What is a Duo Check Valve?
A duo check is a spring-loaded dual plate check valve that is designed to allow the flow in one direction and prevent it from reversing and flowing in the reverse direction. These valves are often used in industrial, commercial, residential, oil and gas, water treatment, and chemical processing. Like a swing check, duo check discs are hinged and open with the flow of media through the valve. Unlike a swing check the discs are spring-loaded and begin to close before the flow is reversed. Additionally, the two discs offer quicker closing since each of the discs has less distance to travel from fully open to closed compared to a swing check. The main advantage is quick closing of the valve reduces the chance of water hammer and backflow. The main disadvantages are the increased pressure drop because of the disc and the hinges being in the flow path and a slightly higher cracking pressure.