Low Flow Cut-Off; Empty Tube Monitoring - Siemens SITRANS F Operating Instructions Manual

Functions

8.3 Low flow cut-off

8.3 Low flow cut-off
In certain applications, as for instance dosing applications, 0% flow signals below a certain
flowrate are desired. In these applications, the flow signal can be forced to zero, when the
flow is lower than a predefined flow value (Low Flow Cut-Off).
SITRANS FC430 provides two parameters for setting the low flow cut-off:
● Low Mass Flow Cut-Off
● Low Volume Flow Cut-Off
The low flow cut-off parameters influence all outputs of the device, for example Local User
Interface, Channel 1 to 4, and HART.
Depending on the process values selection of the output either Low Mass Flow Cut-Off or
Low Volume Flow Cut-Off will influence the output.
8.4

Empty tube monitoring

The empty tube monitoring function uses the process density for detecting an empty tube.
Use of this function is recommended for all standard applications.
NOTICE
Gas applications
Deactivate the empty tube monitoring function
Empty tube monitoring parameters
Two parameters for setting the empty tube monitoring function are available:
● Empty Tube Detection
● Empty Tube Limit
The empty tube monitoring is activated via the Empty Tube Detection parameter. When the
empty tube monitoring function is on, the massflow / volumeflow value is forced to zero if the
tube is empty.
The tube is defined as empty, if the measured density value is lower than the value defined
via the Empty Tube Limit parameter.
NOTICE
Process media density
Risk of unintentionally forcing flow values to zero, if the difference between the empty tube
limit density value and the density of the process media is not sufficient.
 Ensure sufficient difference between the empty tube limit density value and the process
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media density
SITRANS FC430 with HART
Operating Instructions, 03/2012, A5E03361511-01