Backflow Prevention Practice Exam

Flow from the outlet of an atmospheric vacuum breaker should not reach which of the following?

1. Closed tank

2. Section of straight tubing

3. Submerged inlet

4. Toxic substance

The correct answer is: Submerged inlet

The correct answer highlights that flow from the outlet of an atmospheric vacuum breaker should not reach a submerged inlet. This is crucial because an atmospheric vacuum breaker is designed to prevent backflow, specifically protecting the potable water supply from contamination. If the outlet were to discharge into a submerged inlet, it creates the potential for backflow to occur, allowing contaminants from the submerged inlet to enter the clean water supply. Submerged inlets are particularly dangerous as they are often connected to sources that could contain contaminants: for example, bodies of water, waste systems, or industrial processes. When the water level rises at the point of the submerged inlet, it can lead to siphoning action, drawing dirty water back into the clean supply, compromising its safety and making it crucial to ensure that connections to a vacuum breaker are kept above all potential flood levels. The other options do not pose the same risk since flow from the atmospheric vacuum breaker can reach a closed tank or a section of straight tubing without significant risk of backflow occurring, as long as proper devices are utilized to maintain separation and pressure dynamics. Similarly, while flow should be managed around toxic substances, they do not directly relate to the mechanics of an atmospheric vacuum breaker as strongly as the issue related to submerged inlets