Cross Connection Practice Exam

Which backflow preventer is permissible where the use of an Approved Air Gap is impractical?

1. Atmospheric Vacuum Breaker

2. Reduced Pressure Principle Backflow Assembly

3. Single Check Valve

4. Belt Filter Press

The correct answer is: Reduced Pressure Principle Backflow Assembly

The Reduced Pressure Principle Backflow Assembly is recognized as an appropriate alternative when an approved air gap is not feasible. This type of backflow preventer is designed to protect potable water supplies from contamination due to backflow by maintaining a continuous air gap under atmospheric pressure. The Reduced Pressure Principle assembly includes two independently acting check valves and a pressure differential relief valve, which allows it to effectively mitigate the risk of backflow. In situations where an air gap cannot be established due to space constraints or other practicalities, using a Reduced Pressure Principle Assembly provides a robust protection level against the potential hazards of backflow. This makes it suitable for locations where a direct air gap cannot be practically constructed while still ensuring the safety of the water supply. The other options do not provide adequate protection in similar scenarios: Atmospheric Vacuum Breakers are not suitable for situations under continuous pressure; a Single Check Valve may not adequately prevent backflow in all circumstances, as it lacks the redundancy and protection features of the Reduced Pressure assembly; and a Belt Filter Press is an equipment type used in wastewater treatment, not a backflow preventer, and therefore not applicable in this context. This solidifies the Reduced Pressure Principle Backflow Assembly as the appropriate choice.