What is a valve designed to reduce downstream water pressure under both flowing and nonflowing conditions?

The correct choice identifies a valve designed specifically to reduce downstream water pressure under both flowing and non-flowing conditions. This valve is known as a Pressure Reducing Valve. It serves to maintain a stable, lower pressure downstream of the valve, regardless of whether water is moving through the system or not.

This functionality is crucial in fire sprinkler systems, as excessive pressure can lead to system malfunctions or potential damage to the components. By controlling the pressure, a Pressure Reducing Valve ensures that the system operates safely and effectively, allowing it to deliver the necessary flow of water while protecting the fixtures and fittings from high pressure.

While other valves play important roles within a fire sprinkler system, their purposes differ: a Pressure Regulating Valve typically adjusts pressure conditions based on flow demands rather than maintaining a consistent downstream pressure, a Check Valve prevents backflow, and a Control Valve regulates flow and pressure under specific conditions. Thus, the role of the Pressure Reducing Valve stands out in its ability to manage pressure consistently in both states of water flow.