What does the "C" factor of a pipe refer to?

The "C" factor, also known as the Hazen-Williams coefficient, refers to the smoothness of the interior surface of a pipe. This factor is critical in hydraulic calculations for water flow within pipes because it directly influences the friction loss. A higher "C" value indicates a smoother pipe, which means there is less resistance to flow and therefore lower friction losses. Smooth materials allow water to flow more easily compared to rough materials, which create turbulence and increase resistance.

The other options do not accurately describe the "C" factor. The diameter of the pipe is essential for calculating flow, but it is not what the "C" factor represents. Age of the pipe can affect its condition and smoothness over time but is not factored in as the "C" value. Length is also an important consideration in flow calculations, but it is not relevant to the "C" factor. Thus, the focus on the smoothness aspect clarifies the importance of the "C" factor in determining fluid dynamics in pipe systems.