What is a Double check valve assembly?

A double check valve assembly is indeed a type of backflow prevention device. It is designed to protect the water supply from contamination due to backflow, which can occur when there is a decrease in the pressure of the potable water supply, allowing potentially contaminated water to flow back into the clean water system.

This assembly consists of two check valves that operate independently, creating a physical barrier to prevent backflow. In the event that one valve fails, the second valve acts as a backup, ensuring that any contaminants cannot enter the potable water system. This is critically important in maintaining the safety and quality of drinking water, and it is widely used in various applications, including commercial and industrial settings, where there's a risk of cross-connection between potable water and non-potable sources.

In contrast, the other options provided do not accurately describe a double check valve assembly. It is neither a treatment unit nor a filtration mechanism, which focus on purifying water rather than preventing contamination through backflow. Additionally, it does not measure water pressure, as its primary function is solely related to backflow prevention.