Backflow Prevention Practice Exam

What may cause intermittent relief valve discharge from a reduced pressure principle assembly?

1. A fouled check valve number 1

2. A fouled check valve number 2

3. A fouled relief valve

4. Water hammer or hydraulic shock

The correct answer is: Water hammer or hydraulic shock

Intermittent relief valve discharge from a reduced pressure principle assembly can occur due to water hammer or hydraulic shock. These phenomena are characterized by sudden changes in pressure within the piping system, often resulting from quick changes in fluid flow or valve operation. When this unexpected pressure spike occurs, it can force the relief valve to open briefly, allowing fluid to discharge. This intermittent discharge is a response to the pressure fluctuations rather than a failure in the system components. In contrast, fouled check valves may lead to continuous or more severe malfunctions within the assembly, but they typically do not cause intermittent discharges. A fouled check valve could lead to backflow or failure of the assembly to maintain pressure, but it would be less likely to result in short, intermittent releases of pressure. Similarly, a fouled relief valve would more commonly stick or fail to open or close properly rather than exhibit intermittent discharge. Therefore, the dynamics of water hammer or hydraulic shock present a clear connection to the observed symptom of intermittent relief valve discharge.