Backflow Prevention Practice Exam

If backpressure builds up at a reduced pressure principle assembly, what is the likely effect on the check valve number 2?

1. Dissipate through the air-vent

2. Push the check valve closed

3. Force the relief valve to open and discharge

4. Remain in the system

The correct answer is: Force the relief valve to open and discharge

When backpressure builds up at a reduced pressure principle assembly, the correct outcome regarding check valve number 2 is that it would lead to the relief valve opening and discharging. The primary purpose of the relief valve in this assembly is to prevent excessive pressure from causing damage or creating unsafe conditions within the system. In a reduced pressure principle assembly, when backpressure occurs, it indicates that the pressure downstream of the assembly is higher than intended and could lead to potential backflow into the potable water supply. To alleviate this situation and protect against contamination, the relief valve is designed to open in response to this increased pressure. By doing so, it allows some of the water to escape from the system, thereby reducing the pressure and allowing normal flow patterns to be restored. The function of the relief valve is critical because if it did not open, the check valves could be forced into an unstable state, potentially leading to a failure in maintaining a proper barrier to backflow. Therefore, the response of the relief valve is an essential safety mechanism in preventing contamination and ensuring the integrity of the water supply system.