Direct methods used for level measurement in a tank or storage vessel are
1.Based on direct visual observation on the indicators like
- Gauge stick
- Hook gauge
- Gauge glass
2.Based on the position of a detectable material
- Float Gauge
3.Buoyancy methods:
- Float Gauge
- displacer gauge
Indirect methods for measuring the liquid level in a storage containers
1.Utilizing the hydrostatic head developed by the liquid
- Pressure gauge
- Air- Trap
- Diaphragm box method
- Air or Gas purge method
- Differential Pressure method
2.By using radioactive radiation
3.Electrical properties like capacitance, conductance and resistivity can be use used for level measurement
4.By using the property of reflection of waves from the liquid surface.
The above class of methods used for measuring the level of fluids which are stored in a storage vessel and container in chemical industries, their even advanced method practiced for accuracy and precision. The methods discussed are easy and cheaper to use a service. In an evaporator, the liquid level should be maintained at a certain depth in the heat region so that the rate of heat transfer which it was designed will be achieved, if the case liquid level drop the coil which used for the heating purpose may fail out. Even controlling the pumping operation a level control system will help to start and stop the pumping of fluid into the storage tank. A simple level control can be made easily with minimum accessories.