Vessel Characteristics; Non-Contacting Radar Technology - Emerson Rosemount 3408 Reference Manual

Transmitter overview
September 2022
2.2.2 Foam and turbulence
Foaming liquids or turbulence may cause weak and varying surface echo amplitudes.
Surface turbulence is not normally a problem unless it is excessive.
Measurement in foamy applications depends largely on the foam properties. When the
foam is light and airy, the actual product level is measured. For heavy and dense foam, the
transmitter may measure the level of the foam's upper surface.
The Double Surface Handling function allows the user to select if the foam layer or product
surface should be used as output.
Related information
Process conditions
Double surface handling
2.3

Vessel characteristics

2.3.1 In-tank obstructions
The transmitter should be mounted so that objects such as heating coils, ladders, and
agitators are not in the radar signal path. These objects may cause false echoes resulting in
reduced measurement performance. However, the transmitter has built-in functions
designed to reduce the influence from disturbing objects where such objects cannot be
totally avoided.
Vertical and inclined structures cause minimal effect since the radar signal is scattered
rather than directed back to the antenna.
2.3.2 Tank shape
The shape of the tank bottom affects the measurement signal when the product surface is
close to the tank bottom. The transmitter has built-in functions which optimize
measurement performance for various bottom shapes.
2.4

Non-contacting radar technology

Non-contacting radar technology is ideal for a wide range of applications as it is
maintenance-free, has a top-down installation that reduces the risk of leakages, and is
unaffected by process conditions such as density, viscosity, temperature, pressure, and
pH.
The Rosemount 3408 uses Frequency Modulated Continuous Wave (FMCW) technology
and smart algorithms to maximize measurement accuracy and reliability, even in small
tanks and challenging fast-filling vessels.
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Reference Manual
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