The sealing performance of ball valves is affected by various factors, and the following are some of the main factors:

1、 Sealing auxiliary material

Hard sealed ball valves adopt a sealing structure between metals, usually using a spring pressed tight cover or mechanical sealing between metals; Soft sealed ball valves use elastic materials for sealing, usually rubber, PTFE and other materials. Hard sealed ball valves have good sealing performance, can withstand media under high temperature and high pressure conditions, and have high corrosion resistance;

The sealing performance of soft sealed ball valves is generally poor and suitable for low temperature, low pressure or general working conditions. Due to the good sealing performance of hard sealed ball valves, the hard double sealing structure is suitable for special working conditions such as high temperature, high pressure, and corrosive media, such as industries such as petroleum and chemical; Soft sealed ball valves are suitable for general working conditions, such as pipeline systems for tap water, natural gas, etc

2、 Processing accuracy
Dimensional accuracy: The dimensional accuracy of key components such as the ball and seat of a ball valve directly affects its sealing performance. If the roundness of the ball is not sufficient, the diameter deviation is too large, or the inner diameter of the valve seat is inaccurate, the ball and valve seat may not be able to fit tightly when the ball valve is closed, resulting in leakage.

Surface roughness: The surface roughness of the sealing surface also has a significant impact on the sealing performance. Overly rough surfaces can lead to poor sealing, while excessively smooth surfaces may affect the micro meshing effect between sealing materials. Generally speaking, the surface roughness of the sealing surface should be controlled within an appropriate range to ensure good sealing effect.

3、 Assembly quality
Component installation sequence: If the assembly sequence of the ball valve is incorrect, it may lead to uneven stress and deformation of the components, which in turn can affect the sealing performance. For example, when installing the valve seat, if it is not installed in the prescribed order and method, it may cause the valve seat to be installed improperly or deformed, resulting in poor sealing between the ball and the valve seat.

Pre tightening force control: During the assembly process, the pre tightening force applied to the sealing pair should be moderate. The pre tightening force is too small to ensure a tight fit between the sealing surfaces, which can easily lead to leakage; Excessive pre tightening force may cause excessive wear, deformation, or even damage to the sealing surface, shorten the service life of the ball valve, and affect the sealing performance.

4、 Medium characteristics
Corrosivity: If the medium is corrosive, it will cause corrosion on the sealing surface of the ball valve, resulting in defects such as potholes and pitting, which will damage the flatness and smoothness of the sealing surface, leading to seal failure. For example, in chemical production, media containing strong acids and bases can quickly corrode ordinary metal sealing surfaces.

Temperature and pressure: Changes in the temperature and pressure of the medium can have a significant impact on the sealing performance of ball valves. In high temperature environments, the performance of sealing materials may change, such as a decrease in hardness, a decrease in elastic modulus, etc., resulting in a decrease in sealing force; In high-pressure environments, the sealing pressure between the sphere and the valve seat increases. If the sealing material has insufficient compressive strength, it may be crushed and cause leakage.

5、 Operating conditions
Opening and closing frequency: Frequent opening and closing operations will cause the sealing pair of the ball valve to constantly rub and wear. As the number of uses increases, the wear of the sealing surface will gradually intensify, leading to a decrease in sealing performance. For example, in some automated production lines, ball valves need to be frequently opened and closed to control the transportation of materials, which can greatly affect the sealing performance of the ball valves.

Operation speed: The opening and closing speed of the ball valve may also affect the sealing performance if it is too fast or too slow. Excessive opening and closing speed may result in water hammer, causing impact damage to the sealing surface; If the opening and closing speed is too slow, it may cause the sealing surface to remain in a semi open and semi closed state for a long time during the opening and closing process, which is susceptible to erosion and wear by the medium.

6、 Maintenance and upkeep
Regular inspection: Regularly inspect the ball valve to promptly detect issues such as wear and corrosion on the sealing surface, and take corresponding measures for repair or replacement, which can effectively extend the sealing life of the ball valve. If not checked for a long time, the sealing problem may gradually deteriorate, ultimately leading to serious leakage.

Cleaning and lubrication: Keep the interior and sealing surfaces of the ball valve clean, prevent impurities, particles, etc. from entering between the sealing surfaces, and avoid scratching and wear on the sealing surfaces. At the same time, regularly lubricating the valve stem, bearings, and other parts of the ball valve can reduce friction during operation and help maintain good sealing performance of the ball valve.

1、 Drive mode

Manual ball valve:

The opening and closing actions of the ball valve are achieved by manually rotating the valve stem. During operation, the operator directly acts on the handwheel or handle, manually rotates the valve stem, and then drives the ball core to rotate, achieving the purpose of controlling fluid flow.

Pneumatic ball valve:

Using compressed air as the power source, the opening and closing of the ball valve are driven by pneumatic actuators. Pneumatic actuators receive pressure signals from the control system, convert pressure energy into mechanical energy, drive the valve stem and ball core to rotate, and achieve fluid control.

2、 Working principle

Manual ball valve: When the valve stem is manually rotated to align the through-hole of the ball core with the pipeline axis, the valve is fully open and fluid can pass smoothly; When the ball core rotates 90 degrees and the through-hole of the ball core is perpendicular to the pipeline axis, the valve is completely closed, preventing fluid from passing through.

Pneumatic ball valve: After the control system sends the valve opening signal, compressed air enters the air inlet of the pneumatic actuator, pushing the piston or diaphragm and other actuating components to move, driving the valve stem and ball core to rotate 90 degrees, achieving valve opening; When receiving the valve closing signal, the actuator exhausts, and under the action of the spring or other reset device, the valve stem and ball core rotate in the opposite direction by 90 degrees, and the valve closes.

3、 Performance characteristics

Manual ball valve operation is simple and flexible: the structure is relatively simple, and manual operation is convenient and fast. Operators can easily control the opening of the valve according to actual needs. Low cost: Due to the absence of complex driving devices such as pneumatic actuators, the manufacturing and procurement costs of manual ball valves are relatively low. High reliability: Without complex pneumatic or electric control systems, it reduces the risk of failure caused by electrical faults or gas source issues, and has high reliability in some simple working conditions.

4、 Pneumatic ball valve quick response:

Pneumatic actuators have fast response capabilities and can complete the opening and closing of valves in a short period of time, making them suitable for situations that require high switching speeds. High degree of automation: It can be integrated with various automation control systems to achieve remote control and automated operations, facilitating centralized management and monitoring. High output torque: Pneumatic actuators can provide a large output torque, suitable for large-diameter ball valves or ball valves used in high-pressure, high viscosity media and other working conditions, and can easily overcome the resistance when the valve is opened and closed.

5、 Applicable scenarios for manual ball valves and low-pressure small-diameter pipelines:

In some low-pressure, small-diameter pipeline systems, such as household water supply and drainage pipelines, small air conditioning system pipelines, etc., manual ball valves can meet simple on-off control requirements, with low cost and easy operation.

Occasions of infrequent operation:

For some occasions that do not require frequent valve operation, such as certain backup pipelines or occasionally used branch pipelines, the simple and reliable characteristics of manual ball valves make them a suitable choice.
Areas with convenient on-site manual control: In areas where operators can easily access valves for on-site manual control, such as local pipeline systems in small factories, equipment pipelines in laboratories, etc., manual ball valves can quickly achieve on/off operations. Automated production process of pneumatic ball valves: Pneumatic ball valves are widely used in the automatic control of fluid conveying pipelines on automated production lines in industries such as petroleum, chemical, pharmaceutical, and food. They can seamlessly integrate with control systems such as PLC and DCS to achieve automation and intelligence in the production process.
In situations where fast switching is highly required, such as emergency shutdown systems, fire protection systems, gas supply systems, etc., pneumatic ball valves can respond quickly to ensure the safe and reliable operation of the system. Adverse environmental conditions: In some harsh environmental conditions such as high temperature, high pressure, flammability, explosiveness, toxicity, etc., pneumatic ball valves can be remotely controlled to avoid direct contact with hazardous environments by operators and improve operational safety.