Which of the following is NOT a type of backflow prevention device?

The pressure relief valve is not classified as a backflow prevention device. Backflow prevention devices are specifically designed to prevent the reverse flow of contaminated water into the potable water supply, ensuring that drinking water remains safe from potential contaminants.

On the other hand, an atmospheric vacuum breaker, a reduced pressure principle assembly, and a double check valve assembly are all recognized types of backflow prevention devices.

The atmospheric vacuum breaker works by preventing back siphonage by creating an air gap when there is a drop in water pressure. The reduced pressure principle assembly utilizes two check valves and a pressure differential relief valve to maintain a lower pressure in the inner chamber, which prevents contaminants from flowing back into the clean water supply. Similarly, a double check valve assembly contains two check valves that operate independently to prevent backflow.

In contrast, a pressure relief valve is used primarily for protecting against excessive pressure within a system, rather than preventing backflow. Its function is to release pressure when it exceeds a specified limit, making it essential for maintaining system safety, but not for preventing contamination of the water supply.