The double offset butterfly valve is a type of butterfly valve that optimizes sealing performance through two geometric offset designs. Its core features and advantages are as follows:
1. Structural design principle
Double eccentric geometric features
First eccentricity: the valve stem axis deviates from the geometric center of the butterfly plate (eccentricity A);
Second eccentricity: the valve stem axis deviates from the center of the valve body channel at the same time (eccentricity B).
The double offset forms a staggered layout of the butterfly plate rotation center and the sealing surface.
Motion characteristics
When opening, the butterfly plate instantly detaches from the valve seat, and when closing, it gradually presses the sealing surface, reducing friction by more than 80% throughout the process;
Avoid continuous scratching and wear of concentric butterfly valves, and extend the life of seals by 3-5 times.
2. Core performance advantages
Improved sealing reliability
Adopting line contact sealing structure: the butterfly plate squeezes the valve seat to produce elastic deformation to achieve sealing;
Supporting metal hard seals (such as stainless steel + graphite composite), temperature resistance up to 200℃
Enhanced adaptability to working conditions
Pressure resistance: up to PN64 (Class 400);
Media compatibility: suitable for sewage, slurry and corrosive fluids containing suspended particles;
Opening and closing torque: 40% lower than concentric butterfly valve, easier to operate.
3. Typical application scenarios
Water conservancy and municipal administration
Flow control of large water plants (pipes above DN300);
Solid medium cutoff in sewage treatment plants.
Industrial system
Chemical medium and low pressure steam pipelines (≤200℃);
Cooling water system regulation in the energy field.
4. Technical limitations and improvements
Limitations
The seal depends on the accuracy of the closing position, and micro-leakage may occur under high pressure conditions;
The pressure bearing capacity of metal seals is weaker than that of three-eccentric butterfly valves.
Iteration direction
Improved to an elastic multi-layer seat structure to compensate for thermal deformation (temperature difference ±150℃);
Surface hardening treatment (such as tungsten carbide spraying) improves wear resistance
