A vent must rise at least 6 in. above the fixture flood rim before running horizontally. If necessary, a pair of 45- degree offsets may be used, as shown in the figure below.

A vent must rise above a fixture’s flood rim before turning horizontally. If an offset is needed below the rim, use sixteenth or eighth bends. Do not use quarter bends.
A vent must rise above a fixture’s flood rim before turning horizontally. If an offset is needed below the rim, use sixteenth or eighth bends. Do not use quarter bends.