19
A
dvanced
S
ensor
T
echnologies,
I
nc. U.S.A.
Website:
www.astisensor.com
IOTRON
TM
Trademark of ASTI
IOTRON
TM
pH / ORP / ISE / DO / Conductivity Measurement Products Lines
“Auto Calibrate D.O. Sensor” Menu – Dissolved Oxygen PPM readings
The current dissolved oxygen ppm readings, computed
percent saturation values and temperature readings are
shown for selected channel in this screen along with the
existing currently slope calibration value as well as the
time since this calibration was last performed.
The smart digital HiQDT MODBSU RTU dissolved
oxygen sensors automatically compute the current
dissolved oxygen ppm value for the current dry in air
conditions using the temperature and ambient air
pressure as the basis.
Click on the “Calibrate” button to start the fully
automated calibration procedure. If calibration is
successful then “Calibration Complete” is shown. After
dampener time expires the new calibration result will
be shown and the time since calibration will show as
0.00 days. The exact value of pH buffer at cal temp
shown as “Calibrated Value”.
NOTE 1: The percent saturation value shown on this
calibration screen (register 30006 from the HiQDT D.O.
sensor) may differ from the percent saturation value that is
shown on the main display. The percent (%) saturation
value that is computed and shown in the calibration screen
excludes the salinity correction since this is not appropriate
during the dry in air calibration process of the sensor. The
percent (%) saturation that is computed and displayed in the
main screen (as well as the basis for all analog & digital
outputs and relays) including the salinity correction. The
ambinet air pressure that is user entered is always used when
computing the precent (%) saturation value in all modes.
NOTE 2: Review “Appendix E & F” for details about
how percent (%) saturation is computed from measured
dissolved oxygen ppm and temperature values as well
as the user entered air pressure and salinity.
It is best practice to view the result of your calibrations
to ensure that everything is shown as expected. An
example is shown to the right for bringing up the
sensor calibration display screen for the channel which
was just calibrated in the screenshots showing the
calibration of the dissolved oxygen sensor.
The “D.O. sensor Set Up” allows for user entered
values for the salinity of the measured solution and the
ambient air pressure where at the installation site.