Unlike swing check valves that rely on gravity and backflow to close, the dual plate design uses torsion springs to assist in closing. The plates close nearly the instant the flow velocity decreases, preventing the slam and subsequent pressure surges (water hammer) that can damage sensitive equipment. Material Selection and Durability To ensure longevity in corrosive or high-pressure environments, material selection is critical. Common configurations include: Body: Cast Iron, Carbon Steel (WCB), Stainless Steel (CF8M), Duplex Steel, or Aluminum Bronze. Plates: SS316, Monel, or Hastelloy for aggressive media. Seats: Metal-to-metal for high temperatures or resilient seats (EPDM, Viton, Buna-N) for bubble-tight shutoff. Technical Note: For high-temperature steam applications, $Stellite$ hard-facing on the seat is recommended to prevent erosion and wire-drawing. Dual plate check valves are the preferred choice for: Oil & Gas: Refineries and offshore platforms where space is at a premium. Water Treatment: Desalination plants and municipal pumping stations. HVAC: Chilled water systems and boiler feed lines. Chemical Processing: Handling aggressive fluids with specialized alloy plates.