When the pressure reaches a certain level, the ball drifts downstream and tightly pushes against the seat. The seat must be made of strong materials because it bears the force of the pressure when the ball comes into contact with it. Floating ball valves are constructed from stainless steel, brass or other metals.
The ball inside may have a ceramic center and is usually coated in chrome. Floating ball valves are used to provide shut-off abilities in low or moderate pressure applications. They are used in many different industries that use pipes for transporting fluids especially in the chemical, pharmaceutical and water management industries.
Floating ball valves are identical to conventional ball valves in design and function with one major exception. Like their counterparts, floating ball valves have a ball with a hole bored straight through the center. The current flows through this passageway until the ball rotates, making a quarter turn and blocking the pipe because the hole is perpendicular to the direction of the flow. The ball is rotated through use of a stem or shaft that connects the ball to the actuator.
This can be a lever, hand wheel or electric motor. Floating ball valves are different in that the ball floats very slightly downstream to come into contact with the downstream seat, which is where the primary sealing occurs. When the pressure of the gas, liquid or liquid-solid mixture is low, the ball makes slight contact with the sealing ring.
The liquid flows through the hole in the ball mostly uninhibited. As the pressure grows, the force of the flow pushes the ball into the seat and the contact area increases. Once the actuator is engaged, the ball quickly rotates to hide the hole, thus blocking off the rest of the pipe. Despite the name of the valve, the distance the ball moves is very small and is only able to move along the axis of the pipe.