What are the difference between globe valves and gate valves？

Globe valves, gate valves, butterfly valves, check valves and ball valves are all indispensable control components in various piping systems. Each valve is different in appearance, structure, and even function. However, the globe valve and the gate valve have some similarities in appearance, and both have the function of cutting off in the pipeline, so there will be many people who do not have much contact with the valve are confused about the two. In this passage, we will briefly talk about the difference between the two.

Structure Difference

The structure of the gate valve will be more complicated than the globe valve. From the appearance, the gate valve is higher than the globe valve and the globe valve is longer than the gate valve under the same caliber. In addition, the gate valve is divided into bright and dark rods while globe valve is not.

Working Principle

When the globe valve is opened and closed, the valve stem is raised, that is, when the handwheel is turned, the handwheel will rotate and lift along with the valve stem. The gate valve rotates the hand wheel to make the valve rod move up and down, and the position of the hand wheel does not change. The flow varies, and gate valves require full opening or full closing, while globe valves do not. Globe valves have prescribed inlet and outlet directions while gate valves do not have inlet and outlet direction requirements.

In addition, the gate valve has only two states of fully open or fully closed, and the stroke of the gate opening and closing is large, and the opening and closing time is long. The travel of the valve plate of the globe valve is much shorter, and the valve plate of the globe valve can be stopped somewhere during the movement for flow adjustment. The gate valve can only be used for cut-off use and has no other functions.

Performance Difference

The globe valve can be used for both shut-off and flow adjustment. The fluid resistance of the globe valve is relatively large, and it is more laborious to open and close, but because the distance between the valve plate and the sealing surface is short, the opening and closing stroke is short.

When it is fully opened, the medium flow resistance in the valve body channel is almost 0, so the opening and closing of the gate valve will be very labor-saving, but the distance between the gate and the sealing surface is long, and the opening and closing time is long.

Installation and Flow Direction

The gate valve has the same effect in both directions. There is no requirement for the direction of the inlet and outlet, and the medium can flow in both directions. The globe valve needs to be installed in strict accordance with the direction indicated by the arrow on the valve body. There is also a clear stipulation on the direction of the inlet and outlet of the globe valve.

There are two ways for the globe valve during installation. One is that the medium can enter from under the valve core. The advantage is that when the valve is closed, the packing is not under pressure, which can extend the service life of the packing, and can bear pressure in the pipeline in front of the valve. Under the circumstances, the replacement of packing is performed. The disadvantage is that the driving torque of the valve is large, which is about 1 times of the upper flow, the axial force on the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only applicable to small-diameter globe valves, and globe valves above DN200 use the method of medium flowing from above. The disadvantage of the medium to enter from above is exactly the opposite of the way to enter from below.

Seal

The sealing surface of the globe valve is a small trapezoidal side of the valve core. Once the valve core is detached, it is equivalent to the valve closing. The gate valve is sealed by the side of the valve core. The sealing effect is not as good as that of the globe valve. And if the valve core falls off, it is not closing the valve like a globe valve.

After introducing five aspects of difference between gate valves and globe valves, I hope you can learn more about them.