The triple eccentric butterfly valve is a rotary valve. The three eccentrics are all placed on the valve plate. In the valve manufacturing process, the outer edge of the valve plate adopts a partial outer spherical structure. The outer eccentric spherical surface is polished to a roughness of Ra0.4, and the spherical surface is chrome-plated or surfacing. The hardness reaches HRC45~60.
The pressure resistance of the triple eccentric butterfly valve is up to 26MPa, the temperature resistance is as low as -196℃, and the temperature is as high as 700℃, and the seal reaches zero leakage. It can be seen that it is precisely because of the innovative structural characteristics of the triple eccentric butterfly valve that it has the following main characteristics.
The new triple eccentric butterfly valve is designed with double safety structure. In order to prevent the deformation of the disc, the dislocation of the valve stem, and the occlusion of the sealing surface caused by the influence of fluid pressure and temperature, two independent thrust rings are installed on the upper and lower sides of the disc to ensure that the valve is in any working condition. In order to prevent the valve stem from being damaged and flying out and causing unexpected accidents, independent valve stem flying-out prevention mechanisms are designed at the inner and outer parts of the lower end of the valve.
The shape of the valve plate of the triple eccentric butterfly valve is an elliptical cone, and its surface is surfacing with hard alloy, which has excellent wear resistance. The floating U-shaped stainless steel valve seat has the function of automatically adjusting the center.
When the valve is opened, the elliptical cone sealing surface valve plate first disengages the U-shaped elastic valve seat. Then rotate again; when the valve plate is closed, the valve plate rotates, and the valve plate automatically adjusts the center to the elastic valve seat under the action of the eccentric shaft, and presses the valve seat to deform the valve seat until the valve seat and the valve plate elliptical conical sealing surface are closely matched.
It is achieved that the disc does not scratch the valve seat when the valve is switched on and off, and the torque of the valve stem is directly transmitted to the sealing surface through the disc, and the opening torque is small, thus eliminating the common jumping phenomenon when opening the valve, that is, eradicating the dead zone (no sense band) . This design without dead zone enables the triple eccentric butterfly valve to enter the controllable area almost from 0 opening to 90 opening, and its control ratio can be as high as 100:1 or more, which is twice that of ordinary butterfly valves.
The biggest feature of the triple offset butterfly valve is that the sealing structure is fundamentally changed. It is no longer a position 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 sealing effect.
This kind of sealing structure enables the triple eccentric butterfly valve to achieve hard sealing level VI and achieve true zero leakage. At the same time, due to the selection of metal valve seats and the structural characteristics of the face seal, the problem of high temperature and high pressure resistance is also easily solved.
In addition, the water flow balancing valve adopts the body seat structure. It makes the valve structure more compact, reduces the chance of the valve seat directly contacting the medium, reduces the degree of erosion of the valve seat, and also effectively prevents the influence of small solids in the medium and the possible sealing surface occlusion caused by thermal expansion. Thus prolonging the service life of the valve seat.
The new triple eccentric butterfly valve can not only replace the body seat, but also the sealing surface of the disc and the disc are independent, and the sealing surface of the disc can also be replaced, which greatly reduces the maintenance cost.