1. Structure
In the case of limited installation space, it should be noted that the gate valve can rely on the medium pressure to tightly close the sealing surface, so as to achieve the effect of no leakage. When opening and closing, the valve core and the sealing surface of the valve seat are always in contact and rubbing against each other, so the sealing surface is easy to wear, and when the gate valve is close to closing, the pressure difference between the front and rear of the pipeline is very large, which makes the sealing surface wear more serious.

2. Working Principle
When the valve is turned off and closed, the valve is rising. That is to say, when the handwheel is rotated, the hand wheel will follow the valve stem to rotate and lift and lift. The position itself is unchanged. The traffic is different. The gate valve is required to be fully opened or completely off, and the deeper valve is not required. The deadline valve has the prescribed import and export direction;

In addition, there are only two states: full or full -level. The schedule of the gate is very large, and the opening time is long. In a certain place, the traffic adjustment is used. The gate valve can only be used for interception, without other functions.

3. Performance Different
Globe valve can be used not only for cutting off, but also for flow regulation. The fluid resistance of cut-off valve is relatively large, and it is difficult to open and close, but the distance between valve plate and sealing surface is short, so the opening and closing stroke is short.

Because the gate valve can only be fully opened and closed, when it is fully opened, the medium flow resistance in the valve body channel is almost zero, so the opening and closing of the gate valve is very labor-saving, but the gate is far from the sealing surface and takes a long time to open and close.

4. Installation and Flow

The flow direction of gate valve is the same in both directions, and the installation does not require the direction of import and export, so the medium can flow in both directions. The globe valve should be installed in strict accordance with the direction marked by the arrow of the valve body, and the flow direction of globe valve should be from top to bottom.

The globe valve is low into the high, from the outside view there is an obvious pipe is not a level line. The gate valve channel is in a horizontal line. The travel of the gate valve is larger than that of the Globe Valve.

From the point of view of flow resistance, the flow resistance of gate valve is small when it is fully opened, but that of stop valve is large. The flow resistance coefficient of ordinary gate valve is about 0.08~0.12, and the opening and closing force is small, so the medium can flow in two directions. The flow resistance of ordinary stop valve is 3-5 times that of gate valve. It needs to be forcibly closed when it is opened and closed to achieve sealing, and the valve core of stop valve only touches the sealing surface when it is completely closed, so the wear of the sealing surface is very small. Because the main flow force is large, the Globe valve with actuator should be added.

There are two ways to install the globe valve. One is that the medium can enter from below the valve core, which has the advantage that the packing is not under pressure when the valve is closed, which can prolong the service life of the packing, and the packing can be replaced when the pipeline in front of the valve is under pressure. Disadvantages are that the driving torque of the valve is large, which is about 1 time of the upward inflow, the axial force on the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only suitable for small-caliber globe valves (below DN50), and the globe valves above DN200 all adopt the way of medium inflow from above. (Electric globe valves generally adopt the way of medium inflow from above.) The disadvantage of medium inflow from above is just the opposite to that from below.
5. Seal
The sealing surface of the globe valve is a small trapezoidal side of the valve core (depending on the shape of the valve core). Once the valve core falls off, it is equivalent to closing the valve (if the pressure difference is large, it will certainly not be closed tightly, but the check effect is not bad). The gate valve is sealed by the side of the valve core gate, so the sealing effect is not as good as that of the globe valve, and the valve core falling off will not be equivalent to closing the valve like the globe valve.