What is the DFU value for a 3-inch trap?

The Drainage Fixture Unit (DFU) value for a 3-inch trap is 5. DFU values are used to calculate the load on a plumbing system and determine the required size of the drainage piping. The DFU value assigned to various plumbing fixtures helps in understanding how much drainage capacity is needed to adequately handle the waste produced by those fixtures.

A 3-inch trap has a higher DFU value compared to smaller traps (such as those with a 2-inch or 1.5-inch trap) because it can accommodate a larger volume of waste and allow for greater flow rates. This means it is effectively suited for fixtures that have a higher drainage demand, which is often the case in commercial settings or for multiple fixtures draining into one line.

The values for smaller traps represent lower capacities and therefore lower DFU values, which reflects their use in less demanding drainage scenarios. Understanding these values is crucial for ensuring that the plumbing system is designed to handle the expected load without risking blockages or inadequate drainage.