One of the main advantages of Guided Wave Radar (GWR) over other level measurement technologies, and one that has increased its popularity in industrial process applications, is the fact that it is immune to a variety of process conditions. Specific gravity changes, dielectric constant changes, temperature, pressure and vapor space changes all have virtually no effect on the performance of GWR transmitters.
However, one application in which a process variation does affect the performance of GWR can be found in the Power industry, where the need for accurate level measurement of boilers, feedwater heaters and deaerators is important. These applications, all containing saturated steam in the vapor space, require special attention.
Measurement error can be introduced into a saturated steam system due to speed of propagation variations in the GWR signal relating to vapor space dielectric. However, the error is predictable with the high frequency, electromagnetic pulses travelling down the probe at very near the speed of light.