Author:Site Editor Publish Time: 2018-12-18 Origin:Site
Triple offset butterfly valve and double offset butterfly valve are widely used in the market, and they have their own roles, but if you are not a professional butterfly valve manufacturer, you may have a hard time to know the real difference between them.
Here is the content list:
What is double offset butterfly valve?
What is Triple offset butterfly valve?
What Is Difference of double and triple offset butterfly valve?
The double offset butterfly valve is characterized in that the shaft center of the valve stem is offset from both the center of the disc and the center of the body. The double offset effect allows the disc to be quickly disengaged from the valve seat after the valve is opened, which greatly eliminates unnecessary over-squeezing and scraping of the disc and the valve seat, reduces the opening resistance, reduces wear and improves the seat life.
The scraping is greatly reduced, and the double offset butterfly valve can also be used with a metal valve seat, which improves the application of the butterfly valve in the high temperature field. However, because the sealing principle belongs to the position sealing structure, that is, the sealing surface of the butterfly plate and the valve seat is in line contact, and the elastic deformation caused by the butterfly plate pressing the valve seat produces a sealing effect, the closing position is required (especially metal).
In order to bear high temperatures, a hard seal must be used, but the amount of leakage is large; For zero leakage, soft seals must be used, but not resistant to high temperatures. In order to overcome the contradiction of double eccentric butterfly valve, it is eccentric three times. Its structure characteristic is in the cancellation of double eccentric pole position at the same time, the valve sealing surface of the axis of the cone axis to master cylinder deflection and, after the third eccentric disc sealing part is not another, but a true circle, but an ellipse, the shape of the sealing surface for the asymmetry, so one side tend to be parallel to the centerline of the body.
Tri-eccentric butterfly valve is characterized by a fundamentally changed sealing structure. It is no longer a position seal, but a torsion seal. That is to say, it does not depend on the seat elastic deformation, but completely depends on the seat contact surface pressure to achieve the sealing effect. Solve the metal valve seat zero leakage problem, solve the contact pressure problem. The force is proportional to the medium pressure, resulting in a solution of high pressure and high temperature.
Hard seals must be used to withstand high temperatures, but with large amounts of leakage. To achieve zero leakage, a soft seal must be used, but it cannot withstand high temperatures. In order to overcome the contradiction of the double eccentric butterfly valve, the butterfly valve was subjected to a third eccentricity. At the same time, the structural characteristics of the double eccentric shaft deflect the butterfly valve plate sealing end face cone shaft. That is to say, after the third eccentricity, the butterfly sealing member is no longer a solid circle or an ellipse, the sealing surface is asymmetrical in shape, the center line body is inclined, and the other side is parallel to the center line body.
The third feature fundamentally changes the position of the sealing structure and the seal, and is no longer a problem of torque sealing. That is to say, the seat does not depend on the elastic deformation, but relies entirely on the contact pressure of the seat to achieve the sealing effect. A zero-leakage metal seat that solves the problem because the contact pressure is proportional to the pressure port and resists high pressures and temperatures.
The above is the difference between double and triple offset butterfly valve, I hope it can help you. The flow of medium can be controlled by changing the deflection Angle of the butterfly plate. If you want further information, please visit our website. You are always welcome.