Which device is used to prevent backflow and control cross connections?

The double check valve is a critical device in plumbing and fluid systems that is specifically designed to prevent backflow and control cross connections between different systems. It operates using two independently acting check valves. This construction ensures that if one valve fails, the other valve will still provide protection against reverse flow, thus safeguarding potable water supplies from contamination due to backflow.

When water pressure drops in a system, there is a risk of non-potable water flowing back into the clean water supply. The double check valve effectively eliminates this risk by only allowing water to flow in one direction. Its installation is common in various applications where cross-connection risks are present, such as irrigation systems or where hoses might connect with potentially contaminated water sources.

In contrast, a pressure regulator serves to manage the pressure of water entering a system, and a flow restrictor limits flow rate but does not inherently prevent backflow. The thermostatic mixing valve adjusts the temperature of water by blending hot and cold supplies, but it does not control backflow. Thus, the double check valve is uniquely suited for the role of preventing backflow and controlling cross connections.