Dynasonics D7700 Series Insertion Doppler Ultrasonic Flow Meter - Manual (Page 25)

Rev. 2/00
-4.2- 77X
FIELD CALIBRATION PROCEDURES
After the Equipment is properly installed and
operating, there may be a need to field calibrate the
flowmeter. This could be caused by a number of
reasons:
1. Using a size pipe other than the one specified
when factory configured.
2. When used to measure a liquid with a sound
speed that is different than the one specified when
factory configured.
3. When proper lengths of straight pipe are not
available.
4. Percent of solids are greater than 2%.
5. Operating off turbulence or non-linear suspended
solids.
Field Calibration is as follows:
A. To calibrate the flow rate indicators (meter)
against a known flow:
1. With an established flow, the digital readout and/
or current outputs on D7700 can be adjusted in
accordance with a verified flow measurement, by
adjusting pot R30 (SPAN) adjustment. Turning
the pot C.C.W. decreases the reading. This is a
20 turn, stop-less potentiometer. (Note: Pot R60
will adjust the 0-1 mA output only).
2. It is desired to adjust 4-20 mA to other than
factory calibration, pot R50 can be used to adjust
the 20 mA span.
3. Adjust damping pot R110 for desired flow
response. CW rotation increases flow damping.
The total flow damping range can be varied from
about 5 seconds to 50 seconds. This setting is
usually used to smooth out chart recorder
readings.
PART 4 - CONFIGURATION AND OPERATION
Field Calibration
Procedure