While selecting an optimum type of level sensor for a particular application, one must resolve following issues:
- Which substance need to be measured, for example, liquid, slurry, solid, interface, granular, or powder.
- Specify whether the level sensor can be inserted into the tank or kept outside.
- Decide upon the suitability of continuous level or point sensor for the given application.
- Specify whether the substance being measured is electrically conductive or not.
- State the type of output required i.e. analog, relay or digital display.
- Indicate the required temperature and pressure ranges depending upon the application.
- Specify the required level measurement range.
- Identify whether turbulence, foam or vapor arises at the surface of the liquid or not.
- Make out whether material under consideration coats or builds up on surfaces.
In short, various physical and application variables which may affect the selection criteria of liquid level measurement sensors consist of:
- Phase of the substance under measurement i.e. liquid, solid or slurry
- Pressure or Vacuum
- Dielectric constant of medium
- Density or Specific gravity of medium
- Noise either acoustical or electrical
- Mechanical shock
- Tank or bin size and shape
- Response rate
- Ease of calibration or programming
- Physical size and installation of the instrument
- Monitoring or control of continuous or discrete i.e. point levels