WC Series wafer check valves are offered in PVC, PP and PVDF. O-ring material is FPM, EPDM or PTFE encapsulated FPM. Sizes 10in. through 20in. are supplied with a spacer in PVC and PP materials only. Spacers are not required for DIN or PVDF pipe installations. Spacers allow full disk opening and are required when using Schedule 80 pipe. Wafer checks can be ordered with a spring as an option. Spring materials are stainless steel or Hastelloy®. Are standard but can be special ordered up to 40 in.