relief vent is a venting system component designed to manage and balance air pressure within the plumbing systems and prevent water seal traps from siphoning.

The size of the relief vent should be at least half the diameter of the drain it services, but it shouldn't be less than 1-1/4 inches, which is the minimum established by most plumbing codes.

For example, if an offset drain is 3 inches in diameter, the offset relief vent should be at least 1.5 inches. However, as always in design considerations, local code requirements must be checked as they vary across different regions.