Radiation type level measurement. Is non contact type detector which is used where electrical method would not survive.
working principle
1.It consist of gamma ray source holder on one side of the tank and a gamma detector on the other side of the tank.
2. The gamma rays from source are directed towards the detector in a thin band of radiation.
3. When gamma rays penetrate the thick wall of the tank, its energy level afterwards is greatly reduced.
4. The radiation received at the gamma detector is inversely proportional to the thickness of the walls and the medium between the radiation source and detector.
5. The amount of radiation received is inversely proportional to the amount of liquid between the radiation source and detector.
6. The difference in the amount radiation received by detector, corresponds to the liquid level in the tank.
7. Thus, when liquid level rises, the amount of radiation received is reduced and vice versa.