Pressure-restricting devices (PRD) have which function?

Pressure-restricting devices (PRD) have which function?

• A. Increase pressure during pumping
• B. Have no effect on pressure
• C. Limit pressure only when water is flowing
• D. Limit pressure during static conditions

Answer: (C)

Pressure-restricting devices limit the pressure in a sprinkler/standpipe system when water is moving, preventing damaging pressure spikes as flow occurs. They sit relatively idle with no flow, but once pumping or other demand starts, they throttle the downstream pressure to a safe, set level. This protects piping, fittings, valves, and sprinkler heads from excessive pressure during operation. They do not raise pressure, and they aren’t meant to regulate static pressure when nothing is flowing, which is why the correct description is that they limit pressure only when water is flowing.

Pressure-restricting devices limit the pressure in a sprinkler/standpipe system when water is moving, preventing damaging pressure spikes as flow occurs. They sit relatively idle with no flow, but once pumping or other demand starts, they throttle the downstream pressure to a safe, set level. This protects piping, fittings, valves, and sprinkler heads from excessive pressure during operation. They do not raise pressure, and they aren’t meant to regulate static pressure when nothing is flowing, which is why the correct description is that they limit pressure only when water is flowing.