Backflow Prevention Practice Exam

Which type of backflow preventer is categorized as low-hazard use only?

1. Air-gap separation

2. Atmospheric vacuum breaker

3. Double check valve assembly

4. Pressure vacuum breaker assembly

The correct answer is: Double check valve assembly

The type of backflow preventer that is categorized as low-hazard use only is the atmospheric vacuum breaker. This device is specifically designed to protect against backflow in situations where the potential risk to potable water is minimal. It operates by breaking the vacuum in the piping system when water is withdrawn, thus preventing contaminated water from siphoning back into the clean water supply. In contrast, the double check valve assembly is utilized in medium-hazard situations where there is a potential for non-health hazard pollutants to enter the water system. This type of assembly includes two check valves to prevent backflow, making it suitable for applications that could compromise water quality but don't pose significant health risks. Air-gap separation is a physical separation that provides excellent protection against backflow and is used in high-hazard applications, especially where there is a risk of contamination from direct connections to sewage or hazardous materials. A pressure vacuum breaker assembly, while providing protection against backflow due to negative pressure, is categorized for medium hazard uses and cannot be installed under continuous pressure. Thus, the atmospheric vacuum breaker is specifically designed for low-hazard situations, making it the correct answer for applications where the risk to water supply is minimal.