What is a key difference between air gaps and check valves?

Air gaps and check valves serve distinct purposes in backflow prevention, and understanding their differences is essential for effective application. An air gap is a physical separation between the water supply and any potential source of contamination, providing a reliable barrier that requires no mechanical parts to function. This lack of moving components means that air gaps are largely maintenance-free; they do not degrade or fail over time like mechanical devices can.

In contrast, check valves contain moving parts that allow water to flow in one direction while preventing backflow. These components can be susceptible to wear and tear, leading to potential failure under certain conditions, such as pressure changes or mechanical stress. Thus, while check valves can be effective in preventing backflow, they typically require periodic inspection and maintenance to ensure their reliability.

The effectiveness of air gaps isn't primarily influenced by pressure; they function based solely on gravity and the physical separation of fluids, thus making them more resilient to various pressure conditions compared to check valves. Therefore, the assertion that air gaps require no maintenance accurately highlights a fundamental difference, underscoring the inherent reliability of this method in backflow prevention systems.