Types and features of piping gate valves
Valves can be divided into gate valves, which allow or stop fluids from flowing, and special-purpose valves, which change the route, divide or combine flows. This time, we will focus on gate valves and introduce their types and features.
Gate valves are classified into several types depending on their structure, but if you do not use a valve that is appropriate for the piping or pump, not only will it not perform to its full capacity, but it may also cause major problems.
Choose the appropriate valve based on its characteristics and install it in a location and method that suits it.
1. What is a piping gate valve?
A valve is a component used to adjust the amount, direction, and pressure of fluid passing through a pipe. Gate valves, also known as sluice valves, have the function of dividing and stopping the flow of fluid within a pipe, or adjusting the width of the flow path to increase or decrease the flow rate.
Typical examples include globe valves, ball valves, gate valves, and butterfly valves.
2. Types and characteristics of piping gate valves
Now, let's take a look at the characteristics of four typical gate valves.
■ ①．Globe valve
Because of their rounded appearance, they are called globe valves, which come from the English word globe, which means spherical.They are also called globe valves, ball valves, needle valves, angle valves, and other names.
While it has the advantages of high shutoff performance and easy flow rate adjustment, it also has the disadvantage of large pressure loss due to narrow sections in the S-shaped flow path.
■ ②．Ball valve
Ball valves, also known as ball valves, control fluid by rotating a ball-shaped valve body with holes.
The flow path is straight in the piping direction, which has the advantage of small pressure loss, but it is not suitable for fine adjustment of flow rate.
Also, depending on specification, there are types with different internal valve piping diameters (bore diameters) even if the connecting piping diameter is the same, so care must be taken when selecting.
■ ③．Gate valve
Gate valves, also known as gate valves, use a plate-shaped valve body to open and close the flow path and control the fluid.
When the valve is fully opened, the valve itself disappears from the flow path, making it an excellent valve in terms of pressure loss. However, when used at an intermediate opening, the valve body vibrates and causes problems, so the flow rate cannot be adjusted and the valve is used at either the fully open or fully closed position.
■ ④. Butterfly valve
Butterfly valves are shaped like a butterfly, with a disk-shaped valve body that rotates inside a short, cylindrical body. They are also called butterfly valves, butterfly valves, or butterfly valves.
Its simple structure means it requires little installation space, making it suitable for use in a variety of locations. It also has the advantage of having little pressure loss and making it easy to adjust the flow rate.
However, due to the structure, the installation direction is fixed, and the valve disc is disc-shaped, so there are disadvantages such as the tendency for water hammer to occur, so care must be taken.
3. How to select and install a gate valve
Gate valves must be selected and installed appropriately to match the piping, pumps, fluids, etc. used in the factory.
■ Select the valve that is best suited to your application
For example, gate valves can be broadly divided into those that are suitable for flow control and those that are not. Ball valves and gate valves are not suitable for flow control, but they have little pressure loss and are excellent as stop valves.
However, globe valves and butterfly valves, which are good at flow control, have drawbacks such as large pressure loss and a tendency to cause water hammer, so be sure to carefully check your company's piping situation before making a selection.
■ Place the flow rate adjustment valve on the discharge side
Normally, flow rate adjustment valves are always installed on the discharge side of the pump. If they are installed on the suction side, the suction pressure to the pump will decrease when the valve is closed, causing bubbles to form in the piping and making it more likely to experience cavitation (cavity phenomenon).
4. Valve installation methods to prevent problems
Valves should generally be the same size as the pipe diameter, but if you choose a globe valve or ball valve, the flow path will be narrower and you may not be able to obtain the calculated flow rate.
In this case, depending on the situation, it may be necessary to increase the overall diameter or use a gate valve that reduces pressure loss.It may also be necessary to take measures such as using a full-bore ball valve that has the same bore diameter (diameter) as the piping size.
Also, when installing valves, be sure to provide maintenance space in advance to ensure ease of daily operation and equipment inspections.
５．まとめ
This time, we explained the types and characteristics of gate valves. The main gate valves include globe valves, ball valves, gate valves, and butterfly valves, and due to differences in their structure, they are suited to different piping and pumps.
Ball valves and gate valves are generally used when minimizing pressure loss, while globe valves and butterfly valves are generally used when precise control of flow rate is required.
Also, depending on the installation location, it may be necessary to increase the diameter or change the valve used depending on the required flow rate.
