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DOTX-45 Dissolved Oxygen System Part 7 –Calibration

DOTX-45 47 -

4. Press the ENTER key. The screen will display a flashing 1-spl for 1-point, a

%-sat for Saturation calibration, or a 3-zer for zero calibration. Using the UP

arrow key, set for a 1-spl calibration and press ENTER.

5. 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. The calibration data point acquisition

will stop only when the data remains stable for a pre-determined amount of

time. This can be overridden by pressing ENTER.

6. If the data remains unstable for 10 minutes, the calibration will fail and the

message Cal Unstable will be displayed.

7. The screen will display the last measured ppm value and a message will be

displayed prompting the user for the lab value. The user must then modify the

screen value with the arrow keys and press ENTER. The system then

performs the proper checks.

8. If accepted, the screen will display the message PASS with the new slope

reading, 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.

7.13 Dissolved Oxygen Air Span Cal (% sat)

This is the recommended method for air temperatures greater than about 10°C;

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.

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Dot-x SERIES Specifiche Pagina 48