https://www.wvf-valve.com/gate-valve/resilient-soft-seated-gate-valve/f4-gate-valve.html
The F4 gate valve shall have a smooth and oversize waterway and have the marking D.I. or Ductile Iron on the body.
Full bore gate valve
NBR/EPDM fully vulcanized wedge
Application of low friction sliding element
Wedge nut made of forged brass-replaceable
Stainless steel spindle bearing acting both horizontal and vertical way
O-ring spindle sealing packing cork protected against contact with medium
Packing cork protected against dirt penetration
Body bonnet Zinc coated screws protected by wax
Both inner and out part is Fusion-bonded epoxy 200-250 microns.