Section 183.520 - Fuel tank vent systems(a) Each fuel tank must have a vent system that prevents pressure in the tank from exceeding 80 percent of the pressure marked on the tank label under § 183.514(b)(5) .(b) Each vent must: (1) Have a flame arrester that can be cleaned unless the vent is itself a flame arrestor; and(2) Not allow a fuel overflow at the rate of up to two gallons per minute to enter the boat.CGD 74-209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 77-98, 42 FR 36253, July 14, 1977