Question 55

In a PVC-DWV horizontal building drain, a sanitary tee fitting is NOT allowed.

In a PVC-DWV horizontal building drain, the use of a sanitary tee fitting is prohibited due to potential issues with drainage and venting. Proper fittings must be used to ensure effective flow and prevent blockages.

A) which of the following fittings is NOT allowed

This option correctly identifies the focus of the question, as it directly asks for the fitting that is not permitted in a horizontal drain. Since the question is about identifying an incorrect fitting, it is indeed the correct choice.

B) Sanitary tee

The sanitary tee is not allowed in a horizontal drain because it can create a situation where wastewater could flow improperly, potentially leading to clogs or sewer gas issues. Therefore, this option accurately reflects a fitting that should not be used.

C) Short sweep

A short sweep fitting is allowed in a horizontal drain as it is designed to provide a smoother transition for the wastewater flow. This option does not meet the criteria of being an incorrect fitting.

D) Long sweep

Long sweep fittings are also permitted in horizontal drains as they allow for a gradual change in direction, minimizing resistance and promoting better flow. Consequently, this option is not the correct answer.

E) Wye

A wye fitting can be used in horizontal drains as it facilitates the connection of different pipe angles without disrupting the flow. This option is therefore not applicable as an incorrect fitting.

Conclusion

The correct answer identifies that the sanitary tee is not allowed in a PVC-DWV horizontal building drain due to its potential to cause drainage issues. All other options, including the short sweep, long sweep, and wye fittings, comply with regulations and are suitable for use in horizontal drainage systems. Thus, they do not fulfill the criteria set by the question.