dynasonics TFXL series - Page 35

Flow Tab
Figure 33: Flow tab
Parameter Meaning Option Description
Flow Rate
Units
Engineering units
for flow rate
Menu selection
Select an appropriate rate unit and time from the two lists. This entry also includes the selection
of Flow Rate Interval after the virgule ( / ) sign.
Totalizer Units
Engineering units
for totalizer
Menu selection
Select an appropriate totalizer unit and totalizer exponent. The totalizer exponents are in
scientific notation and permit the eight digit totalizer to accumulate very large values before the
totalizer “rolls over” and starts again at zero.
Min Flow
Minimum
volumetric flow
rate
(Enter a numeric
value)
Enter the minimum volumetric flow rate setting to establish filtering parameters. Volumetric
entries are in the flow rate units. For unidirectional measurements, set Min Flow to zero. For
bidirectional measurements, set Min Flow to the highest negative (reverse) flow rate expected in
the piping system.
Max Flow
Maximum
volumetric flow
rate
(Enter a numeric
value)
Enter the maximum volumetric flow rate setting to establish filtering parameters. Volumetric
entries are in the flow rate units. For unidirectional measurements, set Max Flow to the highest
(positive) flow rate expected in the piping system. For bidirectional measurements, set Max Flow
to the highest (positive) flow rate expected in the piping system.
Low Flow
Cutoff
Flow cutoff value
(Enter a numeric
value)
Allows very low flow rates (that can be present when pumps are off and valves are closed) to be
displayed as zero flow. Enter values between 1.0…5.0% of the flow range between Min Flow and
Max Flow.
Low Signal
Cutoff
Low signal cutoff
value
(Enter a numeric
value)
Drives the transmitter and its outputs to the value specified in the Substitute Flow field when
conditions occur that cause low signal strength. A signal strength indication below 5 is generally
inadequate for measuring flow reliably, so generally the minimum setting for low signal cutoff is
5. A good practice is to set the low signal cutoff at approximately 60…70% of actual measured
maximum signal strength. The factory default low signal cutoff is 5.
If the measured signal strength is lower than the low signal cutoff setting, a Signal Strength too
Low highlighted in red appears in the text area to the left in the Data Display screen until the
measured signal strength becomes greater than the cutoff value.
Signal strength indication below 2 is considered to be no signal at all. Verify that the pipe is full
of liquid, the pipe size and liquid parameters are entered correctly, and that the transducers
have been mounted accurately. Highly aerated liquids also cause low signal strength conditions.
Substitute
Flow
Substitute flow
value
0.0…100.0
A value that the analog outputs and the flow rate display to indicate when an error condition in
the transmitter occurs. The typical setting for this entry is a value that will make the instrument
display zero flow during an error condition.
Substitute flow is set as a percentage between MIN RATE and MAX RATE. In a unidirectional
system, this value is typically set to zero to indicate zero flow while in an error condition. In a
bidirectional system, the percentage can be set such that zero is displayed in a error condition.
To calculate where to set the substitute flow value in a bidirectional system, perform the
following calculation:
100
100 -
-
×
=
Maximum F low
S ubstitute F low
Maximum F low Minimum F low
Some typical settings to achieve zero with respect to MIN RATE and MAX RATE settings are
listed below.
OTE:N *The UltraLink software utility is required to set values outside of 0.0…100.0.
Conguration Menu
Page 35 April 2016 TTM-UM-00369-EN-03