The double-disc check valve consists of two symmetrical discs and is typically installed in horizontal or vertical pipelines with upward flow. Its structure is relatively simple. The discs can close under medium pressure to prevent backflow and open under medium pressure to allow forward flow. Therefore, they are commonly used as check valves for pipelines with high-volume fluid flow.
Structural Features
The core components of a double-disc check valve are two butterfly-shaped or semi-circular discs, which are hinged to the valve body. The discs can rotate freely around the hinges. When fluid flows in the forward direction, the fluid pressure pushes the discs open, allowing smooth passage. If backflow occurs, the reverse pressure forces the discs to close tightly, preventing fluid reversal. The valve body typically adopts a compact design with a short structure, making it lightweight and easy to install and maintain.
Specification
Design Standard: API 594
Size Range: 2"-76" (DN50-DN1900)
Pressure Rating: ASME CLASS 150-2500 (PN16-PN420)
Body Material: Carbon Steel, Stainless Steel, Alloy Steel, Duplex Stainless Steel
End Connection: RF, LUG, RTJ, WAFER, WJ
Operation: None
Fire Safe Design: Yes
Working Principle
When the forward fluid pressure exceeds the opening pressure of the discs, they are pushed open, permitting fluid flow. When fluid stops or reverses, the discs close rapidly under their own weight and backflow pressure, forming a seal to block backflow. This rapid closure effectively mitigates water hammer effects, protecting the pipeline system.
Applications
Due to their compact size, lightweight, and ease of installation, double-disc check valves are widely used in fluid piping systems, especially in space-constrained environments. Common applications include:
Water Treatment Systems: Preventing backflow when pumps stop, safeguarding pumps and other equipment.
Petrochemical Industry: Used in pipelines carrying various media to prevent backflow and ensure production safety.
HVAC Systems: Preventing reverse flow of hot/cold water to maintain system operation.
Food & Beverage Industry: Used in high-hygiene piping systems to prevent medium contamination.
Power Industry: Applied in boiler feedwater and condensate systems to ensure stable operation.
Urban Water Supply Networks: Primarily preventing backflow at network endpoints to ensure water safety.
