Floating ball valves and fixed ball valves exhibit numerous disparities in terms of structure, performance, and application scenarios, each tailored to distinct working conditions.
Structure and Working Principle
The ball of a floating ball valve remains in a floating state. Under the influence of medium pressure, the ball can displace to a certain extent and press against the sealing seat at the outlet end, thereby creating a seal. This type of ball valve features a straightforward structure, with the ball connected to the exterior solely via the valve stem, which renders installation and maintenance relatively uncomplicated. In contrast, the ball of a fixed ball valve is secured by bearings at both the upper and lower ends, preventing any displacement. When medium pressure acts on the ball, the bearings bear the load, and sealing is accomplished by the sealing seats mounted on either side of the ball. These sealing seats can closely conform to the ball's surface under the action of medium pressure or spring force.
Sealing Performance
Owing to the floating nature of the ball, floating ball valves can achieve excellent sealing performance under medium - and low - pressure conditions, particularly for small - diameter valves. However, under high - pressure scenarios, the ball may deform due to the pressure, potentially resulting in a decline in sealing effectiveness. Conversely, since the ball of a fixed ball valve is stationary, the sealing seat can exert a greater pre - tightening force. Moreover, under high - pressure conditions, the medium pressure further enhances the sealing effect. As a result, in high - pressure and large - diameter pipeline systems, fixed ball valves have a distinct advantage in terms of sealing performance, effectively preventing medium leakage.
Operating Torque and Service Life
The operating torque of floating ball valves is relatively low. This is because the ball aids in sealing under the action of medium pressure, requiring less external force for opening and closing, thus enabling easier operation. Nevertheless, due to the prolonged friction between the ball and the sealing seat, both components are susceptible to wear during frequent operation or in high - pressure environments, which can shorten the service life. In comparison, fixed ball valves generally have a higher operating torque due to the greater pre - tightening force exerted by the sealing seat on the ball. However, the fixed position of the ball reduces the relative sliding between the ball and the sealing seat, leading to lower wear rates. Consequently, fixed ball valves have a longer service life in high - pressure, high - flow, and long - term stable operating conditions.
Applicable Scenarios
Floating ball valves are commonly employed in medium - and low - pressure fluid delivery systems, such as those for water and natural gas, as well as in applications where there are strict requirements regarding valve size, cost, and ease of operation, including water supply and drainage systems in civil buildings and small - scale gas pipelines. Fixed ball valves, on the other hand, are suitable for industrial pipeline systems characterized by high pressure, large diameters, and stringent sealing requirements, such as those in the petroleum, chemical, and long - distance pipeline sectors. For instance, in crude oil pipelines on offshore oil platforms and long - distance natural gas transmission mainlines, fixed ball valves ensure the safe and stable operation of the system while minimizing the risk of medium leakage.
