When using a pressure reducing and pressure sustaining valve together, what does one valve maintain?

When using a pressure reducing valve in conjunction with a pressure sustaining valve, the pressure sustaining valve is responsible for maintaining a constant downstream pressure. This configuration allows for the regulation of water pressure within a specific system, ensuring that the pressure delivered to end users remains stable and does not fluctuate significantly.

The pressure reducing valve functions to lower and maintain the upstream pressure to a desired setpoint, which can then be sustained by the pressure sustaining valve downstream. This mechanism is crucial in water distribution systems where varying demands and fluctuating upstream pressures can lead to inconsistent service pressures at the consumer's end. By stabilizing the downstream pressure, the system can effectively prevent issues such as water hammer, leaks, or inconsistent flow rates, which can arise from pressure variations.