Globe valves and gate valves are two widely used valves. The following is a detailed introduction to the differences between globe valves and gate valves.
1. The working principles are different. The globe valve is a rising stem type, and the handwheel rotates and rises with the valve stem. The gate valve is a handwheel rotation, and the valve stem rises. The flow rate is different. The gate valve requires full opening, but the globe valve does not. The gate valve has no inlet and outlet direction requirements, and the globe valve has specified inlets and outlets! The imported gate valve and the globe valve are shut-off valves and are the two most common valves.
2. From the appearance point of view, the gate valve is shorter and taller than the globe valve, especially the rising stem valve requires a higher height space. The sealing surface of the gate valve has a certain self-sealing ability, and its valve core is tightly in contact with the valve seat sealing surface by the medium pressure to achieve tightness and no leakage. The valve core slope of the wedge gate valve is generally 3~6 degrees. When the forced closure is excessive or the temperature changes greatly, the valve core is easy to get stuck. Therefore, high-temperature and high-pressure wedge gate valves have taken certain measures to prevent the valve core from getting stuck in the structure. When the gate valve is opened and closed, the valve core and the valve seat sealing surface are always in contact and rub against each other, so the sealing surface is easy to wear, especially when the valve is in a state close to closing, the pressure difference between the front and rear of the valve core is large, and the wear of the sealing surface is more serious.
3. Compared with the imported globe valve, the main advantage of the gate valve 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 resistance coefficient of the ordinary globe valve is about 3.5~4.5. The opening and closing force is small, and the medium can flow in two directions. The disadvantages are complex structure, large height size, and easy wear of the sealing surface. The sealing surface of the globe valve must be closed by a forced force to achieve sealing. Under the same caliber, working pressure and the same drive 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 imported electric valve.
Fourth, the sealing surfaces of the globe valve only contact each other when it is completely closed. The relative slip between the forced closed valve core and the sealing surface is very small, so the wear of the sealing surface is also very small. The wear of the globe valve sealing surface is mostly caused by the presence of debris between the valve core and the sealing surface, or by the high-speed scouring of the medium due to the loose closing state. When installing the globe valve, the medium can enter from the bottom of the valve core and from the top. The advantage of the medium entering from the bottom of 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 the medium entering from the bottom of the valve core is that the driving torque of the valve is large, about 1.05~1.08 times that of the upper entry, the axial force on the valve stem is large, and the valve stem is easy to bend. For this reason, the medium entering from the bottom is generally only suitable for small-diameter manual globe valves, and the force of the medium acting on the valve core when the valve is closed is limited to no more than 350Kg. Imported electric globe valves generally use the method of medium entering from the top. The disadvantage of the medium entering from the top is just the opposite of the method of entering from the bottom.
5. Compared with gate valves, the advantages of globe valves are simple structure, good sealing performance, and easy manufacturing and maintenance; the disadvantages are large liquid resistance and large opening and closing forces. Gate valves and globe valves are fully open and fully closed valves. They are used to cut off or connect the medium and are not suitable for use as import regulating valves. The application range of globe valves and gate valves is determined by their characteristics. In smaller channels, when better shut-off sealing is required, globe valves are often used; in steam pipelines and large-diameter water supply pipelines, gate valves are used because the fluid resistance is generally required to be small.
Post time: Nov-19-2024