The Principle Operation of a Hose Bibb Vacuum Breaker Backflow Prevention Device – General Specifications
The hose bibb vacuum breaker (HBVB) is a backflow prevention device that is attached to a sill cock to prevent the backsiphonage of non-potable water into the potable water system. The HBVB consists of a single spring loaded check valve and an atmospheric vent that is sealed closed by a diaphragm during a flow condition. The check valve is force loaded to a closed position and the atmospheric vent is forced loaded to an open position. Anti-Freeze HBVB are available that are equipped with automatic drain for protection against freezing when the hose is removed. The HBVB shall comply with ASSE Standard 1011.
Some HBVB are equipped with tamper proof versions such as break-away set screws to prevent the removal of the HBVB from the sill cock. Other are equipped with special threads for permanent installations. Some HBVB are built into the fixture.