Welded stop valve And gate valve difference
It works differently, Globe valve It is a rising stem type, and the handwheel rotates and rises with the stem. The gate valve is the handwheel rotation, the stem does the rising movement. The flow rate is different, the gate valve is required to be fully open, and the stop valve is not. The gate valve has no inlet and outlet direction requirements, and the stop valve has specified inlet and outlet!
Gate valve and globe valve are shut-off valves, which are two common valves.
From the appearance, gate valve is shorter and higher than globe valve, especially rising stem valve needs higher height space. The sealing surface of gate valve has certain self sealing ability, and its valve core closely contacts with the sealing surface of valve seat by medium pressure, so as to achieve tight sealing. Wedge gate valve core slope is generally 3 ~ 6 degrees, when forced to close excessive or temperature change is large, the spool is easy to be stuck. Therefore, high temperature, high pressure wedge gate valve, in the structure have taken certain measures to prevent the valve core from sticking. When the gate valve is opened and closed, the sealing surface of the valve core and the valve seat always contact and rub 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 wear of the sealing surface is more serious.
Compared with the stop valve, the main advantage of gate valve is that the fluid flow resistance is small. The flow resistance coefficient of ordinary gate valve is about 0.08 ~ 0.12, while that of ordinary stop 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 sealing surface is complex in height and easy to be worn. Under the same caliber, working pressure and the same driving device, the driving torque of the stop valve is 2.5 ~ 3.5 times of that of the gate valve. This point should be paid attention to when adjusting the torque control mechanism of electric valve.
The sealing surfaces of the globe valve only contact each other when they are completely closed. The relative slip between the forced closing spool 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 stop valve is mostly due to the debris in front of the valve core and the sealing surface, or due to the loose closing state, resulting in high-speed erosion of the medium.
The medium can enter from the bottom of the valve core and can enter from the top. The advantage of the medium entering from the lower part of 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 under the pressure of the pipe in front of the valve. The disadvantage of medium entering from the lower part of the valve core is that the driving torque of the valve is large, which is about 1.05 ~ 1.08 times of that from the upper part. The axial force on the valve stem is large and the valve stem is easy to bend. Therefore, the medium entering from the bottom is generally only applicable to small caliber manual stop valve, and the force of medium acting on the valve core is not more than 350 kg when the valve is closed. Electric stop valve Generally, the medium enters from above. The disadvantage of media entry from the top is just the opposite of that from the bottom.
Compared with gate valve, the globe valve has the advantages of simple structure, good sealing performance and convenient manufacturing and maintenance; the disadvantages are large liquid resistance and large opening and closing force. Gate valve and globe valve belong to full open and full close type valves, which are used to cut off or connect medium, and should not be used as medium Regulating valve use.
The application range of globe valve and gate valve is determined according to its characteristics. In small channels, when better shut-off tightness is required, globe valves are often used; in steam pipelines and large-diameter water supply pipelines, gate valves are used because of the low requirement of fluid resistance.