The vertical distance from a fixture outlet to the trap weir should not be more than 24 inches. Fixture traps shall have a water seal of no less than two inches. Fixture traps is the section of the pipe that is in between a section of drainage and a trap. A trap weir on the other hand is the section in between the vent and a trap. This section is the most ancient tool that is of used of today because of its effectivity and cost effective method.