Which devices are specific for preventing irrigation backflows?

The correct choice identifies pressure vacuum breakers and atmospheric vacuum breakers as specific devices for preventing irrigation backflows. These devices are particularly designed to protect the water supply from contamination due to backflow caused by a drop in system pressure, which can occur during irrigation processes.

Pressure vacuum breakers are installed to prevent water from siphoning back into the distribution system. They include a spring-loaded check valve that automatically closes when system pressure drops, thus stopping any potential pollution from entering the clean water supply.

Atmospheric vacuum breakers also serve a similar purpose but operate differently by allowing air to enter the system when the pressure drops, preventing siphoning. They are placed at specific points in the irrigation system to provide protection against backflow.

Both device types are crucial in agricultural and landscape irrigation scenarios, where there is a risk of contaminants being drawn back into the potable water supply during certain conditions. Their design and functionality make them specifically suited for controlling backflow in irrigation systems, distinguishing them from the other options provided.