What effect does a flow-control valve have when fully closed?

When a flow-control valve is fully closed, it effectively stops water movement entirely. This is because the valve creates a physical barrier that restricts the passage of water through the valve, preventing any flow. In irrigation systems, this function is crucial for controlling water distribution. By closing the valve, technicians can isolate parts of the system for maintenance or repairs without affecting the entire system, ensuring that water does not continue to flow into the isolated area.

This action does not merely reduce flow or pressure; it completely halts the flow of water, demonstrating the valve's role in managing water within the irrigation system. In contrast, a flow-control valve that is partially opened might only reduce flow or pressure but would not completely stop it.