What must the discharge piping have when it is installed with insert fittings?

The requirement for discharge piping installed with insert fittings to be one nominal size larger is grounded in the need to ensure proper flow and prevent any restrictions that could impact the efficiency of the plumbing system. By increasing the pipe size, the flow capacity is enhanced, which is particularly important in preventing pressure drop and optimizing drainage performance.

Insert fittings can introduce additional potential for turbulence and flow disruption, and using a larger nominal size helps to mitigate these issues. This adjustment accommodates any slight constrictions that may arise from the fittings themselves and ensures that there is sufficient volume for the liquid to travel through without causing backflow or blockages.

Thus, the practice of sizing the discharge piping one nominal size larger when using insert fittings fosters a more reliable and effective plumbing system, aligning with industry standards meant to enhance performance and longevity.