Can a double check backflow device be used on a system containing antifreeze?

The correct response is that a double check backflow device should never be used on a system containing antifreeze. A double check valve assembly is designed to protect against backflow caused by backpressure and backsiphonage in non-health hazard applications. However, antifreeze in a system could affect the performance of the double check assembly, particularly in terms of flow characteristics and sealing capabilities.

When antifreeze is present, it can create a risk of improper functioning or even failure of the device due to the variations in specific gravity and viscosity compared to water. Furthermore, the use of antifreeze may involve chemicals that could compromise the materials used in the backflow preventer, potentially leading to leaks and allowing contaminants to enter the potable water supply.

Therefore, it's imperative to use appropriate backflow prevention devices specifically rated for systems with antifreeze to ensure safety and compliance with plumbing codes and regulations.