Non-Return Valves - Double Leaf Valve type CD | Mei

MEI CD – Dual Plate Check Valve

The MEI CD is a twin flap (dual plate) check valve designed for installation between flanges. The two plates open under differential flow pressure and close via spring return when flow decreases or reverses. No actuator is required; operation is fully mechanical.

Construction and Connections

• Standard design: wafer, self-centering.
• Available on request: lug and double flanged versions.
• Body types: retainerless or retainer.
• Sizes: DN50–DN500 (CD series).
• Flange compatibility: UNI PN10–PN40, ANSI 150–600.
• Face-to-face: EN 558-1 series 16.
• Pressure testing: API 598.

Materials and Sealing

Body materials: zinc plated carbon steel or AISI 316 stainless steel. Plates: AISI 316L / CF3M. Seat options: metal-to-metal or soft seat (EPDM, Viton/FKM, Buna/NBR), selected based on process fluid, temperature, and leakage class requirements.

Hydraulic Data

For horizontal installation with water at 20°C, Kvs values range from 58 m³/h (DN50) to 10,180 m³/h (DN500). Use manufacturer’s pressure drop chart and adjust for fluid density when sizing for non-water media.

Applications

Suitable for water, cooling circuits, auxiliary industrial networks, air, and compatible gases or liquids. For chemical, seawater, or hot media, verify compatibility of body, plates, springs, and seat materials.

Selection Considerations

Valve selection should not be based solely on pipe DN. Evaluate flow rate, pressure drop, cracking pressure, installation orientation, and minimum velocity for stable plate opening. Low flow rates may cause plate flutter and seat wear.

FAQ

When is the retainerless version selected? Used to minimize potential external leakage paths from shaft penetration points.
Is soft seat available? Yes, EPDM, Viton, or Buna options.
Is an actuator required? No, operation is by flow and spring force only.