ATI
Q46D-ODO Optical D.O. System
Part 6 - Calibration
51
O&M Manual
Rev-J (8/17)
7.
The system now begins acquiring data for the calibration value. As
data is gathered, the units for ppm and temperature may flash.
Flashing units indicate that this parameter is unstable.
8. The calibration data point acquisition will stop only when the data
remains stable for a pre-determined amount of time (approximately 15-
20 seconds.) This can be overridden by pressing ENTER. If the data
remains unstable for 10 minutes, the calibration will fail and the
message
Cal
Unstable
will be displayed.
9. If accepted, the screen will display the message
PASS
with the new
sensor slope reading, and then it will return to the main measurement
display. If the calibration fails, a message indicating the cause of the
failure will be displayed and the FAIL icon will be turned on.
10. The range of acceptable values for sensor slope is 20% to 500%. It
may be necessary to rebuild the sensor as described in section 5,
Dissolved Oxygen Sensor Assembly.
Should the slope value remain out of range and result in calibration
failures, review the Service Section of this manual, then contact the
Service Dept. at ATI for further assistance.
6.13 Dissolved Oxygen Zero Cal
Dissolved oxygen sensors have extremely low offset outputs at zero. For
this reason, it is normally sufficient to simply leave the zero at the factory
default of 0 mV unless longer cable lengths are added to the sensor. As
an alternative if non-standard cable lengths are added, a zero can be set
by sensor from the performing the steps below.
For total cable length of:
Off-set Zero
30 m (98 ft)
0.96 mV
50 m (164 ft)
1.39 mV
60 m (200 ft)
1.90 mV
These steps below assume that the sensor has been connected to the
monitor with the monitor powered for 2 hours. During this period, the
sensor should be wet.
1. Remove the sensor from the application if necessary. Clean and rinse
if required.
