The difference between the stop valve and the gate valve-jlsvalve.com

The difference between the stop valve and the gate valve

1, the structure is different

The gate valve is more complex than the stop valve and has a large height. The gate valve is shorter and higher than the shut-off valve. In particular, the open gate valve requires a high height space, which should be noted in the case of limited installation space.

 

2, the sealing surface is different

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 back of the valve core is large, and the sealing surface wear is more serious. 

Once the valve flap of the shut-off valve is in the open state, its valve seat and the valve sealing surface are no longer in contact, so its sealing surface is less mechanically worn, but if the medium contains solid particles, it is easy to damage the sealing surface.

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 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.
The sealing surface of the shut-off valve must be forced to close by the 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 shut-off 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.

3, the flow resistance is different

When the gate valve is fully open, the entire flow passage is straight through. At this time, the pressure loss of the medium operation is the smallest. Compared with the shut-off valve, its main advantage is that the fluid flow resistance is small, and the flow resistance coefficient of the ordinary gate valve is about 0.08~0.12. The drag coefficient of the globe valve is approximately 3.5 to 4.5. The opening and closing force is small. Gate valves are generally suitable for use, do not need to open and close frequently, and keep the ram fully open or fully closed, not suitable for adjustment and throttling. The flow resistance of the shut-off valve is large throughout the stroke, the unbalanced force is large, and the required driving force or torque is correspondingly much larger. However, it is well suited for use as a conditioning and throttling fluid.

 

4, the flow is different

When the shut-off 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 pressure in front of the valve. The disadvantage of the medium entering from the bottom 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. To this end, the medium enters the mode from below, generally only for small-diameter shut-off valves (below DN50), and the shut-off valves above DN200 use the medium to flow from above. Electric shut-off 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. The flow direction of the gate valve is the same from both sides.

 

5, different itinerary

The stroke of the gate valve is larger than that of the shut-off valve.

 

6, the maintenance process is different

The maintenance of the gate valve is not suitable for on-site pipelines, and the valve seat and disc of most of the shut-off valves can be replaced online without removing the entire valve from the pipeline. This is where the valve and pipeline are welded together. It is very suitable.

 

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