Red Seal Plumbing Practice Exam

What is the correct minimum size of a fresh air inlet for a building trap?

1. 2"

2. 3"

3. 4"

4. 6"

The correct answer is: 4"

A 2": This is too small of a size for a fresh air inlet as it may not provide enough ventilation for the building trap. B: 3": This is also too small and may not provide sufficient ventilation for the building trap. D: 6": This is too large and may result in excessive ventilation, which can lead to loss of trap seal and sewer gas entering the building. C: 4": This is the correct minimum size for a fresh air inlet for a building trap as it provides enough ventilation without risking loss of trap seal. A 4 inch fresh air inlet is the industry standard for building traps and ensures proper ventilation and prevention of sewer gas leaks.