Types of Backflow Assemblies
Backflow assemblies are devices designed to prevent the reverse flow of water, which can lead to contamination of the potable water supply. There are several types of backflow assemblies commonly used:
Double Check Valve Assembly (DCVA) - This assembly consists of two check valves that allow water to flow in one direction only. It is commonly used in low hazard applications where the risk of contamination is minimal.
Reduced Pressure Zone Assembly (RPZ/RPA) - (Most commonly required by water purveyors) RPZ assemblies provide a higher level of protection than DCVAs. They include two check valves with a relief valve between them. If the pressure between the check valves drops, the relief valve opens, preventing contaminated water from entering the potable water supply.
Pressure Vacuum Breaker (PVB) - (Most commonly required by water purveyors for irrigation) PVB assemblies are typically used in low hazard applications. They include a spring-loaded check valve that closes when water flow stops, and a vent valve that opens to prevent vacuum conditions and backflow.
Atmospheric Vacuum Breaker (AVB) - (Most water purveyors are requiring these to be replaced with a PVB or RPZ/RPA) AVB assemblies are simple devices that prevent backflow by relying on atmospheric pressure. They are commonly used in situations where a continuous supply of water is not required, such as irrigation systems. However, they are not suitable for high hazard applications.
Spill-Resistant Vacuum Breaker (SVB) - SVB assemblies are similar to PVBs but include additional features to prevent spillage of water in case of a malfunction.
Air Gap - An air gap is a physical separation between the potable water supply and potential sources of contamination. It is considered the most effective method of backflow prevention and is often used in high hazard applications.
Each type of backflow assembly has its advantages and is selected based on factors such as the level of hazard, local regulations, and specific application requirements. In the Central Florida area, a majority of the water purveyors are requiring PVB's or RPZ/RPZ's to be installed.