Check Valves : PW Series Wafer Check
The Chemline PW Series Wafer Check Valve offers high end features at reasonable cost. This wafer check does not require a separate spacer or flange gaskets. The large orifice and full flow design means low pressure drop. Spring assisted disc closure is standard as well as an optical indication of disc open/close position. A selection of body materials and elastomers allow for a wide range of applications.
Materials: PVC, PP, PPG, PVDF
Sizes: 3" - 10"
Seals: EPDM, FPM (Viton®)
Features:
NSF 61 Approved Materials
Can be Mounted Vertically or Horizontally
Large Flow Capacity
Optional Drain Plug 
Cr : http://storefront.chemline.com