The electric valve simply uses the electric actuator to control the valve, so as to realize the opening and closing of the valve. It can be divided into upper and lower parts, the upper part is the electric actuator, and the lower part is the valve. The action force distance is larger than that of the electric valve, the switching speed of the electric gate valve can be adjusted, the structure is simple, and it is easy to maintain. During the action process, due to the buffer characteristics of the gas itself, it is not easy to be damaged due to jamming, but there must be a gas source, and its control system is also More complicated than electric valves. Electric globe valve and flange gate valve are the same type of valve, which consists of electric actuator or pneumatic actuator and globe valve. The difference is that its closing part is a valve body, and the valve body rotates around the center line of the valve body to achieve A valve that opens and closes. The gate valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline.
The difference between electric gate valve and electric globe valve
1. Different sealing surfaces
When the gate valve is opened and closed, the valve core and the valve seat sealing surface are always in contact and friction with each other, so the sealing surface is easy to wear, especially when the valve is close to the closed state, the pressure difference between the front and rear of the valve core is large, and the sealing surface wear is even more serious ; Once the disc of the globe valve is in the open state, there is no longer contact between its valve seat and the sealing surface of the disc, so the mechanical wear of its sealing surface is small, but if the medium contains solid particles, it is easy to damage the sealing surface. . The sealing surface of the gate valve has a certain self-sealing ability, and its valve core is tightly contacted with the sealing surface of the valve seat by the medium pressure, so as to be tight and leak-proof. The inclination of the spool of the wedge gate valve is generally 3~6 degrees. When the spool is forced to close excessively or the temperature changes greatly, the spool is easy to get stuck. Therefore, high temperature and high pressure wedge gate valves have taken certain measures to prevent the valve core from being stuck in structure. The sealing surface of the globe valve must be closed by a forced force to achieve sealing. Under the same diameter, working pressure and the same driving device, the driving torque of the globe valve is 2.5~3.5 times that of the gate valve. This point should be paid attention to when adjusting the torque control mechanism of the electric valve. The sealing surfaces of the globe valve contact each other only when they are completely closed. The relative slip between the valve core and the sealing surface that is forced to close is very small, so the wear of the sealing surface is also very small. The wear of the sealing surface of the globe valve is mostly due to the debris before the valve core and the sealing surface, or due to the loose closing state, which causes the high-speed scouring of the medium.
2. Different structure
Gate valves are more complex in structure and larger in height than globe valves. From the perspective of appearance, gate valves are shorter and taller than globe valves. In particular, rising stem gate valves require a higher height space, which should be paid attention to in the selection of models when the installation space is limited.
3. Different flow resistance
When the gate valve is fully open, the entire flow channel is straight, and the pressure loss of the medium is the smallest at this time. Compared with the globe valve, its main advantage is that the fluid flow resistance is small. The flow resistance coefficient of the ordinary gate valve is about 0.08~0.12, while the ordinary gate valve The resistance coefficient of the globe valve is about 3.5~4.5. Small opening and closing force. The gate valve is usually suitable for the conditions that do not need to be opened and closed frequently, and the gate is kept fully open or fully closed, and is not suitable for adjustment and throttling. The flow resistance of the globe valve in the entire stroke is large, the unbalanced force is large, and the required driving force or torque is correspondingly much larger. But it is very suitable for fluid regulation and throttling. For high-speed flowing medium, the gate can cause vibration of the valve when the gate is partially opened, and the vibration may damage the sealing surface of the gate and the valve seat, and throttling will cause the gate to be eroded by the medium.
4. Different itineraries
The stroke of the gate valve is larger than that of the globe valve.
5. The flow direction is different
When the globe valve is installed, the medium can enter from the bottom of the spool and enter from the top in two ways. The advantage of the medium entering from below the valve core is that the packing is not under pressure when the valve is closed, which can prolong the service life of the packing, and can replace the packing when the pipeline in front of the valve is under pressure. The disadvantage of the medium entering from the bottom of the valve core is that the driving torque of the valve is large, which is about 1.05~1.08 times that of entering from the top, the axial force on the valve stem is large, and the valve stem is easy to bend. For this reason, the method of entering the medium from the bottom is generally only suitable for small-diameter globe valves (below DN50), and the globe valves above DN200 use the method that the medium flows in from the top. The electric globe valve generally adopts the way that the medium enters from above. The disadvantage of media entry from above is just the opposite of that from below. The flow direction of the gate valve is the same from both sides. Compared with gate valve, the advantages of globe valve are simple structure, good sealing performance, convenient manufacturing and maintenance; the disadvantage is that the liquid resistance is large, and the opening and closing force is large.
6. Different maintenance procedures
The maintenance of the gate valve is not suitable for on-site pipelines, and the valve seat and disc of most globe valves can be replaced online without removing the entire valve from the pipeline. is very suitable. Of course, the difference between gate valve and globe valve is more than these. We must distinguish their similarities and differences well in selection and use in order to avoid mistakes. The application range of globe valves and gate valves is determined according to their characteristics. In smaller passages, when better shut-off and sealing performance is required, globe valves are often used; in steam pipelines and large-diameter water supply pipelines, gate valves are generally used because fluid resistance is generally required to be small.