Which type of check valve is recommended for pump discharge lines from sump or ejector basins?

A spring-loaded or weight-loaded check valve is the most suitable choice for pump discharge lines from sump or ejector basins due to its reliable operation under varying flow conditions. This type of check valve is designed to prevent backflow in the system, ensuring that water only moves in one direction—from the sump or ejector basin to the discharge line.

Spring-loaded check valves are effective because they automatically close when the pump stops or if there is a backflow situation, thereby preventing any potential overflow or flooding in the basin. The spring mechanism provides a quick, positive closure when the water flow decreases, promoting system safety and efficiency.

In contrast, flapper valves may not respond as quickly or reliably under all circumstances, particularly in systems with fluctuating flow rates. Cock valves are generally used for on-off control of flow but do not provide the backflow prevention that is essential in these applications. Ball valves are also used for shut-off purposes and not designed specifically for preventing backflow.

Thus, a spring-loaded or weight-loaded check valve is the most effective and recommended solution for ensuring proper drainage and protection of pump systems from backflow in sump and ejector applications.