Atmospheric Vacuum Breaker (AVB) is a backflow prevention device that protects against backsiphonage. AVB placement must always be placed downstream of all shut of valves (anything that can start or stop the flow of water) and installed at least 6 inches above all downstream piping and outlets. Manufacturer design limitations do not allow this valve to operate more than 12-hours in a 24-hour period. This device does not require annual testing.

Pressure Vacuum Breaker (PVB) is a backflow prevention device that protects against backsiphonage. PVB placement must be at least 12 inches above all downstream piping and outlets but may have shut off valves installed downstream. Manufacturer design allows for continuous use in a 24-period. Annual testing is required.

Air Gap (AG) is a physical separation of the supply pipe by at least two times the diameter of the discharge pipe but never less than 1 inch vertically above the rim of the receiving vessel. This is the highest level of backflow protection.

Reduced Pressure Zone Assembly (RPZ) is a backflow prevention device that protects against both backsiphonage and backpressure. RPZ placement must be between 12 and 36 inches above grade. Installation must allow for convenient accessibility for testing and repair. Annual testing is required.

Double Check Valve Assembly (DCVA) is a backflow preventer valve that protects against both backsiphonage and backpressure for pollutants only. DCVA placement must be between 12 and 36 inches above grade. Installation must allow for accessibility for testing and repair. Annual testing is required.