1. Gate valve
Gate valve, also called gate valve, is a widely used valve. Its closing principle is that the sealing surface of the gate and the sealing surface of the valve seat are highly smooth, flat and consistent. They are mutually attached to prevent the medium from flowing through, and rely on the shape of the top mold, spring or gate to enhance the sealing effect. It mainly cuts off in the pipeline.
Its advantages are: small fluid resistance, easy opening and closing, can be used in the case of two-way flow of the medium, no directionality, the sealing surface is not easy to be eroded when fully opened, and the structure length is short. It is not only suitable for small valves, but also suitable for making Big valve.
Gate valves are divided into two types according to the thread of the valve stem, one is the exposed stem type, and the other is the concealed stem type. According to the gate structure, there are two types, one is parallel, and the other is mode.
2. Globe valve
The stop valve, also called the cut-off valve, is the most widely used valve. The reason why it is so popular is that the friction between the sealing surfaces during the opening and closing process is small, it is relatively durable, the opening height is not large, the manufacturing is easy, and the maintenance Convenient, not only suitable for medium and low pressure, but also suitable for high pressure.
Its closing principle is to rely on the pressure of the valve stem to make the disc sealing surface and the valve seat sealing surface closely fit to prevent the medium from flowing.
The shut-off valve only allows the medium to flow in one direction and is directional when installed. Its structural length is longer than that of the gate valve, and the fluid resistance is large, and the reliability of the seal is not strong during long-term operation.
There are three types of globe valves: straight-through, right-angle and direct-flow oblique globe valves.
3. Butterfly valve
The butterfly valve is also called the butterfly valve. As the name implies, its key components are like a butterfly facing the wind and turning freely.
The disc of the butterfly valve is a disc, which rotates around an axis in the valve seat. The size of the rotation angle is the opening and closing degree of the valve.
Butterfly valve has the characteristics of light weight, saves material than other valves, simple structure, quick opening and closing, both cut-off and throttling can be used, fluid resistance is small, and operation is labor-saving. The butterfly valve can be made into a large diameter. Where a butterfly valve can be used, it is best not to use a gate valve, because a butterfly valve is more economical than a gate valve and has better adjustability. Currently, butterfly valves are widely used in hot water pipelines.
4. Ball valve
The working principle of the ball valve is to make the valve unblocked or blocked by rotating the valve. The ball valve switch is light, small in size, can be made into a large diameter, reliable sealing, simple structure, convenient maintenance, the sealing surface and the spherical surface are often in a closed state, and it is not easy to be eroded by the medium. It is widely used in various industries.
There are two types of ball valves, one is floating ball type, and the other is fixed ball type.
5. Stopcock
The plug valve relies on the plug body to rotate around the center line of the valve body to achieve the purpose of opening and closing. Its function is to cut off, divide the field and change the flow direction of the medium. Simple structure, small size, only need to rotate 90 degrees during operation, and the fluid resistance is not large. The disadvantage is that the switch is laborious, the sealing surface is easy to wear, and it is easy to get stuck at high temperature, which is not suitable for adjusting the flow rate.
The cock valve is also called the cock, the Cock, and the heart-rotating door. There are many types of it, including straight-through, three-way and four-way.
6. Check valve
The check valve is a valve that automatically opens and closes by the power of the fluid itself. Its function is to prevent the medium from flowing back. It has many names, such as check valve, check valve, check valve and so on. According to the structure, it can be divided into two categories.
(1) Lifting type: The disc moves along the vertical centerline of the valve body. There are two types of this kind of check valve: one is horizontal, installed in horizontal pipeline, the shape of the valve body is similar to that of globe valve, and the other is vertical, installed in vertical pipeline.
(2) Swing type: The valve flap rotates around the pin shaft outside the seat. This type of valve has single flap, double flap and multiple flaps, but the principle is the same.
The suction bottom valve of the water pump suction pipe is a deformation of the check valve. Its structure is the same as the above two types of stop valves, except that its lower end is open to allow water to enter.