Bronze globe valve - how it works?

Globe valve, also known as cut-off valve, is a mandatory sealing valve. So when the valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters the valve from under the valve disc, the resistance that the operating force needs to overcome is the friction force between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve stem The diameter of the valve should be large, otherwise the failure of the top of the valve stem will occur. 

According to the connection method, it is divided into three types: flange connection, thread connection and welding connection. After the appearance of the self-sealing valve, the medium flow direction of the globe valve is changed from the top of the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, but the force to open the valve is large, and the diameter of the valve stem can be adjusted accordingly. decrease. 

At the same time, under the action of the medium, this form of valve is also tighter. my country's valve "Three Chemicals" once stipulated that the flow direction of the globe valve should be from top to bottom. When the globe valve is opened, the opening height of the valve disc is 25% to 30% of the nominal diameter. The flow rate has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the globe valve should be determined by the stroke of the valve disc.

The opening and closing part of the stop valve (Globe Valve) is a plug-shaped valve disc. The movement form of the valve stem, (common name: dark rod), also has a lifting and rotating rod type, which can be used to control various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. flow. Therefore, this type of shut-off globe valve is very suitable for shut-off or regulation and throttling. Because the valve stem of this type of valve has a relatively short opening or closing stroke, and has a very reliable cut-off function, and because the change of the valve seat port is proportional to the stroke of the valve disc, it is very suitable for flow regulation.

Hydraulic globe valve working principle

The globe valve, also known as the cut-off valve, is one of the most widely used valves. The reason why it is popular is that the friction between the sealing surfaces during the opening and closing process is small, it is more durable, the opening height is not large, and it is easy to manufacture. , easy maintenance, not only suitable for medium and low pressure, but also suitable for high pressure. The closing principle of the globe valve is to rely on the pressure of the valve stem to make the sealing surface of the valve disc and the sealing surface of the valve seat closely fit to prevent the flow of the medium. my country's valve "Three Chemicals" once stipulated that the flow direction of the globe valve shall be from top to bottom, so there is directionality during installation. The structure of the globe valve is longer than that of the gate valve, and at the same time, the fluid resistance is large, and the sealing reliability is not strong during long-term operation.

As one of the most important shut-off valves, the globe valve plays an important role in the aerospace field. As an important component of aerospace equipment, globe valve realizes the functions of medium conveying, cutoff and adjustment, and its sealing performance directly affects the safe and reliable operation of aerospace equipment. The study of the influencing factors and influence rules of the sealing characteristics of typical globe valves has guiding significance for the structural design of the valve sealing pair, thereby improving the sealing performance and reliability of the valve.

Actuated globe valve characteristic

The valve plays an important role in cutting and throttling the medium in the pipeline where it is located. As an extremely important cut-off valve, the valve is sealed by applying torque to the valve stem, and the valve stem moves upward in the axial direction. The disc applies pressure to make the sealing surface of the disc and the sealing surface of the valve seat closely fit, preventing the medium from leaking along the gap between the sealing surfaces. The sealing pair of the globe valve is composed of the sealing surface of the valve disc and the sealing surface of the valve seat, and the valve stem drives the valve disc to move vertically along the center line of the valve seat.  

During the opening and closing process of the globe valve, the opening height is small, it is easy to adjust the flow, and it is convenient to manufacture and maintain, and the pressure is applicable to a wide range. Compared with another commonly used shut-off valve in industrial production, the one-by-one valve, the shut-off valve is simpler in structure and easier to manufacture and maintain. 

In terms of service life, the sealing surface of the globe valve is not easy to be worn and scratched, and there is no relative sliding between the valve disc and the sealing surface of the seat during the valve opening and closing process, so the wear and scratches on the sealing surface are small, so the sealing performance is improved. In the process of full closing, the valve disc stroke is small, and its height is smaller than that of the noisy valve. The disadvantage of the globe valve is that the opening and closing torque is large and it is difficult to achieve rapid opening and closing. Because the flow channel in the valve body is relatively tortuous, the fluid flow resistance is large, resulting in a large loss of fluid power in the pipeline.