Figure 2-12: Two-Liquids Non-Flooded - Honeywell SmartLine SLG 700 User Manual

Two-liquid non-flooded application type is used in cases such as water beneath a
hydrocarbon in a separation tank. Both the top level and interface must be measured. The
low-DC material is assumed to be on top of the higher DC material. As of R200 this
application type is a pay-for-feature option; however, transmitters installed prior to R200 will
automatically generate a license for this application if the device is upgraded.
In two-liquid applications the dielectric of the upper liquid is required to measure the true
position of the interface between upper and lower fluid. Errors in this value result in error of
the interface and its thickness.
It is recommended that the Max Filling rate be set as low as is acceptable (say 0.1 m/s)
because it reduces the chance that the wrong echo is selected during the processing of the
RADAR echo. Amplitude tracking should be turned on, especially if the attenuation of the
upper fluid is not well known.
Note that if the primary variable is either interface position or thickness, the sensor stops
reporting as soon as the surface has entered the set blocking zone. Surface measurements are
not made in the blocking zone but are required to measure the true position of the interface. If
the level moving into blocking zones is unavoidable, the sensor should be set to Non-
Latching mode (HART transmitters), where once the primary variable is lost, a new full
probe scan is triggered until the transmitter recovers.
When measuring interface the accuracy of both the surface and interface level is ±3 mm or
0.03%, whichever is greater, 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.
Revision 8

Figure 2-12: Two-liquids non-flooded.

SLG 700 SmartLine Level Transmitter User's Manual
Page 29