Instrumentation : Selection of level instrument

How to select level instrument for measurements .

Type of the content : Liquid / Solid / Slurry / Powder Continuous Level measurement / Discrete Level Measurement Operating temperature and pressure Range Accuracy of level measurement
Whether the measured medium is electrically conductive or not ? Can the sensor be in direct contact with the process fluid (Contact Type / Non Contact Type ) Is it possible to penetrate the level sensor to the vessel wall or inside it ? Condition of process fluid : Turbulence / Foam or Vapor at the surface Type of Output required : Digital Output - Eg :Level switch Analog Output - Eg: Radar transmitter Type of display Remote / Integral