What is the purpose of a pressure vacuum breaker?

The purpose of a pressure vacuum breaker is fundamentally to prevent siphoning in a piping system. Siphoning can occur when there is a significant difference in pressure between two points in a system, which can lead to the backflow of fluids potentially contaminated or unwanted into a clean water supply. The pressure vacuum breaker operates by allowing air to enter the system when a negative pressure (vacuum) is detected, breaking the siphon effect and preventing the reverse flow of potentially hazardous materials.

This mechanism is crucial in systems where fluids are conveyed under pressure and must be protected from contamination. By introducing air into the system when needed, the pressure vacuum breaker effectively interrupts the siphoning effect before it can lead to backflow issues, ensuring the integrity and safety of the water supply.