Cross Connection Practice Exam

A marine facility uses a Reduced Pressure Principle Backflow Assembly for premise isolation. What is the minimum level of additional protection on the water service at each pierhead outlet?

1. Reduced Pressure Principle Backflow Assembly

2. Air Gap

3. Double Check Valve Assembly

4. Single Check Valve

The correct answer is: Double Check Valve Assembly

In a marine facility, the use of a Reduced Pressure Principle Backflow Assembly (RPBA) for premise isolation offers significant protection against backflow, particularly where the risk of contamination from water being discharged back into the potable water system is high. To enhance safety, particularly at specific outlets like pierhead outlets, additional protection measures are often needed. The minimum additional protection required at each pierhead outlet is typically a Double Check Valve Assembly (DCVA). This assembly provides a secondary layer of defense against backflow, effectively ensuring that even if there is a malfunction in the RPBA or the system experiences changes in pressure, the risk of potential contaminants entering the drinking water supply remains minimized. Unlike other options, such as a Single Check Valve, which only provides basic backflow prevention, the Double Check Valve Assembly is designed to handle situations with higher hazards by containing two independent check mechanisms. This redundancy ensures that there is an additional safeguard against backflow scenarios that could compromise water quality and safety. While an Air Gap is a highly effective method of preventing contamination, it may not be practical for all applications, particularly in a marine setting where outlet designs could be constrained. The RPBA itself is already in place and serves as a primary isolation point. The continued use of