1. Different sealing structures
The ball core of the floating ball valve can move along the flow channel, but the valve seat does not move. The ball core of the fixed ball valve cannot move along the flow channel, but the valve seat can move.
The floating ball valve only has an upper stem, and the ball core can move along the direction of the flow channel. The medium pressure pushes the ball core to press the outlet valve seat to achieve one-sided forced sealing.
The ball core of the fixed ball valve has two upper and lower valve stems. The ball core is fixed on the valve body through the upper and lower valve stems. The ball core cannot move along the direction of the flow channel. The valve seat moves to hold the ball core tightly to achieve sealing.
2. Applicable working conditions are different
Float ball valves are mostly used for low pressure and small diameter. When the pressure is too high, the medium pushing the ball core will crush the outlet valve seat and increase the ball valve torque. Fixed ball valves are mostly used for high pressure and large diameter. For example, the West-East natural gas pipeline has a pressure of up to 1500LB and a diameter of DN1500mm. The structure of the valve seat pressing the ball core can reduce the valve seat sealing pressure. Reduce ball valve torque.
3. Different valve seat seals
The fixed ball valve can realize the functions of one-way sealing in front of the valve, one-way sealing behind the valve, two-way sealing in front of the valve, two-way sealing behind the valve, and pressure relief in the middle cavity. Floating ball valves rely on the outlet valve seat to achieve forced sealing.