Process Condition Considerations; Turbulence; Foam Or Emulsions; Fep Probe - Honeywell SmartLine SLG 700 User Manual

2.6 Process Condition Considerations

Process conditions can affect the way the surface appears to the GWR Transmitter.

Turbulence

Turbulence can result in the following measurement issues:

The height of the surface reflection appears smaller.

The level measurements display higher variability.
In extreme cases of turbulence, the surface level measurement can be lost entirely. To conteract these
effects, it is a good idea to enable amplitude tracking, and to increase the maximum fill rate
parameter. Alternatively, instead of a single liquid application type, if the dielectric constant is low
enough, measurements can be made with the Low DC application type.

Foam or Emulsions

Foam on the surface of the material being measured can influence the measurement. While light
foaming would have no influence at all, very heavy foam can degrade the measuring signal. Foam can
result in:

The height of the surface reflection appearing smaller or even disappearing.

Loss of accuracy due to an badly-defined surface.
Also in this case, amplitude tracking (See Section 2.3.1). or a Low DC application (see section 2.5.3).
selection can be attempted to counteract these problems.

FEP Probe

Revision R200 introduced FEP-coated probes for SLG720 transmitters (Standard Temperature
and Pressure). FEP is very similar in composition to PTFE. It has most of the excellent physical,
chemical, and electrical properties of PTFE, but with the ability to be processed using
conventional thermoplastics processing techniques. With FEP-coated probes, the only wetted
material is FEP. In addition to avoiding chemical compatibility issues between the process
connector or probe with the chemical process being monitored, FEP-coated probes may avoid
some potential build up issues, either because process chemicals are less likely to stick to FEP or
because there are no voids in which chemicals can accumulate.
The application types available are single liquid, two liquid with interface measurement, and the
low-DC algorithm type. Internally the sensor has algorithms to correct for the dispersion (change
in pulse shape) of RADAR pulses along such probes. Typically these effects are only visible for
probe lengths over about 10 m (33 ft.). It is important that the user correctly selects FEP-coated
probes (either rod or wire) when setting up the sensor. FEP applications are a pay-for-feature
option. Refer to the HART or FOUNDATION Fieldbus User's Manuals for further details of
advanced configuration with these probes.
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SLG 700 SmartLine Level Transmitter User's Manual
Revision 8