ATI
Q45D-ODO Optical D.O. System
Part 6 –Calibration
O & M Manual
Revision C (7/09)
49 -
6.12 Dissolved Oxygen Air Span Cal (% sat)
This is the recommended method for air temperatures greater than about
10C; however, it requires that the sensor be removed from the process
and cleaned. Once cleaned, the sensor is held in air and allowed time to
adjust to the air temperature. As the sensor temperature equilibrates, the
transmitter automatically calculates the new 100% saturation point utilizing
the temperature readings and the barometric pressure user data located
on page 64. This method therefore requires no user input during
calibration.
Note: It is very important to allow enough time for the
sensor to completely temperature equilibrate with the surrounding
air.
This method requires that the sensor be removed from the process,
cleaned, and Covered, shielding the sensor from direct sunlight. The
sensor membrane must be dry for this procedure, and not submerged in
liquid. This method requires no user input during calibration; however, if
this is the first time the system is being installed and calibrated, make sure
to enter the proper atmospheric pressure data and process conductivity
data prior to calibration.
1.
Remove the sensor from the process. Clean and rinse if necessary
with water, paying particular attention to cleaning the membrane.
2. Cover the sensor, if necessary, to shield it from the direct rays of the
sun. Remember, the membrane must not be submerged - it must be in
the air letting the sensor hang, membrane downward, while powered.
3.
Allow the system to operate undisturbed for at least 20 minutes. If the
system is stable, the value on the display will increase to some PPM
value and remain at that level. At that point, calibration can continue.
4.
Scroll to the CAL menu section using the MENU key and press ENTER
or the UP arrow key.
Cal D.O.
will then be displayed.
5. Press the ENTER key. The screen will display a flashing
1-spl
for 1-
point, a
%-sat
for Saturation air calibration, or a
3-zer
for zero
calibration. Using the UP arrow key, set for a
3-sat
span calibration
and press ENTER.
6. The display will prompt the user to hold the sensor in air and press
ENTER. If the sensor has already been removed from the process
and reached temperature equilibrium, press the ENTER key.
