Process Characteristics; Coating; Bridging; Foam - Emerson Rosemount 3300 Series Reference Manual

Rosemount 3300 Series
PROCESS
CHARACTERISTICS

Coating

Bridging

Foam

Vapor

2-8
The Rosemount 3300 Series has a high sensitivity due to its advanced signal
processing and high signal to noise ratio, which makes it able to handle
various disturbances. However, the following circumstances should be
considered before mounting the transmitter.
Coating on the probe should be avoided since the sensitivity of the transmitter
may be decreased leading to measurement errors. In viscous or sticky
applications, periodic cleaning may be required.
For viscous or sticky applications, it is important to choose a suitable probe:
Coaxial
500 cP
Coating not recommended
(1) Consult factory if agitation/turbulence and high viscous products.
Maximum measurement error due to coating is 1-10 % depending on probe
type, dielectric constant, coating thickness and coating height above product
surface.
Heavy coating that results in product bridging across the two probes for twin
lead versions, or between the pipe and the inner rod for coaxial probes, will
cause erroneous level readings and must be prevented. Single lead probes
are preferred in this case.
How well the Rosemount 3300 Series Radar Transmitter measures in foamy
applications depends upon the properties of the foam; light and airy or dense
and heavy, high or low dielectrics, etc. If the foam is conductive and creamy
the transmitter will probably measure the surface of the foam. If the foam is
less conductive the microwaves will probably penetrate the foam and
measure the liquid surface.
In some applications, as ammonia, there is heavy vapor above the product
surface that will influence the level measurement. The Rosemount 3300
Series Radar Transmitter can be configured to compensate for the influence
of vapor.
00809-0100-4811, Rev AB
Twin Lead
Maximum viscosity
1500 cP
Coating/Build-up
Thin coating allowed, but no
bridging
Reference Manual
July 2003
Single Lead
(1)
8000 cP
Coating allowed