Ball Float:

The ball float method is a direct reading liquid level mechanism. The most important practical design for the float is a hollow metal ball or sphere. Therefore, there are no restrictions to the shape, size, or material used. A design consists of a ball float attached to a rod that in turn is linked to a rotating shaft that denotes level on a calibrated scale show in the figure. The operation of the ball float is simple. The ball floats on top of the liquid inside the tank. The float will follow and change the position of the pointer attached to the rotating shaft if the liquid level changes.

Figure: Ball Float Level Mechanism

The travel of the ball float is limited through its design to be inside ±30 degrees from the horizontal plane those results in optimum response and the performance. The actual level range is determined by the length of the connecting arm.

A stuffing box is incorporated to form a water-tight seal around the shaft to avoid leakage from the vessel.