The maximum number of fixture units allowed on a 2 inch waste stack is _____.

In plumbing systems, the concept of fixture units is essential for determining the load that a waste stack can handle. A 2-inch waste stack is designed to accommodate a specific number of fixture units, which are a measure of the probable demand on the plumbing system.

The correct answer, which states that the maximum number of fixture units allowed on a 2-inch waste stack is 16, aligns with the guidelines set forth in the Uniform Plumbing Code (UPC). According to the UPC, a 2-inch waste stack is typically rated for this capacity, ensuring that it can effectively manage the flow of waste while preventing issues such as clogs or backflow.

This value is grounded in the importance of ensuring that the plumbing system can handle the expected volume of waste from the connected fixtures without compromising performance. When too many fixtures are connected beyond this limit, the system risks insufficient drainage, leading to performance issues. Recognizing this limit is crucial for plumbing design and ensuring compliance with the code to maintain a safe and functional plumbing system.

In contrast, the other numerical values provided do not meet the established guidelines for a 2-inch waste stack in the UPC, underscoring the necessity of adhering to the code for reliable plumbing performance.