A swing check valve allows fluid to flow in only one direction, preventing backflow. Here’s how it accomplishes this:
Core Components
The swing check valve's operation relies on its simple yet effective design:
- Valve Body: The outer structure of the valve.
- Seat: The surface against which the disc seals to prevent reverse flow.
- Disc: The moving part that opens and closes to allow or stop flow. This disc is linked to a hinge.
- Hinge: Enables the disc to swing open and closed.
Operational Mechanism
Here’s the step-by-step process of how a swing check valve works:
- Forward Flow: When fluid flows in the intended direction, the force of the flow pushes against the disc.
- Disc Rotation: As the flow increases, the disc rotates around its hinge, moving away from the seat. According to the reference, "Upon encountering a specified flow rate, the disc rotates to a horizontal position, enabling forward flow."
- Open Position: The disc swings open to allow the fluid to pass through the valve.
- Flow Reduction/Cessation: When the flow slows or stops, the force pushing the disc open decreases. Gravity, along with any back pressure, will start moving the disc towards the seat.
- Backflow Prevention: When the flow stops, or tries to reverse direction, the disc automatically swings back against the seat. "It returns to the valve seat when the flow stops to prevent backflow", as indicated in the reference. This creates a seal, preventing backflow.
Practical Insights
- Simplicity: The swing check valve’s simple design makes it reliable and easy to maintain.
- Low-Pressure Systems: These valves are effective in low-pressure systems because they do not require a strong reverse flow to close.
- Applications: Common applications include water supply lines, wastewater treatment plants, and various industrial piping systems.
Advantages
- Automatic Operation: The valve operates automatically based on flow conditions.
- Minimal Parts: Few parts make it less prone to failure.
- Cost-Effective: Generally less expensive than other types of check valves.
In summary, a swing check valve uses a hinged disc that swings open to allow forward flow and swings shut against the valve seat to prevent backflow, all in response to changes in flow rate.
