When installing a pipe that can carry a maximum of 7,000 DFU at a slope of 1/16 inch per foot, what is the minimum pipe size?

To determine the minimum pipe size for carrying a maximum of 7,000 Drainage Fixture Units (DFU) at a slope of 1/16 inch per foot, it’s essential to understand the flow capacity of different pipe diameters.

In plumbing design, the ability of a pipe to handle a specific DFU load is based on the pipe's diameter and the slope, which affects the velocity of the wastewater flowing through it. A larger diameter pipe allows for more volume and flow capacity compared to a smaller diameter pipe.

Industry standards typically dictate that for a 1/16 inch per foot slope, a 15-inch diameter pipe meets the required capacity for 7,000 DFU based on the anticipated flow rates and hydraulic calculations. This choice balances adequate sizing with the ability to minimize the risk of blockages and ensure effective drainage.

The other options, while larger in diameter, are unnecessary for this specific application, as they exceed the flow requirements for the 7,000 DFU. Over-sizing a pipe can lead to increased costs and may complicate installation without providing added benefits in flow capacity for this specific scenario. Hence, the 15-inch diameter is the appropriate minimum size needed for efficient drainage while remaining cost-effective.