A vacuum breaker is a device that is installed in a plumbing system to prevent backflow. Backflow is the undesirable reversal of flow of water or other liquids in a piping system. This can happen when there is a decrease in pressure in the system, such as when a fire hydrant is used or when power is lost to the pumps that move water through the pipes. Vacuum breakers are designed to open and release any built up pressure so that backflow does not occur.
There are two types of vacuum breakers: atmospheric and pressure type. Atmospheric vacuum breakers are installed on the highest point of a piping system, and they rely on gravity to function. Pressure type vacuum breakers are installed inline and use a spring-loaded check valve to open and close.
Atmospheric vacuum breakers are typically used for irrigation systems, while pressure type vacuum breakers are used for pressurized systems, such as those found in commercial buildings. Both types of devices should be tested regularly to ensure they are working properly.