What term describes the vertical distance between the crown weir and the top of the dip of a trap?

The term that describes the vertical distance between the crown weir and the top of the dip of a trap is known as the trap seal. This is a crucial concept in plumbing as the trap seal is responsible for preventing sewer gases from entering a building. The trap, which is typically in the form of a U-shaped pipe, holds a specific amount of water, and that water creates a barrier against the gases that may come from the sewer system.

A proper trap seal depth ensures that it can maintain an effective barrier; if the seal were to drop below a certain level, it would no longer provide protection from these gases. This understanding is essential for maintaining plumbing systems and ensuring they function as intended, which is why trap seal is the correct term in this context.

In plumbing terminology, trap depth typically refers to the overall depth measurement of the trap itself, while crown height is not a standard term associated with this particular measurement. Flow distance generally pertains to the path water takes in a plumbing system, which does not specifically relate to the vertical relationship between components of a trap.