A. Spring loaded means it has a spring. It tends to seal better (best for potable water pumps), but the spring will wear out easier and does take more pressure to open it. A swing check works on the gravity principle (more reliable in the long run), and it take less pressure to open it, minimizing pressure loss (best for sump, pond, fountain, sewage pumps). A swing check can be used for horizontal or vertical mounting for fluid flowing upward. However, swing check valves are not recommended for applications where frequent reversal of water flow occurs as this can cause the valve (swing disk) to fluctuate rapidly resulting in valve chatter or water hammer noise. Spring check valves are better suited for this type of application and may also be installed horizontally or vertically with upward fluid flow.