The two parts of a trap used to measure the depth of the trap seal?

• A. Inlet and outlet
• B. Crown weir and top of the dip
• C. Top lip and bottom
• D. Weir and baffle

Answer: (B)

Trap seal depth is measured from the crown weir to the top of the dip. The crown weir is the highest edge at the trap’s outlet that sets a reference point for the flowing water, while the top of the dip is the uppermost point of the trap’s lower portion where the water seals the trap. The vertical distance between these two points gives the depth of the water seal, which is what codes require to be within a certain range to prevent sewer gases from escaping. The other terms describe parts related to how the trap connects or to different flow-control features, not the measurement end used to determine the seal depth.