Massachusetts Plumbers Journeyman Practice Exam

Which type of traps are explicitly prohibited?

1. Bell traps

2. Drum traps

3. Crown vented traps

4. P traps

The correct answer is: Crown vented traps

Crown vented traps are explicitly prohibited because they can lead to drainage issues and are more prone to trapping air, which ultimately affects their effectiveness in maintaining a water seal. The design of crown vented traps can also facilitate siphoning, making them less reliable in preventing sewer gases from entering living spaces. Ensuring that proper trap designs are used is crucial in maintaining sanitary conditions and optimal plumbing function. Other trap types, like bell and drum traps, are often discouraged in modern plumbing, but it is the crown vented traps that are explicitly prohibited because of the unique problems they present compared to the more accepted designs like P traps.