How many fixture units can a 2" trap hold?

In the context of the Massachusetts Plumbing Code, a 2-inch trap is typically rated to handle a maximum of 3 fixture units. Fixture units are a measure used to account for the probable demand that plumbing fixtures place on the drainage system. Each type of fixture has an assigned fixture unit value based on how much water it uses and how often it is expected to drain.

The rating of 3 fixture units for a 2-inch trap is based on standard plumbing practices, which take into consideration the capacity of the trap to handle wastewater without upstream pipe blockage or backflow issues.

This means that a 2-inch trap is designed to accommodate several common fixtures, such as a lavatory or sink, within reasonable usage patterns without exceeding its capacity. Therefore, knowing this capacity is essential for proper plumbing design and preventing potential plumbing failures.

In summary, understanding that a 2-inch trap can hold 3 fixture units is critical for ensuring that the drainage system functions efficiently and effectively.