Water Distribution Grade 1 Certification Practice Exam

What is a main difference between a reduced pressure principle backflow device and a double check backflow device?

1. Relief Valve

2. Ball Valve

3. Spring Valve

4. Isolation Valve

The correct answer is: Relief Valve

The main distinction between a reduced pressure principle backflow device and a double check backflow device lies in the presence of a relief valve. A reduced pressure principle backflow device incorporates a relief valve that allows for the discharge of water if the pressure in the system drops below a specified level. This mechanism is critical for protecting the potable water supply from potential backflow situations that could introduce contaminants into the drinking water system. The relief valve functions by ensuring that any back pressure or back siphonage situation can be safely relieved, thus maintaining a barrier to prevent the reverse flow of contaminated water. This makes reduced pressure principle devices particularly suitable in high hazard scenarios where the risk of contamination is greater. In contrast, a double check backflow device does not contain a relief valve. Instead, it relies on two check valves that prevent backflow but do not address the situation of a pressure drop effectively. Thus, in applications where there is a risk of contamination from backflow, the inclusion of the relief valve in reduced pressure devices makes them more suitable than their double check counterparts, emphasizing the importance of this feature.