Views: 0 Author: J-VALVES Publish Time: 2024-12-05 Origin: Site
In industrial pipeline systems, flange globe valves and flange gate valves are two common types of valves. They both play significant roles in controlling the flow of fluid media, yet each possesses unique functional characteristics.
Comprises components such as the valve body, valve disc, valve stem, sealing packing, and handwheel. The valve body is generally cylindrical, with flange plates at both ends for connection to pipelines. The valve disc moves vertically along the center line of the valve seat, controlling the on-off of the medium through the contact and separation of the valve disc and the valve seat.
Consists of the valve body, gate, valve stem, sealing device, etc. The valve body is also cylindrical, with flanges at both ends for pipeline connection. The gate moves up and down in a direction perpendicular to the center line of the passage, opening or closing the passage.
1. When the handwheel is rotated to raise the valve stem, the valve disc leaves the valve seat, allowing the medium to pass through;
2. Conversely, when the valve stem is lowered, the valve disc presses against the valve seat, cutting off the medium flow. The sealing surface between the closing part (valve disc) and the valve seat is a conical surface or a plane, and the sealing force is achieved by the axial pressure of the valve stem.
1. When opening, the gate rises, fully opening the passage with low fluid resistance;
2. When closing, the gate descends and contacts with the sealing surface of the valve seat, preventing the medium from passing through. The sealing surface of the gate valve is usually a parallel plane, and the sealing is accomplished by the compression between the gate and the valve seat.
The flow passage of the globe valve is relatively tortuous. When the medium flows within the valve, a relatively large pressure drop occurs. Especially at a small opening, the flow change is more sensitive to the opening change, providing better regulating performance. It is suitable for more precise flow control. However, under large flow conditions, the pressure loss is relatively large.
The flow passage of the gate valve is relatively straight, with low fluid resistance. There is almost no pressure loss in the fully open state, and the flow is large. However, its flow characteristics are not ideal at a small opening, and the regulating accuracy is poor. It is generally used as a shut-off valve in the fully open or fully closed position.
The sealing surface of the globe valve is a combination of a conical surface or a plane and a conical surface. The sealing force can be precisely controlled by adjusting the valve stem. In the closed state, it can offer good sealing performance and is applicable to medium and low pressure pipeline systems with high sealing requirements, such as fluid transmission pipelines in some chemical and light industries.
The sealing surface of the gate valve is a plane, and the sealing mainly depends on the compression between the gate and the valve seat. When closing, if there are impurity particles in the medium, it may affect the sealing effect. But for clean media, its sealing performance can meet the requirements under normal working conditions. It is commonly used in large-diameter, medium and low pressure water supply and drainage pipeline systems.
It is suitable for small and medium-diameter pipelines transporting media such as water, steam, and oil products. It performs well in situations where frequent flow or pressure regulation is needed, such as steam flow regulation in a thermal system and liquid flow control in chemical production. However, due to its structural characteristics, it is not suitable for media containing a large amount of solid particles or impurities to avoid damaging the sealing surface.
It is more suitable for large-diameter pipelines, such as those in urban water supply and sewage treatment plants. It is mainly used to cut off the fluid and has high reliability in the fully open or fully closed state. For media containing a small amount of impurities, the gate valve has a certain tolerance compared with the globe valve. But if there are too many impurities, it may still affect its normal operation.
The opening and closing stroke of the valve stem of the globe valve is relatively short, making the operation relatively effortless. The handwheel can be rotated a few times to achieve complete closing or opening. However, during the closing process, due to the friction characteristics of the sealing surface, a certain torque needs to be applied; otherwise, the sealing may not be tight.
The opening height of the gate of the gate valve is relatively high, especially for large-diameter gate valves. A large operating space is required when opening. When operating, the handwheel needs to be rotated many times, but the operating force is relatively small in the fully open or fully closed position. However, in the half-open state, due to the uneven force on the gate, vibration and water hammer may occur, which can affect the service life of the valve and the stability of the pipeline system.
In conclusion, both flange globe valves and flange gate valves have their own advantages and disadvantages. In actual selection, it is necessary to comprehensively consider various factors such as the pressure conditions, flow requirements, medium characteristics, and the requirements for sealing and operation convenience of the pipeline system, so as to determine the most suitable valve type to ensure the stable, safe and efficient operation of the pipeline system.
