Alabama Contractors License Practice Exam

For a 2-inch waste and vent pipe, how many fixture units can it effectively serve?

1. 4

2. 6

3. 8

4. 10

The correct answer is: 6

A 2-inch waste and vent pipe can effectively serve a maximum of 6 fixture units according to plumbing codes and standards. Fixture units are a measure used to estimate the probable demand on a plumbing system. A 2-inch pipe is suitable for a moderate level of fixture demand, such as a small bathroom or kitchen, where peak usage is not expected to exceed the capacity of the pipe. In this case, the choice indicating 6 fixture units reflects the balance between the pipe's diameter, which influences its capacity to handle the flow of wastewater, and the expected load that a reasonable number of fixtures would place on it. Choosing a figure that is too high might suggest that the pipe could handle more flow than it is designed for, leading to potential issues like clogs or slow drainage. Conversely, underestimating the capacity could lead to inadequate plumbing for a given number of fixtures, leading to overloading and performance problems in the system. Understanding fixture units and the corresponding capacities of different pipe sizes is essential for effective plumbing design and ensuring that systems operate efficiently and reliably.