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6.25 ROX Optical Dissolved Oxygen Calibration
ALWAYS ensure that the temperature sensor is completely submerged during all
calibrations. Failure to submerge the sensor can result in false calibrations. And, ALWAYS
allow time for the temperature of the standard and the sensor to equilibrate.
YSI recommends a 1-point calibration for the optical DO sensor. If you If you
suspect that the sensor has drifted, you may want to perform a 2-point calibration.
For instruction on 2-point calibration, contact YSI Technical Support or refer to the
YSI 6-Series Multiparameter Water Quality Sondes User Manual available online at
www.ysi.com.
When you calibrate the optical DO sensor for oxygen % saturation or oxygen mg/L, the sensor automatically calibrates
for the other value simultaneously (i.e. calibration for ODOsat% results in DOmg/L calibration and vice versa).
1-Point Dissolved Oxygen (% Air Saturation) Calibration
1. Rinse the sensor in water.
2. Leave approximately 1/8 inch of water in the bottom of the calibration cup. Also leave the cup vented to air
(you may want to keep the fluid input port open to allow for air exchange). The goal is to achieve a water-
saturated air environment.
3. Wait approximately 10 minutes to allow temperature and air pressure to equilibrate.
4. Open the ‘Calibrate’ menu.
5. Select ‘ODOsat%.’
6. Select ‘1-Point.’
7. The screen will prompt you to enter the current barometric pressure in mm of Hg. (mm of Hg = 25.4 x
inches of Hg).
8. NOTE: Use uncorrected (true) laboratory barometric readings only. Weather service readings are corrected
to sea level. To “uncorrect” weather service readings apply this formula:
9. True BP = [Corrected BP]-[2.5 x (Local altitude above seal level/100)]
10. Input the true barometric pressure and press ‘Enter.’
11. Observe the ODOsat% until the value exhibits no significant change for approximately 30 seconds.
12. Press ‘Enter’ to accept the calibration.
13. Drain the standard from the cal cup and rinse with water.
Calibrate Using mg/L 1-Point
YSI recommends that you do not calibrate the EcoMapper using this method. If you have calibrated a YSI sonde
previously using this method or have SOPs that require the instrument to be calibrated in this manner, please refer
to the YSI 6-Series Sonde Manual. If you have not performed this procedure before but you have a specific reason to
calibrate through this procedure, please contact YSI Technical Support. Remember, calibrating the sensor using ‘% Air
Saturation’ allows you to measure and record data in mg/L of DO even though it is not the selected calibration method.
NOTE
6.2