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The difference between the globe valve and the gate valve

The gate valve is a handwheel that rotates and the stem moves up. The flow rate is different, the gate valve is required to be fully open, and the shut-off valve is not. The gate valve has no import and export direction requirements, and the shut-off valve has the specified import and export! Gate valves and globe valves are shut-off valves and are the two most common valves.
From the appearance, the gate valve is shorter and higher than the shut-off valve, especially the bright-rod valve requires a high 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 not leaking. The wedge of the wedge gate valve is generally 3 to 6 degrees, and the spool that is forced to close excessively or has a large temperature change is easily stuck. Therefore, the high-temperature, high-pressure wedge gate valve has taken certain measures to prevent the valve core from being stuck in the structure. When the gate valve is opened and closed, the sealing surface of the valve core and the valve seat always contact and rub against 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 the rear of the valve core is large, and the sealing surface wear is more serious. .
Compared with the stop 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 both directions. The disadvantage is that the structure is complicated, the height is large, and the sealing surface is easy to wear. The sealing surface of the shut-off valve must be applied with a forced closing valve to achieve the seal. Under the same caliber, working pressure and the same driving device, the driving torque of the shut-off valve is 2.5~3.5 times of the gate valve. This should be noted when adjusting the torque control mechanism of the electric valve.
The sealing faces of the shut-off valves are only in contact with each other when they are completely closed, and the relative slippage of the forcibly closed spool and the sealing surface is small, so that the wear of the sealing faces is also 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 due to the tightness of the closed state, resulting in high-speed flushing of the medium.
When the globe valve is installed, the medium can enter from the bottom of the spool and enter from above. The advantage of the medium entering from below the valve plug is that the packing is not under pressure when the valve is closed, the service life of the packing can be extended, and the packing can be replaced under the condition that the pipe is under pressure. The disadvantage of the medium entering from the lower side of the valve core is that the driving torque of the valve is relatively large, about 1.05~1.08 times of the upper entry, the axial force of the valve stem is large, and the valve stem is easy to bend. For this reason, the medium enters the mode from below, and is generally only applicable to a small-diameter manual shut-off valve, and the force of the medium acting on the valve core when the valve is closed is not more than 350 kg. Electric globe valves generally use a medium to enter from above. The disadvantage of the way the medium enters from above is exactly the opposite of the way it enters below.
Compared with the gate valve, the cut-off valve has the advantages of simple structure, good sealing performance and convenient manufacturing and maintenance; the disadvantage is that the liquid resistance is large, and the opening and closing forces are large. The gate valve and the globe valve are full-open and fully-closed valves. They are not suitable as regulators for shutting off or turning on the medium.

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