Massachusetts Plumbers Journeyman Practice Exam

What pitch should be used when installing horizontal drainage piping that is (3) three inches in diameter or smaller?

1. 1/8 inch per foot

2. 1/4 inch per foot

3. 1/2 inch per foot

4. 1 inch per foot

The correct answer is: 1/4 inch per foot

The correct pitch for installing horizontal drainage piping that is three inches in diameter or smaller is 1/8 inch per foot. This specific slope is crucial to ensure that wastewater flows effectively through the pipe without causing any standing water or potential blockages. The 1/8 inch per foot pitch allows for adequate drainage while also preventing excessive velocity that can lead to issues such as erosion of the pipe or disruption in the flow of solids in the wastewater. In plumbing practice, the choice of pitch is guided by factors such as pipe diameter and the nature of the fluid being transported. For smaller diameter pipes, a gentler slope is preferred to ensure that the wastewater moves smoothly through the system without creating undue turbulence. A steeper slope, such as 1/4 inch per foot or greater, may increase flow velocity to the extent that it can lead to solids settling or not being flushed effectively, which can cause blockages over time. Thus, utilizing a pitch of 1/8 inch per foot for horizontal drainage piping 3 inches in diameter or smaller ensures optimal performance and longevity of the plumbing system.