46 CFR § 153.350 - Location of B/3 vent discharges.
Except as prescribed in § 153.353, a
(a) At the highest of the following points:
(1) 6m (approx. 19.7 ft) above the weatherdeck.
(2) B/3 above the weatherdeck.
(3) 6m (approx. 19.7 ft) above a walkway, if the walkway is within a 6m (approx. 19.7 ft) horizontal radius from the vent discharge.
(b) At least 15m (approx. 49.2 ft) from air intakes for, or openings into, accommodation and service spaces.