Simply put, an electric valve uses an electric actuator to control the valve, thereby achieving the opening and closing of the
valve. It can be divided into two parts: the upper part is an electric actuator, and the lower part is a valve. The action force distance is larger than that of an electric valve, and the opening and closing speed of the electric
gate valve can be adjusted. The structure is simple and easy to maintain. During the action process, it is not easy to be damaged due to jamming. However, there must be a gas source, and its control of the electric valve is simply to use an electric actuator to control the valve, thereby achieving the opening and closing of the valve. It can be divided into two parts: the upper part is an electric actuator, and the lower part is a valve. The action force distance is larger than that of electric valves, and the opening and closing speed of electric gate valves can be adjusted. The structure is simple and easy to maintain. During the action process, due to the buffering characteristics of the gas itself, it is not easy to be damaged due to jamming. However, there must be a gas source, and its control system is also more complex than that of electric valves.
The electric globe valve and the flange gate valve belong to one type of valve, consisting of an electric or pneumatic actuator and a globe valve. The difference is that its closing part is a valve body, which rotates around the centerline of the valve body to achieve opening and closing. Gate valves are mainly used in pipelines to cut off, distribute, and change the flow direction of the medium. Two-piece ball valves and three-piece ball valves are one new type of valves widely used in recent years.
The Differences between Electric Gate Valves and Electric Globe Valves
1. Different sealing surfaces
When the gate valve is opened and closed, the sealing surface of the valve core and valve seat always contacts and rubs against each other. The valve makes the sealing surface easy to wear, especially when the valve is in a close state, the pressure difference between the front and rear of the valve core is large. The sealing surface wear is even more severe. Once the valve disc of a globe valve is in an open state, there is no longer contact between its seat and the sealing surface of the valve disc, resulting in less mechanical wear on its sealing surface. However, if the medium contains solid particles, it is easy to damage the sealing surface. The sealing surface of the gate valve has a certain degree of self-sealing ability. Its valve core tightly contacts the sealing surface of the valve seat with the medium pressure, achieving tightness and no leakage.
The sealing surfaces of the globe valve only come into contact with each other when fully closed, and the relative slip between the forcibly closed valve core and the sealing surface is very small, resulting in minimal wear on the sealing surface. The wear of the sealing surface of the globe valve is mostly caused by debris in front of the valve core and sealing surface, or by the lack of tightness in the closed state, which causes high-speed flushing of the medium.
2. Different structures
Gate valves have a more complex structure and larger height dimensions than globe valves. From the perspective of appearance, gate valves are shorter and taller than globe valves, especially rising stem gate valves that require higher height space. This should be noted in selection when installation space is limited.
3. Different flow resistance
When the gate valve is fully open, the entire flow path is straight, and the pressure loss of the medium during operation is minimal. Compared with the globe valve, its main advantage is that the fluid flow resistance is small. The flow resistance coefficient of ordinary gate valves is about 0.08 to 0.12, while the resistance coefficient of ordinary globe valves is about 3.5 to 4.5. The opening and closing force is low. Gate valves are usually suitable for operating conditions that do not require frequent opening and closing, and maintain the gate fully open or fully closed. They are not suitable for regulating or throttling use.
4. Different itineraries
The stroke of the gate valve is larger than that of the globe valve.
5. Different flow directions
When installing a globe valve, the medium can enter from below the valve core and from above. The advantage of medium entering from below the valve core is that the packing is not under pressure when the valve is closed, which can extend the service life of the packing and replace the packing when the pipeline in front of the valve is under pressure. The disadvantage of medium entering from below the valve core is that the driving torque of the valve is relatively high, which is about 1.05 to 1.08 times that of entering from above. The axial force on the valve stem is large, and the valve stem is prone to bending. Therefore, the medium entry method from below is generally only applicable to small diameter globe valves (below DN50), while globe valves above DN200 use the medium entry method from above valves.
Electric globe valves generally use the method of medium entering from above valves. The disadvantage of media entering from above is exactly the opposite of entering from below. The flow direction of the gate valve is the same when entering from both directions.
Compared with gate valves, globe valves have the advantages of simple structure, good sealing performance, and convenient manufacturing and maintenance. The disadvantage is that the liquid resistance is high, and the opening and closing forces are large.
6. Different maintenance processes
The maintenance of gate valves is not suitable for on-site pipelines, and the valve seats and discs of most globe valves can be replaced online without the need to remove the entire valve from the pipeline. This is very suitable for situations where the valve and pipeline are welded together. Of course, there are more than just these differences between gate valves and globe valves. We need to distinguish their similarities and differences well in selection and use to avoid errors.
The application range of globe valves and gate valves is determined based on their characteristics. In smaller channels, when good globe sealing is required, globe valves are often used. In steam pipelines and large-diameter water supply pipelines, gate valves are used due to the general requirement of low fluid resistance.
