A fixture trap shall have a water seal not less than 2 inches nor more than what measurement?

The water seal in a fixture trap is crucial for preventing the escape of sewer gases into occupied spaces. In plumbing codes, a fixture trap's water seal is specified to ensure it is effective. The requirement stipulates that the water seal must not be less than 2 inches and cannot exceed 4 inches. This range is designed to ensure that the trap remains functional while preventing issues such as siphoning or evaporation that could compromise the seal.

Thus, the maximum water seal measurement of 4 inches is the correct value as it aligns with plumbing standards, which are established to maintain health and safety in plumbing systems. A water seal exceeding this measurement could lead to insufficient trap efficiency, whereas a seal below the minimum may not provide adequate protection against harmful gases. The regulation reflects a balance between function and practicality, ensuring both safety and performance in plumbing installations.