Swing Check Valve -> Swing Check Valve Swing check valves are the most common and best check valve for general-purpose use. Of all check valve designs, these valves produce the lowest pressure drop, when compared with other check valves of the same size. They feature a simple design that is easy to maintain. The swing check valve functions by allowing flow forces to move the disc from the closed position to the fully open position in a sweeping arc motion against the hinge-stop inside of the valve body. Due to the weight and center-of-gravity location of the disc and swing-arm assembly, the valve will return to the closed position should flow become interrupted or reversed. External counterweights mounted on the hinge pin are sometimes used to increase or decrease the reaction time and speed of the disc returning to the closed position. Seating surfaces are typically flat, which means the radial disc positioning onto the seat is not critical, except that it must be flat onto t…