Most pressure type vacuum breakers are installed at what minimum distance above the highest outlet?

• A. 12 inches
• B. 6 inches
• C. 18 inches
• D. 24 inches

Answer: (A)

The key idea is ensuring the vent on a pressure-type vacuum breaker can operate freely to prevent back-siphonage. Keeping the device at a sufficient height above the highest downstream outlet protects the vent from being splashed, wetted, or submerged by irrigation water. When the line pressure drops, the air vent must remain open to admit air and break the siphon; placing the breaker at least twelve inches above the highest outlet provides reliable vertical separation for proper venting and backflow protection. Six inches is often too close and risky, while eighteen or twenty-four inches adds more height than is typically necessary for most installations, though local codes can vary. In standard practice, twelve inches is the minimum that balances safety and practicality.