The electric stop valve is a new type of valve that has been widely used in recent years. It is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. The closing principle of the electric stop valve is to rely on the electric thrust to rotate the valve stem so that the valve disc sealing surface and the valve seat sealing surface are closely fitted to prevent the flow of the medium. The electric stop valve 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.
Working principle of electric stop valve
The working principle of the electric stop valve is to rely on rotating the valve to make the valve unblocked or blocked. The gate valve is light and small in size. It can be made into a large caliber. It 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.
A. Opening process
1. In the closed position, the valve body 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 without friction.
4. Until it reaches the fully open position, the valve stem rises to the limit 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 gate to rotate 90° at the same time.
3. When it is about to close, the gate body 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, pressing it tightly against the valve seat to achieve complete sealing.
Structural features of electric stop valves
1. Opening and closing without friction. This function completely solves the problem of traditional valves affecting sealing due to friction between sealing surfaces.
2. Top-mounted structure. The valves 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. It eliminates the problem that the medium in the valve cavity affects the safety of use due to abnormal pressure increase.
4. Low torque design. The valve stem with a special structural design can be easily opened and closed with a small handle valve.
5. Wedge sealing structure. The valve relies on the mechanical force provided by the valve stem to press the ball wedge onto the valve seat to seal, so that the sealing 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.
7. The valve body and valve cover of the valve diameter below DN50 are die forgings, and the valve body and valve cover of the valve diameter above DN65 are cast steel parts.
8. The connection forms between the valve body and the valve cover are different, including clamp pin connection, flange gasket connection and self-sealing threaded connection.
9. The valve seat and valve disc sealing surface are made of plasma spray welding or surfacing cobalt-chromium-tungsten carbide, and the sealing surface has high hardness, wear resistance, abrasion resistance and long service life.
10. The valve stem material is nitrided steel. The surface hardness of the valve stem after nitriding is high, wear resistance, abrasion resistance, corrosion resistance and long service life.
Notes on installation of electric stop valve
1. Pay attention to the flow direction of the medium when installing the valve, and install it strictly in the direction indicated by the valve flow arrow.
2. The valve can be installed at any position of the pipeline, and carbon steel or alloy steel valves are selected according to the medium and the temperature of the medium.
3. The electric stop valve should be installed vertically as much as possible, with the valve stem facing up.