Operating Principle of Non-Contacting Radar Level Sensor/Gauges (Unguided Wave)---Part three

Accuracy Level of Radar Instruments

The achievable accuracy of any radar level measurement system depends heavily on the type of application, the antenna design, mechanical installation, the state and quality of the electronics and echo processing softwave employed. Even though the effects of temperature and pressure variations are very small, compensation methods are still being used for these parameters. Other influences on accuracy of radar level instrument include to noise radio and interference.

Areas of Application

Radar level instruments are widely used to measure the level of liquid, slurries as well as many solids in storage tank refineries and tank terminal. These instruments operate in a wide range of temperature, pressure, vapor das mixtures and various process conditions.

Application Limitations

Solid

Radar level instruments are quite specific in their application of use. Radar level instrument should be avoided as much of possible on the solids due to the weak signal reflection that occurs.

Low Dielectric Process Fluids

Non-contact radar sensors perform poorly with low dielectric process fluids. With low dielectric process fluid, much of the radiated energy is lost to the fluid, leaving very little energy to be reflected back to the gauge. Water and most chemical solution have a high dielectric constant; fuel oil, lube oil and some solids, such as lime, have a low dielectric constant. Their application is not suitable for these kinds of low dielectric fluids.

Surface Turbulence

If the surface is turbulent, whether from agitation, product blending, or splashing, more of the signal is lost. A combination of a low dielectric fluid and turbulence can limit the return signal to a non-contact radar sensor. To solve the problem of turbulence, bypass pipes or stilling wells can be used to isolate the surface from the turbulence.

Advantages

Used on difficult 'hard-to-handle' applications

High accuracy

Non-contact

Can measure level through plastic tanks

Used to monitor contents of boxes or other multi-media material

Detect obstructions in chutes or presses

Disadvantages

Very sensitive to build-up on sensor surface

They are very expensive. Price increases with increasing accuracy.