Check Valves
Double Door / Rubber Lined Type | DN50 - DN1200
ZNX check valves (also known as non-return valves or backflow preventers) are designed to allow flow in one direction only, automatically closing when flow reverses. They protect pumps, compressors, and other equipment from damage caused by backflow, water hammer, and system pressure surges.
Our two core series are the double door (dual plate wafer) check valve for compact, fast-closing general service, and the rubber lined check valve for seawater, sewage and abrasive media. Both are 100% tested before shipment.
Technical Specifications
| Size Range | DN50 - DN600 (2" - 24") |
| Pressure Rating | PN10, PN16, PN25, ANSI 125/150 |
| Body Material | Cast Iron, Ductile Iron, WCB, SS304, SS316 |
| Disc Material | Ductile Iron (Ni-plated), SS304, SS316, Bronze, NBR-coated |
| Seat Material | NBR, EPDM, Viton, PTFE, Metal-to-Metal |
| Type | Swing Type, Dual Plate Wafer, Ball Check, Lift Check |
| Connection | Wafer, Lug, Flanged (ANSI, DIN, BS, JIS) |
| Working Temp. | -10°C to +120°C (up to +300°C for metal seat) |
| Standard | API 594, API 6D, EN 12334, MSS SP-71 |
| Testing | API 598, EN 12266 |
Key Features
- Low cracking pressure and rapid closure to prevent water hammer
- Compact dual-plate design saves installation space and weight
- Replaceable seats and discs for easy field maintenance
- Resilient seated designs for bubble-tight shutoff
- Stainless steel internal parts for corrosion resistance
- Suitable for horizontal and vertical (upward flow) installation
- Custom spring options available for specific closing characteristics
Applications
- Pump discharge protection in water supply stations
- Boiler feedwater and condensate systems
- Seawater desalination intake and outfall lines
- Wastewater and sewage pumping stations
- HVAC chilled water and condenser water circuits
- Oil, gas, and petrochemical process pipelines
- Fire fighting and sprinkler systems