Guided-Wave Radar Level Gauge (A+E 61L)Measurement Principles
Low power, nano-second microwave pulses are guided down a probe submerged in the process media. When a microwave pulse reaches a media with a different dielectric constant, part of the energy is reflected back to the transmitter. The transmitter uses the residual wave of the first reflection for measuring the interface level. Part of the wave, which was not reflected at the upper product surface, continues until it is reflected at the lower product surface. The speed of this wave depends fully on the dielectric constant of the upper product. The time difference between the transmitted and the reflected pulse is converted into a distance, and the total level or interface level is then calculated. The reflection intensity depends on the dielectric constant of the product. The higher the dielectric constant value, the stronger the reflection is.Features
Unlike older technologies, guided-wave radar (GWR) offers measurement readings that are independent of the chemical or physical properties of the process media with which it is in contact. Additionally, GWR performs equally well in liquids and solids.
GWR is suitable for a variety of level measurement applications including those that involve:
--Unstable process conditions—Changes in viscosity, density, or acidity do not affect accuracy.
--Agitated surfaces—Boiling surfaces, dust, foam, and vapor do not affect device performance. GWR also works with recirculating fluids, propeller mixers, and aeration tanks.
--High temperatures and pressures—GWR performs well in temperatures up to 220°C and can withstand pressures up to 60bar.
--Fine powders and sticky fluids—GWR works with vacuum tanks filled with used cooking oil as well as tanks holding paint, latex, animal fat, soybean oil, sawdust, carbon black, titanium tetrachloride, salt, and grain.
With the advantage of easy installation and low power consumption, the GWR level transmitter suits most liquid and solids level applications and liquid interface applications.