What is the primary function of a vacuum breaker in plumbing?

The primary function of a vacuum breaker in plumbing is to prevent back-siphoning of contaminated liquids. This device is crucial in situations where a potential cross-connection exists between potable water supplies and non-potable sources. By allowing air to enter the system when a negative pressure occurs, the vacuum breaker stops the vacuum from creating a suction that could draw contaminated water back into the clean water supply. This is particularly important in maintaining the safety and integrity of drinking water systems, ensuring that harmful substances do not compromise public health.

In contrast, the other options relate to functions that a vacuum breaker does not perform. For example, regulating gas pressure is a function of pressure regulators, while enhancing water flow could be associated with different plumbing fixtures or systems designed to increase efficiency. Filtering solid particles pertains to strainers or filters designed specifically for removing debris, which is not the role of a vacuum breaker. Thus, the focus of a vacuum breaker's design and operation revolves strictly around preventing contamination, highlighting its essential role in plumbing safety.