The Difference between Globe Valves and Gate Valves
We are going to talk about the difference between globe valves and gate valves.
In terms of structure:
The length of gate valves is shorter than that of globe valves, and the height is higher than that of globe valves. We should pay attention to the case of limited installation space. Gate valves can rely on the medium pressure tightly and sealing surface closed, so as to achieve the effect of leakage. When opening and closing, the sealing surface of the valve core and seat always contact and rub against each other, so the sealing surface is easy to wear. When the gate valve is close to closing, the pressure difference between front and rear of the pipeline is large, which makes the sealing surface wear more serious.
In the principle:
The difference between globe valves and gate valves in principle is that the globe valve is a rising stem, and the hand-wheel rotates and rises with the stem. Gate valves are in hand-wheel rotation, and the stem can for upward motion. The flow varies. It requires that the gate valves can be full open or full closed, while globe valves do not. The globe valve has provisions of the import and export direction. Gate valves have no inlet and outlet direction requirements.
From the flow: the flow of the globe valve is low into high. There is an obvious pipeline which is not a phase level line from the outside there. The runner of gate valves is in a horizontal line. The travel of gate valves is larger than that of globe valves.
Explanation:
As for flow resistance, when we fully open the gate valve, the flow resistance is small. When we load the check valve, the flow resistance is large. The flow resistance coefficient of ordinary gate valves is about 0.08~0.12. The opening and closing force is small, and the medium can flow in two directions. The flow resistance of ordinary globe valves is three to five times than that of gate valves. The valve core of the globe valve only touches the sealing surface when it is completely closed, so the wear of the sealing surface is very small. Due to the large flow force, the globe valve with the actuator should be paid attention to the adjustment of the torque control mechanism.
From the installation:
1. As for the flow direction of gate valves, the effect is the same from both sides.
2. There are two ways to install the globe valve. One is that the medium can enter from below the valve core. The disadvantage is that the driving torque of the valve is larger. It is about one time of the flow into the top. The axial force of the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only applicable to small-caliber globe valves (DN50 or below), and the globe valve of DN200 or more needs the way of medium flowing in from the top. (The electric globe valve is generally used from the top of the medium into the way.) The disadvantage of the medium coming in from above is the opposite of the medium coming in from below.
From the sealing surface:
The sealing surface of valve core of globe valves is a small trapezoidal profile (we need to see the shape of the valve core). Once the valve core falls off, it is like valve closing (if the pressure difference is big, the valve can not be closed tightly. Of course, the inverse effect of valves is good instead. The gate valve is sealed on the side of the gate plate of the valve core. The sealing effect is better than that of globe valves.
In terms of structure:
The length of gate valves is shorter than that of globe valves, and the height is higher than that of globe valves. We should pay attention to the case of limited installation space. Gate valves can rely on the medium pressure tightly and sealing surface closed, so as to achieve the effect of leakage. When opening and closing, the sealing surface of the valve core and seat always contact and rub against each other, so the sealing surface is easy to wear. When the gate valve is close to closing, the pressure difference between front and rear of the pipeline is large, which makes the sealing surface wear more serious.
In the principle:
The difference between globe valves and gate valves in principle is that the globe valve is a rising stem, and the hand-wheel rotates and rises with the stem. Gate valves are in hand-wheel rotation, and the stem can for upward motion. The flow varies. It requires that the gate valves can be full open or full closed, while globe valves do not. The globe valve has provisions of the import and export direction. Gate valves have no inlet and outlet direction requirements.
From the flow: the flow of the globe valve is low into high. There is an obvious pipeline which is not a phase level line from the outside there. The runner of gate valves is in a horizontal line. The travel of gate valves is larger than that of globe valves.
Explanation:
As for flow resistance, when we fully open the gate valve, the flow resistance is small. When we load the check valve, the flow resistance is large. The flow resistance coefficient of ordinary gate valves is about 0.08~0.12. The opening and closing force is small, and the medium can flow in two directions. The flow resistance of ordinary globe valves is three to five times than that of gate valves. The valve core of the globe valve only touches the sealing surface when it is completely closed, so the wear of the sealing surface is very small. Due to the large flow force, the globe valve with the actuator should be paid attention to the adjustment of the torque control mechanism.
From the installation:
1. As for the flow direction of gate valves, the effect is the same from both sides.
2. There are two ways to install the globe valve. One is that the medium can enter from below the valve core. The disadvantage is that the driving torque of the valve is larger. It is about one time of the flow into the top. The axial force of the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only applicable to small-caliber globe valves (DN50 or below), and the globe valve of DN200 or more needs the way of medium flowing in from the top. (The electric globe valve is generally used from the top of the medium into the way.) The disadvantage of the medium coming in from above is the opposite of the medium coming in from below.
From the sealing surface:
The sealing surface of valve core of globe valves is a small trapezoidal profile (we need to see the shape of the valve core). Once the valve core falls off, it is like valve closing (if the pressure difference is big, the valve can not be closed tightly. Of course, the inverse effect of valves is good instead. The gate valve is sealed on the side of the gate plate of the valve core. The sealing effect is better than that of globe valves.
