What is a reduced pressure zone device primarily used for?

A reduced pressure zone device is primarily used for backflow prevention in cross connections, which is critical for maintaining the safety and quality of the drinking water supply. In situations where there is a risk of contaminated water flowing back into the potable water system, a reduced pressure zone device acts as a safeguard. It typically consists of two independent check valves along with a pressure relieve valve that maintains a lower pressure in the zone between the check valves than that of the surrounding system. This pressure differential prevents any backflow of potentially contaminated water into the clean water supply, ensuring public health and compliance with public water regulations.

The other options are not related to the primary function of a reduced pressure zone device, as it does not pertain to heating systems, water filtration systems, or chemical injection systems. Each of those systems has its own specific mechanisms and equipment designed for their respective purposes.