What component is crucial for the operation of a pressure vacuum breaker?

The operation of a pressure vacuum breaker relies heavily on the presence of a relief valve. The relief valve is designed to open in order to relieve pressure when a backflow condition occurs. This is essential because it helps to prevent a vacuum from forming in the system, which could otherwise lead to the siphoning of contaminated water into the potable water supply.

When water is flowing normally, the pressure in the system keeps the relief valve closed. However, if there is a sudden drop in pressure (such as when a nearby hydrant is opened), the relief valve automatically opens to allow air to enter the system. This action breaks the siphon effect and prevents backflow, ensuring that any potential contaminants remain isolated from the clean water supply.

Therefore, the relief valve is a key component in ensuring the safety and proper function of the pressure vacuum breaker. Understanding its role helps in recognizing how backflow prevention devices maintain the integrity of potable water systems.