Eccentric rotary control valve principle of operation

The eccentric rotary control valve is a kind of straight-through valve structure with a novel structure and low fluid resistance. The rotation center of the spool is not concentric with the rotation axis, which can reduce the wear of the valve seat and prolong the service life. The back of the spool is equipped with a guide wing, which is conducive to stable fluid flow. It has excellent stability. Also, it has the advantages of large flow rate and wide adjustable range. It is especially suitable for the control of process systems containing slurry.

Eccentric rotary control valve structure

The eccentric rotary control valve body flow path is simple, low resistance. Compared with single and double-seat valves of the same diameter, it has a larger flow capacity. But the weight is only about 1/3 of it. The eccentric rotary control valve adopts rotary motion, which improves the sealing of the stuffing box. Also has a larger output force, so the valve leakage is smaller. Rigidity is larger, and it can work reliably under rated differential pressure. The eccentric rotary spool and stem only rotate, so the friction force is very small when it opens and closes. When the spool and the valve seat are in contact with each other, the flexible arm of the spool produces small elastic deformation and elastic tightening force under the thrust of the actuator, which makes the contact between the spool and the valve seat tighter and stronger. Therefore, the leakage of the eccentric rotary control valve is very small. At the same time, the thrust required to close the valve is smaller compared with ball valves and butterfly valves.

Eccentric rotary control valve features

1. Reliable performance

The special seat seal design can automatically center, self-lap, and dynamically align with the spool, which can improve service life. Sealed metal bearings prevent the spool from rotating by preventing particle accumulation on the shaft surface.

2. Long seat life

Durable, robust metal or ceramic seat seals and eccentric spools reduce spool-seat friction during opening and closing, improving damage to the seat sealing surface and resistance during the opening. When the spool is rotated to the closed position, the spool and the seat seal will have an automatic overlapping effect, so that a more reasonable fit is obtained between the sealing surfaces. The material of the seat seal can be 316 stainless steel, A105 forged carbon steel welded carbide, and ceramic.

3. Easy installation

The valve body with flange can be connected with different grades of pipe flanges. With different design requirements, it can also avoid having exposed flange screws. The positioning surface and overall effect during installation are also better. A pressed flangeless valve body is also available, which can be positioned by flange screws during installation.

4. Multiple operations are possible

The self-centering seat seal and robust spool can achieve sealing when used in either direction of forward or reverse flow. With a backward flow direction, the outlet turbulence zone is away from the seat sealing surface. In addition, the 90°C travel of the spool helps reduce the scouring of the spool against the flowing medium, reducing the possibility of damage.

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