The Principle Operation of an Atmospheric Vacuum Breaker Backflow Prevention Device – Typical Installations
The AVB is used in many plumping installation and incorporated into the plumbing fixtures such as sink faucets. The AVB is designed for low flow installations such as laboratory equipment janitor’s utility sinks, dishwashers, hair washing station sinks and other application that use small amounts of water. The AVB is an end-user backflow prevention device a designed for the isolation of a cross-connection within the plumbing system. The AVB cannot be used on service line for containment protection since it is not designed for backpressure conditions. Although the AVB cannot be tested in-line, it should be inspected periodically. This can be done by opening and closing the upstream shut-off valve and listening for the float disc or poppet to drop down. An internal inspection can be made by removing the canopy or cover and inspecting the float disc to determine if it is moving freely and there is no damage to the sea disc or other internal parts. The inspection of the AVB should include an observation of the AVB air inlet port to ascertain that no rage, towel or other material is impeding the flow of air into the air inlet port. Atmospheric vacuum breakers can only be used on an open-head sprinkler system and where the sprinkler system is not in continuous use for more than 12 continuous hours.
