Which type of vacuum breaker is pressure activated?

The type of vacuum breaker that is pressure activated is the anti siphon vacuum breaker (pressure type). This device operates by utilizing the pressure of the water flow to create a seal that prevents the backflow of water into the potable water supply.

When water flow is present, the pressure type vacuum breaker remains in its closed position, preventing any potential siphoning action that could occur if a backflow situation arises. This mechanism is particularly important in plumbing systems to protect against contamination from non-potable sources. The pressure activation ensures that the vacuum breaker functions effectively during periods of normal water flow, making it a critical component in maintaining a safe and compliant plumbing system.

In contrast, the non-pressure type relies on gravity and atmospheric pressure, which does not engage the same level of protection during pressure changes in the plumbing system. Atmospheric vacuum breakers do not use pressure to operate and can only function if there is no pressure present in the supply line, while a double check valve is specifically meant for preventing backflow but operates on a different premise than a vacuum breaker.