A back flow valve installed in a manhole more than 2 feet deep requires the diameter of the manhole to be at least how many inches?

In plumbing and drainage systems, the size of the manhole is critical to ensure proper access for maintenance and functionality of components such as a backflow valve. For a backflow valve installed in a manhole that is more than 2 feet deep, a manhole diameter of at least 48 inches is required.

This dimension is established to facilitate adequate working space around the valve, allowing for safe inspection, maintenance, and potential repair without risk of injury or obstruction. The 48-inch diameter accommodates the necessary clearance for personnel to maneuver comfortably while ensuring that tool access is sufficient to conduct tasks efficiently.

Smaller diameters, while possibly sufficient for some applications, would not provide the optimal working space needed for handling larger equipment or for addressing issues that may arise with the backflow prevention system. Thus, the choice of 48 inches is consistent with best practices for safety and effective maintenance in plumbing systems.