Hydrostatic level transmitters
a Sensor measures weight of the water column above it
Since weight of this column is propotional with the height of the liquid ,a sensor is used to ransform height into 4-20 mA signal .
This signal is controlled and viewed using controller device.
The cotroller analyses the 4-20 mAsignal to m ,mm, cm . It could be programmed to produce 3 relays as an output which can be adjusted to control various levels so this system can be used in tanks filling valves,operate pumps ,alarms for higher and lower level .