Backflow Prevention Practice Exam

What is the primary function of an atmospheric vacuum breaker?

1. To maintain pressure

2. To prevent backpressure

3. To prevent backsiphonage

4. To control water flow

The correct answer is: To prevent backsiphonage

The primary function of an atmospheric vacuum breaker is to prevent backsiphonage, which occurs when a drop in water pressure creates a vacuum that draws contaminated water back into a potable water supply. This device is designed to break the vacuum when negative pressure occurs, thereby allowing air to enter the system and stop the backward flow of potentially harmful liquids. By having an opening exposed to the atmosphere, the atmospheric vacuum breaker ensures that air can enter the system, preventing conditions conducive to backsiphonage. It is often installed in situations where water might be siphoned back into a potable water supply, protecting public health and maintaining the integrity of the drinking water system. While maintaining pressure and preventing backpressure are important in various plumbing applications, those functions are not within the primary scope of an atmospheric vacuum breaker. Similarly, controlling water flow isn’t a direct function of this device, as its focus is specifically on preventing the reversal of flow due to pressure changes.