IDENTIFY the principle of operation of the following types of level instrumentation
Dip Tube (Bubbler) Level Detector
In the gauge glass method, a transparent tube is attached to the bottom and top (top connection not needed in a tank open to atmosphere) of the tank that is monitored. The height of the liquid in the tube will be equal to the height of water in the tank.
The operation of the ball float is simple. The ball floats on top of the liquid in the tank. If the liquid level changes, the float will follow and change the position of the pointer attached to the rotating shaft.
The operation of the chain float is similar to the ball float except in its method of positioning the pointer and its connection to the position indication. The float is connected to a rotating element by a chain with a weight attached to the other end to provide a means of keeping the chain taut during changes in level.
The dip tube is a vertical pipe connected through the side of a tank at the bottom. An air pressure supply is connected to the pipe, and a constant airflow displaces the water in the pipe. The pressure required to displace the water in the vertical pipe is equal to the hydrostatic pressure due to the liquid level in the tank.