The check valves type 561 and 562 have been redesigned and complement the GFPS line of plastic valves. The standard cone check valve type 561 seals with medium pressure (water column). The type 562 is equipped with a spring, closes autonomously and can be installed in any position. The valves rely on a specially developed double-guided cone. Its geometry is designed for optimal flow and minimal pressure loss, thus significantly improving valve efficiency and performance. The 562 check valve closes absolutely leak-tight with the built-in spring – even without a water column. In this way, it can be installed in any position, whether horizontally or vertically. A selection of various materials are available for the spring, either stainless steel (DIN standard material no. 1.4310), plastic (ECTFE) encased Nimonic 90 ® (2.4632) or high quality Nimonic 90 ® (2.4632). The Nimonic spring is recommended for applications with aggressive chemicals. The guided cone is subjected to less wear and tear, reducing maintenance to a minimum and increasing the service life. Additionally, the noise generated at high flow velocities has been drastically reduced. Taking into account the larger flow volumes in piping system construction today, the dimension range has been extended in all materials to include DN65, DN80 and DN100. The valves in PVC-U, PVC-C, ABS, PP-H and PVDF are available in dimensions DN10-DN100. The wide assortment of connecting parts in all the conventional standards and versions means that the valves can be built into plastic piping systems worldwide, whether ISO, ANSI or JIS standard.