A 2-inch drain serves 8 fixture units, and the vent serving it has a developed length of 40 feet. Using the UPC's Table 703.2 vent columns, what is the minimum vent diameter?
Not quite. The answer is B: 1.5 inch
The vent must be at least 1¼ inches and at least half the drain's diameter, so the floor is 1¼ inches. A 1¼-inch vent is rated for only 1 fixture unit, which is too small for 8 FU. A 1½-inch vent is rated for 8 FU and 60 feet, which covers both the load and the 40-foot run, so 1½ inches is the minimum — stepping up to 2 inches would work but is not required.
Reference: UPC 2021 Table 703.2 (vent columns); §904.1 (Size and length of vents)
Checked against the official text
Table 703.2 is not supplied at the exam desk and must be memorized. The 2015 edition's vent columns were not read directly for this question; confirm against your 2015 book.
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