What type of device prevents the backflow of the spray mixture into the water system?

The device that prevents the backflow of the spray mixture into the water system is known as a backflow preventer. This device is critical in maintaining the safety of water systems by stopping any contaminated water from flowing back into the clean water supply. In agricultural and pest management contexts, backflow preventers are particularly important when chemical mixtures are used for spraying.

When a spray mixture is applied, there is a potential risk that pressure changes could cause the liquid to siphon back into the water supply. The backflow preventer ensures that this does not happen by creating a one-way flow system, allowing water to move in only one direction—away from the water source and preventing any contaminants from entering the clean water supply.

The other devices listed serve different purposes. For example, a pressure regulator helps manage the pressure of the spray mixture but does not prevent backflow. A flow meter measures the volume of liquid being used but does not address backflow issues. Lastly, a filter screen is designed to filter out particulate matter but does not prevent the reverse flow of liquids. Each of these devices plays an important role in the overall system, but it is the backflow preventer that specifically addresses the risk of contamination through reverse flow.