Dynasonics DDFXD Doppler Ultrasonic Flow Meter - Manual (Page 49)

06-DPP-UM-00147 02/12 49
LINEARIZATION
LINEAR – ENTRY OF LINEARIZATION DATA
The Linearization feature allows for correction of flow readings caused by non-linear flow measurement.
This typically occurs when there is insufficient straight piping before or after the location where the
transducers are mounted.
Up to 10 linearization points may be entered. The microprocessor will perform a linear interpolation
between data points entered in the linearization table and apply the associated correction factor to the
measured flow rate.
Start by entering the number of linearization points to be entered at the NUM PTS prompt. If a value of
00 is entered, linearization is disabled.
The unit will then prompt for FREQ 1 to be entered. Enter the measured frequency corresponding to the
flow rate for the first point. This can be obtained by running actual flow with the DISPLAY mode set to
DIAG and reading the measured frequency, or by calculating the frequency if the flow rate in feet per
second is known using the following formulas:
DT9 Clamp-On Transducer:
Freq = Velocity (FPS) × 80 Hz
DP7 Insertion Probe Transducer:
Freq = Velocity (FPS) × 80 Hz
The unit will then prompt for COEFF 1 to be entered. This is the value that the measured flow rate will
be multiplied by at this point. Enter the coefficient or correction factor to be applied. The value entered
must be between 0.5 and 1.5.
Repeat this procedure for all of the linearization points. When all of the points have been entered, the
unit will return to the NUM PTS prompt. Press the Menu key to return to the main menu LINEAR prompt.
Then using the arrow keys, move to the next setup parameter.