Globe valve and gate valve are two kinds of valves that are widely used. The detailed difference between globe valve and gate valve is introduced below.
1. The working principle is different. The globe valve is a rising valve stem type, and the handwheel rotates and rises together with the valve stem. The gate valve is rotated by the handwheel, and the valve stem moves upward. The flow is different, the gate valve requires full opening, and the globe valve does not. The gate valve has no import and export direction requirements, and the globe valve has specified import and export! Inlet gate valve and globe valve are shut-off valves and are the two most common valves.
2. From the perspective of appearance, the gate valve is shorter and taller than the globe valve, especially the rising stem valve needs a higher height space. 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 slope of the spool of the wedge gate valve is generally 3 to 6 degrees. Therefore, high temperature and high pressure wedge gate valves have taken certain measures to prevent the valve core from being stuck in structure. 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 more serious. .
3. Compared with the inlet 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, and 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 disadvantage is that the structure is complex, the height size is large, and the sealing surface is easy to wear. 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 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 imported electric valve.
4. The sealing surfaces of the globe valve contact each other only when they are completely closed. The relative slippage between the forcibly 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 sealing surface of the globe valve is mostly due to the presence of debris before the valve core and the sealing surface, or because the closed state is not tight, causing the high-speed scouring of the medium. 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 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 not more than 350kg. The imported electric globe valve generally adopts the way of medium entering from above. The disadvantage of media entry from above is just the opposite of that from below.
5. Compared with the gate valve, the advantages of the globe valve are simple structure, good sealing performance, convenient manufacture and maintenance; the disadvantage is that the liquid resistance is large, and the opening and closing force is large. Gate valves and globe valves are fully open and fully closed valves, which are used to cut off or connect the medium, and should not be used as inlet control valves. 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.
