Double-door check valves, also known as dual disc check valves, consist of two quick-closing, spring-loaded discs in one body that produce minimal pressure fluctuations within the system when they close. They have inline inlet and outlet ports that ensure efficient flow and induce minimal head loss. These valves ensure media travels through a system in the intended direction and prevent backflow. Flowing media on the inlet side swing the discs away from the seat, opening the valve. When inlet pressure drops below outlet pressure, the discs will swing closed to prevent backflow and contamination.