- Backflow Prevention Device
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In the water supply of a building or structure, a backflow prevention device is a type of backflow prevention typically a mechanical device such as a check valve, non-return valve or one-way valve for that is intended to prevent the flow of water in a direction contrary to the normal or intended direction of flow or the unintended flow of water from a potentially polluted source into a drinking water supply.
A backflow prevention device acts as a barrier, ensuring that the drinking water supply remains separate from any potential sources of contamination (such as fire services) within the property.
There are several types of backflow prevention devices available, and the selection of a specific device depends on the level of protection required and the specific application. Here are some common types of backflow prevention devices:
- Atmospheric Vacuum Breaker (AVB): This device is typically used in low-hazard applications and features a check valve that opens to allow water to flow into the property but closes to prevent backflow. It includes an air inlet that opens when there is a drop in pressure, creating a break in the water flow and preventing backflow.
- Pressure Vacuum Breaker (PVB): PVB devices are commonly used in residential and commercial applications. They feature a check valve and an air inlet valve, similar to an AVB. However, a PVB also includes a built-in, spring-loaded air inlet valve that stays closed during normal operation but opens under a drop in pressure, creating a barrier against backflow.
- Double Check Valve Assembly (DCVA): DCVAs are commonly used in medium-hazard applications. They consist of two independently operating check valves, providing an additional layer of protection. These devices also include test cocks for regular testing and verification of their functionality.
- Reduced Pressure Zone (RPZ) Assembly: RPZ assemblies are used in high-hazard applications. They consist of two check valves and a relief valve between them, creating a zone of reduced pressure. The relief valve opens when there is a drop in pressure, preventing backflow and ensuring that any potential contaminants are discharged to a drain.
These are just a few examples of backflow prevention devices, and there may be other types available depending on the specific requirements and regulations in different regions. It's important to consult local plumbing codes and regulations to determine the appropriate type of backflow prevention device for a particular application. Additionally, regular maintenance, testing, and certification of backflow prevention devices are essential to ensure their proper functioning and effectiveness.