The function and principle of ball valves

I. Main Function 

Pipeline on/off function: The most basic function. Fully open to allow the medium to pass through, and fully close to cut off the pipeline, blocking the flow of fluids such as water, gas, and oil. 

Flow diversion transportation: The internal direct flow channel has extremely low resistance, ensuring high flow rate and low loss transportation. It is mostly used for main pipelines and transportation trunk lines. 

Work condition isolation: During maintenance or segmental pipeline inspection, the ball valve is closed to isolate the local pipeline, facilitating the construction process without affecting the overall system. 

Emergency shut-off: In gas, water supply and drainage pipelines, it can be quickly turned off to deal with emergencies such as leaks and abnormalities. 

Additional note: Ordinary ball valves are not suitable for long-term partial opening for throttling. The partial open state will wash away the sealing surfaces, which can easily lead to sealing failure. 

II. Working Principle 

The core component of the ball valve is a spherical valve core with a central through-hole. It is combined with the valve seat, valve stem, handle / actuator to form a whole. 

The handle (or electric or pneumatic device) rotates the valve stem, which in turn drives the internal spherical valve core to rotate synchronously. 

The valve core can be rotated by 90° to complete the opening and closing operation: When the through-hole of the ball body is aligned with the direction of the pipeline, the pipeline is completely connected; after rotating 90°, the solid part of the ball body blocks the pipeline, achieving a complete closure. 

The sealing is achieved by the close contact between the surface of the sphere and the valve seats on both sides, and the leakage of the medium is blocked by the contact of the spherical surfaces.