English Views: 0 Author: Miss Lin Publish Time: 2024-07-17 Origin: Site
Ball valve is an important type of valve, which mainly achieves opening and closing by rotating the ball 180 ° around the axis of the valve stem. The common types of ball valves are as follows:
Structural characteristics
The ball of a floating ball valve is floating. Under the pressure of the medium, the sphere can produce a certain displacement and be tightly pressed against the sealing surface at the outlet end, ensuring the sealing of the outlet end. This type of valve has good sealing performance because the ball can automatically adjust its position on the sealing surface to adapt to pressure changes.
Its structure is relatively simple, usually composed of main components such as valve body, sphere, sealing ring, valve stem, etc. Valve bodies are generally made using casting or forging processes, with materials such as cast iron, cast steel, stainless steel, etc., to meet the requirements of different media and pressures.
Working principle
When the valve is in the closed state, the medium pressure will cause the ball to tightly press against the sealing surface at the outlet end. When the valve is opened, the valve stem drives the ball to rotate, and the through-hole on the ball aligns with the channel on the valve body, allowing the medium to pass through. This type of valve can be operated manually, electrically, or pneumatically in various ways.
Applicable scenarios
Floating ball valves are suitable for medium and low-pressure pipeline systems. For example, in some chemical pipelines that transport less corrosive liquids such as hydrochloric acid (with lower concentration) and other media, floating ball valves can effectively cut off the media. It can also be used in pipeline systems for common media such as water and oil, with a working pressure generally ranging from PN1.6 to PN4.0 MPa.
Structural characteristics
The ball of the fixed ball valve is fixed and cannot produce displacement. It is usually equipped with bearings on the upper and lower shafts of the sphere, with low operating torque, suitable for high-pressure and large-diameter valves. The structure of this type of valve is relatively complex, in addition to the basic components such as the valve body, sphere, and stem, there is also a specialized bearing support system.
To ensure sealing performance, fixed ball valves generally adopt a spring preloaded sealing structure. There is a spring that applies pre tension between the sealing ring and the sphere, keeping the sealing ring in close contact with the sphere at all times.
Working principle
During the opening and closing process, the position of the sphere is fixed, and the rotation of the valve stem drives the rotation of the sphere to achieve the on/off of the medium. Due to the fixed shape of the sphere, its sealing performance mainly depends on the pre tightening force of the sealing ring and spring to ensure. Even under high pressure, it can maintain a good sealing state.
Applicable scenarios
Fixed ball valves are mainly used in high-pressure, large-diameter pipeline systems. For example, in oil and gas pipelines, it is used to transport media such as natural gas and crude oil. Due to its strong ability to withstand pressure, it can be used in pipeline systems with working pressures of PN10.0MPa and above. Fixed ball valves are also a common choice in large industrial facilities, such as high-pressure reactor feed pipelines in large refineries.
Structural characteristics
The ball of an elastic ball valve is elastic. The ball and valve seat sealing ring are both made of elastic materials such as polytetrafluoroethylene (PTFE). This material has good corrosion resistance and self-lubricating properties. When closed, the sphere is pressed against the valve seat by the medium pressure, causing elastic deformation and achieving sealing.
Its structure is relatively compact, with excellent sealing performance and the ability to achieve zero leakage. The valve body material is generally cast steel or stainless steel to adapt to different media and temperature environments.
Working principle
When the valve is closed, the pressure of the medium causes the ball to press tightly against the valve seat, causing elastic deformation of the ball and filling the gap between the valve seat and the ball, preventing the medium from leaking. When opened, the valve stem drives the ball to rotate, and the ball returns to its original state, allowing the medium to pass smoothly. The operating torque of this valve is relatively small because the friction coefficient of the elastic material is low.
Applicable scenarios
Elastic ball valves are mainly suitable for occasions that require strict sealing performance. For example, in the pipeline system of the food processing industry, it is used to transport food grade liquids such as milk and juice. Due to its ability to achieve zero leakage, it can ensure the quality and safety of food. In the pharmaceutical industry, such as purified water pipelines and drug delivery pipelines, elastic ball valves are also an ideal valve choice, with working pressures generally ranging from PN1.6 to PN6.4 MPa.
