What is the required backflow protection for a fire sprinkler system containing chemicals?

The required backflow protection for a fire sprinkler system containing chemicals is a reduced pressure zone (RPZ) assembly. RPZ devices are specifically designed to provide a higher level of protection against backflow, which is essential in systems where hazardous substances or chemicals are involved.

In this context, fire sprinkler systems may use chemicals for fire suppression, making it paramount to prevent these harmful substances from contaminating the potable water supply. The RPZ assembly consists of two check valves and a relief valve, which maintains a pressure drop between the two check valves. This design ensures that if a backflow condition occurs, the hazardous chemicals cannot flow back into the water supply, thus providing a reliable barrier against contamination.

Other options like single check valves or double-check valves might not provide adequate protection in situations involving chemical risks, as they are better suited for non-hazardous applications. An air gap, while effective in preventing backflow, may not be practical for a fire sprinkler system, as it often requires significant space and may not maintain the continuous operation of the system. Thus, an RPZ is the appropriate and required choice for any system that handles chemicals, ensuring safety and compliance with regulatory standards.