Dynasonics TFX Ultra Transit Time Flow Meters - Manual (Page 52)

MIN RATE
SETTING
MAX RATE
SETTING
SUB FLOW
SETTING
DISPLAY READING
DURING ERRORS
0.0 1000.0 0.0 0.000
-500.0 500.0 50.0 0.000
-100.0 200.0 33.3 0.000
0.0 1000.0 -5.0* -50.00
Table 11: Sample Substitute Flow Readings
SET ZERO — Set Zero Flow Point (Choice)
NO
YES
Because every flow meter installation is slightly different and sound waves can travel in slightly different ways through these
various installations, it is important to remove the zero offset at zero flow to maintain the meter’s accuracy. A provision is
made using this entry to establish “Zero” flow and eliminate the offset.
Procedure:
1) The pipe must be full of liquid.
2) Flow must be absolute zero - securely close any valves and allow time for any settling to occur.
3) Press ENTER, use the arrow  keys to make the display read YES.
4) Press ENTER.
D-FLT 0 — Set Default Zero Point (Choice)
NO
YES
If the flow in a piping system cannot be shut off, allowing the SET ZERO procedure described above to be performed or if an
erroneous “zero” flow was captured - like can happen if SET ZERO is conducted with flowing fluid, then the factory default
zero should be utilized. To utilize the D-FLT 0 function, simply press ENTER, then press an arrow key to display YES on
the display and then press ENTER.
The default zero places an entry of zero (0) into the firmware instead of the actual zero offset entered by using the SET
ZERO procedure.
COR FTR — Correction Factor (Value)
0.500 - 1.500
This function can be used to make the flow meter agree with a different or reference flow meter by applying a correction
factor / multiplier to the readings and outputs. A factory calibrated system should be set to 1.000. The range of settings for
this entry is 0.500 to 1.500. The following examples describe two uses for the COR FTR entry:
1) The meter is indicating a flow rate that is 4% higher than another flow meter located in the same
pipe line. To make the flow meter indicate the same flow rate as the other meter, enter a COR FTR
of 0.960 to lower the readings by 4%.
2) An out-of-round pipe, carrying water, causes the flow meter to indicate a measured sound speed
that is 7.4% lower than the Table 4.5 value. This pipe condition will cause the flow meter to indi-
cate flow rates that are 7.4% lower than actual flow. To correct the flow readings, enter 1.074.
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Page 52 March 2014