A garage sand trap must be provided with what size vent?

The requirement for a garage sand trap to have a vent size of 4 inches is based on plumbing codes and standards which take into account the function and flow of wastewater from such traps. A 4-inch vent is adequate to ensure that air can circulate through the system, preventing negative pressure situations that would otherwise inhibit proper drainage. This sizing helps ensure that any gases are effectively vented outside and that there is minimal risk of siphoning or backpressure, which could cause drainage issues.

Having a vent of this size also allows for adequate airflow to accommodate the potential volume of wastewater that might be entering the trap, particularly in a busy garage environment where multiple sources could contribute to the flow at once. Proper venting is critical in maintaining the functioning of the plumbing system as it avoids issues like clogs or system failures due to inadequate airflow.