What is the primary purpose of using a spring-loaded check valve in discharge lines?

A spring-loaded check valve is designed specifically to prevent backflow in discharge lines, which is essential in maintaining the integrity of a plumbing system. When water is pumped through a discharge line, the valve allows flow in one direction when the pressure from the pump is sufficient to open it. If the pressure decreases or if there is a reverse flow, the spring mechanism closes the valve, preventing backflow.

This feature is crucial for various reasons: it protects pumps and other equipment from potential damage that could result from backflow; it helps maintain system pressure; and it prevents contamination of the fresh water supply. Understanding the role of this check valve is important for ensuring that discharge lines operate effectively and safely. The other choices, while related to plumbing systems, do not accurately describe the primary function of a spring-loaded check valve.