Cross Connection Practice Exam

The relief valve of a Reduced Pressure Principle Backflow assembly discharges in a static condition. The most likely cause for it to stop discharging during a flow condition is:

1. Dirt in the valve

2. Fouled number one check valve

3. Excessive pressure

4. Insufficient water flow

The correct answer is: Fouled number one check valve

The relief valve of a Reduced Pressure Principle Backflow assembly is designed to discharge water whenever there is a difference in pressure that indicates a potential backflow condition. When the system is in a static condition, usually the pressure is stable, allowing the relief valve to function normally and discharge. However, during a flow condition, if the first check valve becomes fouled or compromised, it acts as a barrier preventing water from flowing freely through the system. This fouling can create a situation where the pressure differential required to keep the relief valve open is not maintained. As a result, even though the pressure in the assembly may suggest a backflow risk, the inability of water to flow freely due to the fouled check valve can prevent the relief valve from discharging, effectively creating a condition where it is unable to operate as intended. Therefore, a fouled first check valve directly impacts the flow and pressure dynamics essential for the relief valve's operation, making this the most likely cause for the relief valve to stop discharging during flow conditions.