Honeywell SmartLine SLG 700 User Manual page 43

Interface accuracy and range
When measuring interface the accuracy of both the surface and interface level is ±3 mm and
the minimum interface thickness that can be measured is 7 cm. However, restrictions exist for
interface measurements depending on the application and on the dielectric constant (DC) of
the measured products:
- Maximum dielectric constant of the upper medium: 9
- Minimum dielectric constant of the lower medium: 10
- Minimum difference in dielectric constant between the upper and lower medium: 8
- Minimum upper product thickness: 7cm
In addition, the maximum upper product thickness that can be measured will be restricted by
the measured products. In the case of low absorption by the upper medium, upper product
thicknesses of greater than 30 meters can be measured. In contrast, in strongly absorbing
upper media, only upper product thicknesses of less than a couple of meters can be measured.
In general, absorption will tend to be higher in media with higher dielectric constant.
Therefore, the measurable thickness range of the upper product will be lower with higher
upper product dielectric constant applications (DC
When the upper product thickness drops below 15cm approximately, the surface and interface
reflections start to overlap. The transmitter will continue to measure the upper product
thickness accurately down to 7 cm although the echo curve might only show one reflection
for both surface and interface. If the transmitter fails to measure upper product thicknesses
below 15 cm or if the measurement of thin interfaces is inaccurate, it might be necessary to
adjust the reflection models using the Honeywell DTM. Refer to the SLG 700 HART Option
manual, #34-SL-25-06 for details on adjusting model parameters.
Note: The level transmitter is designed to measure properly only when the upper product
thickness is greater or equal to 7 cm. For example, upon restart the transmitter will not
attempt to provide a surface and interface measurement if the upper product thickness is less
than 7 cm.
Note: If the surface level is never going to exceed the minimum blocking distance high (min
BDH) for the transmitter configuration, it is recommended to keep full tank detection option
off.
Revision 8
SLG 700 SmartLine Level Transmitter User's Manual
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