Guided Wave Radar
Measuring principle
High-frequency radar pulses are coupled onto a rod and gui
ded along the probe. The pulse is reflected by the
product surface. The instrument calculates the level from the running time of the radar pulses. A controller limits
the burner at a set low water level position. The analogue signal is also available for external controllers to make
decisions about controlling the water level or providing warnings.
Transmitter
Transmitted Pulse
Waveguide
Reflected Pulse
Tank Wall
Process Fluid
Signal
Out
Figure. 1 - Guide
d Wave Radar
Advantages
GWR sensors operate independently of noise, pressure or temperature fluctuations and are also completely
unaffected by changes i
n densi
ty, foaming or steam. Build-up on the probe or on the container wall does not affect
the measurement either. GWR probes detect the physical presence of the water rather than the conductivity of the
fluid. This allows the device to operate in boiler water with very low or varying conductivity such as RO or
De-mineralised water. No polarising electrical connection is made through the probe so scale build-up is
significantly reduced.
Integrity
The GWR unit that Fulton supplies is certified to provide SIL2 level of protection against low water level.
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