1. Advantages of eccentric hemispherical valve:
1. Small fluid resistance, its resistance coefficient is equal to that of the pipe section of the same length.
2. Simple structure, small size and light weight.
3. Tight and reliable. At present, the sealing surface material of ball valves is widely used in plastics, which has good sealing performance and has been widely used in vacuum systems.
4. Easy to operate, quick opening and closing, just rotate 90° from full open to full closed, which is convenient for long-distance control.
5. Easy maintenance, the ball valve has a simple structure, the sealing ring is generally movable, and it is convenient to disassemble and ｒｅｐｌａｃｅ.
6. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when passing.
7. Wide range of applications, the diameter ranges from a few millimeters to several meters, and can be used from high vacuum to high pressure.
High platform ball valves can be divided into straight-through, three-way and right-angle types according to their channel positions. The latter two ball valves are used to distribute the medium and change the flow direction of the medium. The following matters should be noted when installing and maintaining a three-piece ball valve:
1. Leave room for the valve handle to rotate.
2. It cannot be used for throttling.
3. Ball valves with transmission mechanisms should be installed upright.
2. The working principle of the eccentric semi-ball valve
is to make the valve unblocked or blocked by rotating the valve chain. The ball valve is light and small in size, can be made into a large diameter, has reliable sealing, simple structure, and convenient maintenance. The sealing surface and the spherical surface are often in a closed state and are not easily eroded by the medium. It is widely used in various industries.
3. The eccentric semi-ball valve is used in the pipeline
to distribute and change the flow direction of the medium. The ball valve is a new type of valve that has been widely used in recent years. It has the following advantages:
1. The fluid resistance is small, and its resistance coefficient is equal to that of the pipe section of the same length.
2. Simple structure, small size, and light weight.
3. Tight and reliable. At present, the sealing surface material of the ball valve is widely used in plastics, which has good sealing performance and has been widely used in vacuum systems.
4. Easy to operate, quick to open and close, only need to rotate 90° from full open to full closed, convenient for long-distance control.
5. Easy to maintain, the ball valve has a simple structure, the sealing ring is generally movable, and it is convenient to disassemble and ｒｅｐｌａｃｅ.
6. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when passing through.
7. Wide range of applications, diameters range from a few millimeters to several meters, and can be used from high vacuum to high pressure. When the ball rotates 90 degrees, the inlet and outlet should all present a spherical surface, thereby cutting off the flow.
The eccentric semi-ball valve is a relatively new type of ball valve. It has some advantages of its own structure, such as no friction when switching, the seal is not easy to wear, and the opening and closing torque is small. This can reduce the specifications of the actuator. Equipped with a multi-turn electric actuator, it can achieve the adjustment and strict shutoff of the medium. It is widely used in working conditions that require strict cut-off, such as petroleum, chemical industry, and urban water supply and drainage.
4. The working principle of the eccentric hemispheric valve is as follows:
A. Opening process
1 In the closed position, the ball is pressed tightly against the valve seat by the mechanical pressure of the valve stem.
2 When the handwheel is turned counterclockwise, the valve stem moves in the opposite direction, and the angular plane at the bottom causes the ball to disengage from the valve seat.
3 The valve stem continues to rise and interacts with the guide pin in the spiral groove of the valve stem, causing the ball to begin to rotate frictionlessly.
4 Until it reaches the fully open position, the valve stem rises to the position and the ball rotates to the fully open position.
B. Closing process
1 When closing, rotate the handwheel clockwise, the valve stem begins to descend and causes the ball to leave the valve seat and begin to rotate.
2 Continue to rotate the handwheel, and the valve stem is acted upon by the guide pin embedded in the spiral groove on it, causing the valve stem and the ball to rotate 90° at the same time.
3 When it is about to close, the ball has rotated 90° without contacting the valve seat.
4 In the last few turns of the handwheel, the angular plane at the bottom of the valve stem mechanically wedges and presses the ball, so that it is tightly pressed on the valve seat to achieve complete sealing.
V. Structural features of eccentric hemispherical valves:
1. Open and close without friction. This function completely solves the problem of traditional [wiki] valves [/wiki] affecting sealing due to mutual friction between sealing surfaces.
2. Top-mounted structure. The valve installed on the pipeline can be directly inspected and repaired online, which can effectively reduce the shutdown of the device and reduce costs.
3. Single valve seat design. Eliminates the problem of abnormal pressure increase in the valve cavity medium affecting the safety of use.
4. Low torque design. The valve stem with special structural design can be easily opened and closed with a small handle valve.
5. Wedge-shaped sealing structure. The valve is sealed by the mechanical force provided by the valve stem, which presses the ball wedge onto the valve seat, so that the sealing performance of the valve is not affected by the change of pipeline pressure difference, and the sealing performance is reliably guaranteed under various working conditions.
6. Self-cleaning structure of the sealing surface. When the ball tilts away from the valve seat, the fluid in the pipeline passes evenly along the sealing surface of the ball at 360°, which not only eliminates the local scouring of the valve seat by the high-speed fluid, but also washes away the accumulation on the sealing surface, achieving the purpose of self-cleaning.
Product use
Eccentric hemispherical valves are suitable for sewage treatment, pulp, alumina, urban heating and heating where strict standards are required; suitable for power plants, hydraulic slag removal or gaseous transmission pipeline control.
