An approved device used to prevent backflow and backsiphonage is a...

A vacuum breaker is an approved device specifically designed to prevent backflow and backsiphonage in plumbing systems. It functions by introducing air into the piping system when a vacuum is created, which helps to interrupt the flow of water in the reverse direction. This mechanism effectively protects the water supply from contamination that could occur if there were a negative pressure or backflow situation.

The importance of using a vacuum breaker lies in its ability to shield potable water supplies from potential hazards, ensuring safe drinking water. It is often found in various applications, including irrigation systems and fixtures where the potential for backsiphonage exists.

While check valves are also used to prevent backflow, they operate differently, allowing water to flow in one direction without the same level of protection from vacuum conditions. Therefore, for preventing both backflow and backsiphonage specifically, the vacuum breaker is the appropriate device.