Double Flap Check Valve

Double-flap check valve is a type of swing check valve. It adopts a double-flap symmetrical structure and can be opened and closed quickly by rotating around the rotating shaft. It is suitable for low flow rate scenarios of large and medium-diameter pipelines (DN≥150). It can effectively disperse the closing impact force and reduce the water hammer effect.

‌Core features‌:

‌Lightweight design‌: The wafer-type structure shortens the length to 1/4~1/8 of the traditional flange check valve, and reduces the weight to 1/4~1/20, reducing the installation cost; ‌Fast response‌: Spring-assisted or gravity reset design, closing time ≤0.5 seconds, blocking the medium backflow efficiency by more than 30%; ‌Wide adaptability‌: Supports horizontal, vertical and any angle installation, suitable for water, oil, steam and other media.

Core structure and working principle

‌Key components‌

‌Double disc‌: metal disc or composite material (such as stainless steel + rubber coating), symmetrically distributed on both sides of the shaft to reduce the risk of deformation due to unilateral force;
‌Shaft mechanism‌: high-strength alloy steel pin with self-lubricating bearing to ensure low-friction rotation (torque ≤10N·m);
‌Sealing system‌: metal hard seal (high pressure and high temperature) or elastic soft seal (including granular medium), leakage level can reach ANSI/FCI 70-2 Class VI.
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Working principle‌

‌Forward flow‌: medium pressure pushes the disc to rotate and open, the maximum opening angle can reach 75°~90°, and the flow resistance coefficient is as low as 0.2~0.3;
‌Reverse closing‌: when the medium flows back, the disc is quickly closed by gravity/spring force and reverse pressure, and the sealing surface fitting pressure can reach 1.5 times the pipeline pressure.

 

Double flap check valve

 

Selection and installation specifications
‌Key points for selection‌
‌Media matching‌: Clean liquids are preferred to metal seals; medium containing particles requires rubber lining or pre-filter;
‌Pressure adaptation‌: Forged steel valve bodies are required for high-pressure pipelines (≥Class 600), and cast iron or cast steel can be selected for low-pressure scenarios;
‌Slow closing requirements‌: It is recommended to install hydraulic dampers for long-distance water pipelines to extend the closing time to 3~5 seconds to eliminate water hammer.
‌Installation requirements‌
‌Directional control‌: When installed vertically, the medium needs to flow from bottom to top, and no additional support is required for horizontal installation;
‌Maintenance cycle‌: For valves DN≥600, check the shaft wear every 2 years and lubricate the bearings regularly (grease temperature resistance ≥150℃)

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