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When close to two intersecting walls, an air-gap separation is increased from 2 diameters to _____ diameters?

  1. 2.5

  2. 3

  3. 3.5

  4. 4

The correct answer is: 4

In backflow prevention, the concept of an air gap is crucial for ensuring that potentially contaminated water cannot flow back into the potable water supply. The air gap is the vertical distance between the highest point of a water supply outlet and the lowest point of any potential backflow source. When it comes to maintaining effective air gaps, particularly in configurations close to intersecting walls, the distance must be adjusted to prevent the risk of backflow. The increase of the air-gap separation from 2 diameters to 4 diameters reflects a recommendation based on the principle of maintaining an adequate buffer zone between the water supply and any contaminants. This adjustment is particularly important in enclosed spaces, as walls can disrupt the free flow of air and create conditions that may facilitate backflow. Increasing the air gap to 4 diameters provides an added level of safety, accounting for factors such as turbulence, potential siphoning effects, and variations in pressure that could arise from nearby plumbing configurations. By adhering to this more stringent guideline, the risk of cross-contamination is minimized, thus ensuring the integrity of the potable water system.