Dynasonics D300_301 Series Doppler Ultrasonic Flow Meter - Manual (Page 25)

Rev. 2/00 -4.6- 300/301
HOW TO CALIBRATE FOR A DIFFERENT SCALE
& PIPE
This procedure is an outline of how to re-scale the
series D300/301 flow meter.
1. The first step is to determine the full scale velocity
setting. To determine this you would need the full
scale setting (i.e. GPM, MGD etc) and the pipe inside
diameter (refer to the charts in the Appendix).
Example calculation: Full scale 500 GPM. Pipe size:
4.026 inches I.D.
Feet per Second = 500 GPM = 12.755 FPS
(4.026)
2
x 2.45
2. Multiply the Full Scale in FPS by 120 Hertz.
12.755 * 120 = 1530 Hertz.
3. As described in the Electronic Calibration section
on page 4.4 of this operations manual, input a 1Vpp
sine-wave at 1530 Hz into TP3 to simulate full scale
flow.
4. Adjust R30 (SPAN) for 5.0 VDC at TP7. On A
D301 meter adjust the digital indicator located on the
door of the instrument. The adjustments for the
scaling on the digital indicator are also labeled SPAN.
The fine adjustment on the digital indicator is labeled
CAL. Use both of these adjustments to correctly set
the indicator.
5. On a D301 equipped with a totalizer the new count
rate would be determined by the following example:
60/500 = 0.12 sec per count. In this example it has
been determined that 1 count at .12 sec per count is
equal to 1 gallon. Since 0.12 seconds is too fast for
the electronic circuit design (i.e. 0.5 sec minimum
setting), the decimal place is moved over one and
PART 4 - CONFIGURATION AND OPERATION