The Principle Operation of a Hose Bibb Vacuum Breaker Backflow Prevention Device – Installation
HBVB are designed to prevent backsiphonage only and should not be used where backpressure is present. The HBVB is designed to be installed on the discharge side of the hose bibb, hydrant or faucet that is fitted with hose threads. The HBVB is approved for use to control high hazard cross-connections. The HBVB shall not be installed below grade where it may become submerged in water or installed where it may freeze when a hose is attached and subjected to low head pressure. The outlet of the HBVB shall remain open to the atmosphere. Valves shall not be installed downstream of the HBVB where the inlet pressure will be constant for twelve hours or more. A piping opening or outlet with a hose connection or where a hose can be connected shall be equipped with a permanent or locking HBVB. The HBVB may be subjected to low head backpressure not greater than 4.33 psi.