APCO Double Door Check Valves (CDD)
APCO Double Door Check Valves by DeZURIK are designed to automatically prevent back-flow in systems where it is desirable to permit flow in one direction and prevent flow in the opposite direction. Double door check valves are recommended for clean liquids and gasses and have an excellent performance reputation in refineries, petrochemical, gas liquefaction, other process industries and HVAC applications because of their cost-efficient design and non-slam properties.
Double door check valves are spring loaded for fast, non-slam shut-off against the elastomer or metal body seat. When the pump starts and the downstream flow creates the required pressure drop in the forward direction, the double doors will automatically open. When the pump stops and the flow ceases, the torsion of the spring will automatically close the double doors prior to flow reversal. This creates a positive shut-off against flow reversal and minimizes system surges and water hammer.
APCO CDD Double Door Check Valves are available in sizes 2-36" (50-900mm). Body materials include Ductile Iron, Carbon Steel and 316 Stainless Steel. Wafer body valve sizes 2-6" (50-150mm) are dual rated to ASME B16.5 Class 150/300. Valve sizes 8" (200mm) and larger are rated to ASME Class 150.
Quick Close to Reduce Water Hammer
Shut-off is achieved via the fully automatic, spring-assisted discs that close near zero flow velocity. The lightweight, split disc design creates a positive shutoff prior to flow reversal and helps minimize valve slam and surge.
Ductile Iron, Carbon Steel or 316 Stainless Steel Construction
The ductile iron body maintains the anti-corrosive properties of cast iron while achieving yield strength comparable to carbon steel. Ductile iron also offers higher pressure/temperature ratings than cast iron. The CDD Double Door Check Valve is also available in Carbon Steel and Stainless Steel for corrosion resistance or higher pressure services.
Resilient or Metal Seats
Resilient seats in Terpolymer of Ethylene Propylene & A Diene (EPDM), Acrylonitrile-Butadiene (NBR) or Fluoro Rubber (FKM) ensure a bubble tight seal that meets or exceeds API 598 test requirements. Lapped metal seats meet or exceed API 598 test requirements.
Cost Efficient Design
The low weight and short laying length of the CDD Double Door Check Valve saves initial cost, requires less space, and is easier to install when compared to full-body, swing-type check valves. Although this valve is light in weight, it is capable of heavy duty, continuous operation. APCO carbon steel and stainless steel CDD Double Door Check Valves meet ASME B16.10/API 594 face-to-face dimensions and ASME B16.5 Flange Dimensions.
Minimal Head Loss
The contoured body of the CDD Double Door Check Valve provides a short and straight flow path that generates very little turbulence. Additionally, the spring-loaded discs are designed with very low cracking pressure which reduces the amount of energy required to open the valve.
Double Door Check Valves (CDD) Specifications
Ductile iron, carbon steel, stainless steel, other materials available on application
ASME Class 150 for lugged valves; ASME Class 150/300 dual rated for 2-6” (50-150mm) wafer valves; ASME Class 150 for 8” (200mm) and larger wafer valves
2-36” (50-900mm); larger sizes available on application