Swing Wafer Check Valve | Ductile Iron | SS304 Disc | PN16 | NBR
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Ductile Iron Wafer Swing Check Valve, SS304 Disc, NBR Seat, PN16
Cematic's ductile iron wafer swing check valve prevents backflow in water and general service fluid systems. Unlike stainless steel versions, ductile iron offers greater mechanical strength at a lower cost.
This makes it the standard choice in potable water, irrigation, and HVAC applications where SS316's resistance is not required. Its compact wafer design also allows for installation between ANSI B16.1 flanges without additional space, which reduces weight and cost compared to full-body valves.
The swing-type disc is made of SS304 (CF8) stainless steel, offering superior corrosion resistance to iron in the area of greatest contact with the fluid. Additionally, the NBR seat provides reliable sealing in water, air, and non-aggressive petroleum-derived fluids.
Consequently, it is the most economical and reliable backflow prevention component for general industrial and municipal services.
Principle of Operation — Ductile Iron Swing Disc
The disc pivots on a horizontal shaft mounted in the upper part of the body. When fluid flows in the correct direction, pressure pushes the disc upwards, thereby opening the passage.
When the flow stops or reverses direction, the SS304 spring returns the disc to the NBR seat, automatically closing the valve. This protects pumps and upstream equipment without operator intervention.
The wafer format is also installed directly between two ANSI B16.1 flanges using the union studs. Therefore, it does not require its own flanges or special connections, which reduces the cost of the assembly and simplifies installation.
Ductile Iron vs. Stainless Steel — When to Choose Ductile Iron
Ductile iron is the correct choice when the fluid and service do not require the chemical resistance of stainless steel. The following describes cases where ductile iron is the correct choice:
- Potable water and non-corrosive process water: Ductile iron is the standard material in municipal potable water infrastructure. Therefore, it is the lowest cost option when the fluid is clean water without aggressive chlorides or corrosive agents.
- Pumping and water distribution networks: In pumping stations with large diameters, ductile iron also offers superior mechanical strength to stainless steel at a fraction of the cost. It is also the standard specification in municipal hydraulic infrastructure projects.
- HVAC systems and cooling water: In chilled water and return circuits in HVAC systems, ductile iron covers the service more economically. However, for water with aggressive chlorides or treatment agents, SS316 should be specified.
- Compressed air and inert gases: NBR also adequately resists compressed air and non-reactive gases. Therefore, this valve is used in compressor lines and low- and medium-pressure pneumatic systems where stainless steel is not required.
Construction Materials
The body is made of ductile iron, which is the standard material for potable water valves and hydraulic infrastructure. Its mechanical strength and durability are superior to conventional cast iron. The disc is CF8 (SS304) swing type, which is the component in greatest contact with the fluid.
Thus, SS304 ensures corrosion resistance in the sealing area. The spring is SS304, which ensures stable closing force over time without corrosion. The seat is NBR, which is compatible with water, air, and non-aggressive petroleum-derived fluids.
Finally, the wafer format between ANSI B16.1 flanges is the standard connection in industrial and municipal hydraulic infrastructure.
Technical Specifications
| Parameter | Value |
|---|---|
| Valve Type | Wafer swing check valve |
| Installation | Wafer type (between flanges) |
| Flange Standard | ANSI B16.1 |
| Working Pressure | PN16 (232 psi) |
| Body Material | Ductile Iron |
| Disc | CF8 (SS304) swing type |
| Spring | SS304 |
| Seat | NBR |
Fluid Compatibility
This ductile iron wafer swing check valve with NBR seat is compatible with the most common fluids in water systems and industrial infrastructure. The main groups are described below:
- Potable water and process water — ductile iron and NBR are the standard materials in potable water distribution; therefore, it is the most common specification in municipal and industrial hydraulic infrastructure projects
- Raw and treated water in treatment plants — the ductile iron body withstands typical treatment plant conditions; additionally, the SS304 disc offers greater corrosion resistance than iron in the area of greatest exposure
- Compressed air and inert gases — NBR adequately resists air and non-reactive gases; however, for gases with aggressive moisture or contaminants, verify compatibility with Cematic's technical team
- HVAC fluids — chilled water and return water — compatible with standard HVAC system fluids; however, for water with aggressive chemical treatments or high chlorides, specify the stainless steel version
- Light petroleum-derived fluids — NBR is compatible with light oils and petroleum derivatives; however, for aggressive hydrocarbons or those with solvents, verify compatibility with Cematic's technical team
Applications of the Ductile Iron Wafer Swing Check Valve
Potable Water and Municipal Pumping Systems
The ductile iron wafer swing check valve is the standard component in potable water distribution lines and pumping stations. The ductile iron body also offers mechanical resistance and long service life in these services.
Therefore, ductile iron is the preferred specification in hydraulic infrastructure projects where material cost is a determining factor.
Raw Water and Treatment Networks
In pumping stations and filtration plants, this valve also prevents fluid backflow and protects system pumps. The SS304 disc also offers greater corrosion resistance than iron in the area of greatest contact with water.
Consequently, it extends the service life of the critical sealing component compared to valves with an iron disc.
Agricultural Irrigation Systems
In main and secondary irrigation networks, this valve is also compact and easy to install between existing flanges. Its wafer design also reduces the space required and the weight of the assembly compared to a full-body check valve. Therefore, it is the most economical option for protecting irrigation pumps from backflow during emergency shutdowns.
HVAC and Cooling Water Systems
In chilled water and return circuits in air conditioning, this valve also prevents backflow. Therefore, it protects pumps and heat exchangers. NBR is also compatible with standard HVAC fluids without aggressive chemical agents.
Consequently, it is the lowest-cost option for backflow protection in large-scale HVAC systems.
Compressed Air and Gas Lines
In pneumatic systems and compressor lines, this valve also prevents air backflow. Therefore, it protects compressors from emergency shutdowns. NBR also adequately resists air and inert gases.
Therefore, it is a compact and economical solution for compressor protection in low and medium-pressure systems.
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