Marine fuel tank ullage system

摘要

A ullage system for a marine fuel tank that maintains an exact ullage space in all marine refueling situations including refueling in moving or pitching and rolling situations. The invention includes two ball valve assemblies that are inserted into a fuel tank at approximately the same level. The two assemblies typically are at opposite ends of the tank. One of the ball valves is smaller than the other in diameter. The smaller valve is coupled to an air vent; the larger valve is coupled to the filler tube. An important feature of the present invention is that it can typically be made to fit any marine fuel tank simply by changing the length of a vent tube to reach the correct ullage level for the tank at hand. The components of the present invention can be made from standard fuel valve materials.