73. When may one bathtub and one laundry sink be installed on a 1 1/2-inch horizontal waste branch without re-venting
Answer: A
One bathtub and one laundry sink may be installed on a 1 1/2-inch horizontal waste branch without re-venting when the most remote fixture is within a developed length of 3 feet 6 inches from a main vented line.
This installation is permissible because the distance specified ensures adequate drainage and venting for both fixtures, adhering to plumbing code requirements.
A) When the most remote fixture is within a developed length of 3 feet 6 inches from a main vented line
This option is correct as it specifies the maximum distance allowed for the most remote fixture from a main vented line, ensuring proper venting and drainage. Compliance with this distance is crucial to prevent trapping and maintain effective waste flow.
B) When the most remote fixture is within a developed length of 5 feet from a main vented line
This option is incorrect because it exceeds the maximum distance of 3 feet 6 inches specified in the correct answer. Installing fixtures at this distance without proper venting could lead to drainage issues and potential code violations.
C) When the most remote fixture is within a developed length of 6 feet from a main vented line
This option is also incorrect as it further exceeds the specified maximum distance. Allowing a distance of 6 feet would compromise the performance of the waste branch and could cause problems with air balance and drainage.
D) They cannot be installed there. The horizontal branch is too small
This option is incorrect because the size of the horizontal waste branch is adequate for a bathtub and a laundry sink when installed according to the specified distance. The 1 1/2-inch diameter is permissible under code guidelines for such fixtures when within the appropriate distance from a vented line.
Conclusion
The correct answer is definitively right because it adheres to plumbing regulations that ensure proper venting and drainage for the fixtures in question. All other options fail either by exceeding the allowable distance or misrepresenting the capability of the waste branch to accommodate the fixtures.