7
Reference Manual
00809-0100-4308, Rev BA
Section 2: Transmitter Overview
December 2014
Transmitter Overview
2.3.2
In-tank obstructions
The Rosemount 3308 Series Transmitter is relatively insensitive to objects in the tank since the
radar signal is transmitted along a probe.
Avoid physical contact between probes and agitators as well as applications with strong fluid
movement unless the probe is anchored. If the probe can move within 1 ft (30 cm) away from
any object, such as an agitator, during operation then probe tie-down is recommended.
In order to stabilize the probe for side forces, you have the option to either hang a weight at the
probe end (flexible probes only) or fix/guide the probe to the tank bottom.
2.3.3
Interface level measurement
Rosemount 3308 Series Transmitter is well suited for measuring the interface of oil and water, or
other liquids with significant dielectric differences.
Figure 2-5. Interface Level Measurement
All probes can be used for measuring interfaces. Single probes are the preferred choice in almost
all applications but depending on the application and installation geometries a coaxial probe or
a flexible twin probe may be a better fit.
For measuring the interface level, the transmitter uses the residual wave of the first reflection. 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 maximum allowable upper product thickness/measuring range is primarily determined by
the dielectric constants of the two liquids. Target applications include interfaces between
oil/oil-like and water/water-like liquids. For such applications the upper product dielectric
constant is low (<3) and the lower product dielectric constant is high (>20). Refer to
for further interface application guidelines.
Product Level
Interface Level
Interface Level
Summary of Contents for 3308A Rosemount 3308 Series
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