What does a pressure vacuum breaker do?

A pressure vacuum breaker is a crucial component in irrigation systems designed specifically to prevent backflow, which is the reverse flow of contaminated water into the clean water supply. It achieves this by using a mechanism that opens to allow air into the system if a drop in pressure occurs, thus breaking the vacuum that could cause siphoning of water back into the potable water source. This function is vital in protecting the drinking water supply from contaminants that can be drawn into the system during conditions of high demand or pressure loss.

The other options do not accurately describe the main function of a pressure vacuum breaker. For example, it does not have a role in increasing water pressure or measuring flow rates, nor does it affect the size of piping required in the system. Instead, its sole purpose focuses on ensuring water safety by preventing pollution through backflow. Understanding the role of a pressure vacuum breaker is essential for anyone involved in irrigation system design and maintenance, as it directly impacts the integrity of the water supply.