Author:Site Editor Publish Time: 2019-01-02 Origin:Site
The valve stem axis simultaneously deviates from the disc center and the body center, and the valve seat turns the axis and the valve body channel axis has certain Angle, is called the Triple offset butterfly valve
l What is Triple offset butterfly ？
l What is the feature of Triple offset butterfly ?
The axial center of the valve stem is simultaneously deviated from the center of the disc and the center of the body, and the rotation axis of the valve seat has a certain angle with the axis of the valve body passage, which is called a triple offset butterfly valve.
To withstand high temperatures, a hard seal must be used, but the amount of leakage is large; for zero leakage, a soft seal must be used, but it is not resistant to high temperatures. In order to overcome the contradiction of the double offset butterfly valve, the butterfly valve was subjected to the third eccentricity. The structural feature is that the conical axis of the sealing surface of the disc is deflected to the axis of the main cylinder at the same time as the offset position of the double offset stem, that is, after the third eccentricity, the sealing section of the disc is not In addition, it is a true circle, but an ellipse, and its sealing surface shape is also asymmetrical, with one side inclined to the center line of the body and the other side parallel to the center line of the body.
Tri-eccentric butterfly valve is widely used in metallurgical, electric power, petrochemical, water supply and drainage, municipal construction and other industrial pipelines with medium temperature ≤425℃. Material is divided into: cast iron, cast steel, stainless steel, its main features are:
The biggest feature of this third eccentricity is that it fundamentally changes the sealing structure, no longer a positional seal, but a torsion seal, that is, it does not rely on the elastic deformation of the valve seat, but completely relies on the contact surface pressure of the valve seat to achieve the seal. The effect solves the problem of zero leakage of the metal valve seat in one fell swoop, and the contact surface pressure is proportional to the medium pressure, and the high pressure and high temperature are also solved.
Since its inception, the three-offset disc valve has undergone a process of self-improvement and continuous development in order to meet the increasingly severe working conditions. Even the most basic zero leakage, theoretically three offset disc valves can be achieved, but in fact depends on careful design and precision manufacturing.
In summary, the three offset butterfly valves, as the crystallization of the latest technology of valves, the length of various valves, and the shortness of avoiding various valves, will surely receive more and more attention from users and designers.
In many Asia Pacific countries, due to the limitations of their own valve design and manufacturing level, as well as the influence of traditional textbooks, the bias against the disc valve is still large. And at the same time, the advanced developed industrial countries of Europe and America are vigorously promoting, actively using disc valve. The truth is very simple, disc valve has changed.
Triple eccentric disc valve can withstand pressure up to 2500 pounds, temperature down to -196 ℃, up to 700 ℃, seal up to 0 leakage, regulation ratio up to 100:1. That is to say, in a variety of harsh, critical process control pipeline, whether the switch valve or control valve, as long as the selection of appropriate, can be safely used today, and the cost is low.
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