Red Seal Plumbing Practice Exam

If a kitchen sink in a single family dwelling unit is individually vented, it requires a vent pipe that is how many inches?

1. 1"

2. 1 1/4"

3. 1 1/2"

4. 2"

The correct answer is: 1 1/4"

A 1" is too small for a vent pipe in a kitchen sink. It would not provide enough air to properly vent the drainage system, potentially causing issues with water flow and smells. C: 1 1/2" is too large for a vent pipe in a kitchen sink. This size is typically used for larger fixtures, such as a bathtub or shower. D: 2" is also too large for a vent pipe in a kitchen sink. This size is typically used for larger fixtures or multiple fixtures that require proper ventilation, such as a toilet and sink connected to the same drain line. Therefore, the correct answer is B: 1 1/4". This size is standard for individual ventilation of a standard kitchen sink in a single family dwelling unit.