Or 3-Point Calibration ('(Al 2-Pt, (Al 3-Pt') - Lovibond SD 310 Oxi Mode D'emploi

Air calibration for extremely precise measurements ('Cal Air')
The sensor is exposed to air at a rel. air humidity of 100 %.
Proceed as follows: Fill a bottle with some deionized water, close it and shake vigorously for
approx. 3 minutes to produce a water vapor saturation (100% rel. air humidity) in the air at
the top of the bottle. The temperature of the water and the ambient air should be the same.
Open the bottle and insert the sensor so that the membrane is in the air at the top of the bottle.
Caution! Do not immerse the membrane into the water or allow it to get wet. The bottle
opening should not be much larger than the sensor diameter. No excess pressure should
form in the bottle!
Note: A correctly calibrated sensor displays a measurement value of approx. 102 % O sat
2
in air and at room temperature.
Calibration is air-saturated water ('Cal AqUA')
This type of calibration is more difficult than the one described above and can easily produce
calibration errors if the appropriate care is not taken as the water can become easily over
saturated. To produce air-saturated water, pure water (25-30 °C) is poured from one container
into a second at a height of 50 cm and back again approximately 20 times. To prevent over-
saturation, wait approximately 5 min. and then calibrate the sensor (do not forget to stir!).
Start of the calibration: -Press and hold the button for 2 seconds.
'A,R appears in the display and as soon as the measurement values for oxygen and
temperature are constant, the calibration is automatically complete.
The sensor status resulting from the successful calibration is briefly displayed (evaluation in
10 % increments) (display briefly changes to xx % ELE[).
9.2

2 or 3-point calibration ('(AL 2-PT, (AL 3-PT')

The sensor is automatically calibrated to the atmospheric O2 concentration of air (20.95%)
and one or two additional concentrations. Calibration can be performed either on gases ([AL
A,R: air, pure oxygen and/or pure nitrogen) or in the conditioned liquid ([AL AQUA). The liquids
must be exposed to the relevant gases for the relevant amount of time.
A common zero reference (0 % oxygen) for both types of calibration is sodium sulfite solution
(also can be used with [AL A,R)
1. Start of the calibration: -Press and hold the button for 2 seconds.
2. Calibration point 1: (Pt.1)
0% (ZERO) must be entered with the 3-point calibration,
100 or 0% with the 2-point calibration.
appears in the display as well as the reference you require:
- ZERO for 0% oxygen
- 0.2 for pure oxygen or oxygen-saturated water
As long as the display is flashing, no valid reference has been detected.
As soon as the measurement values for oxygen and temperature are constant, the calibration
of the first point is completed automatically.
The device will prompt you to enter the next reference to be entered (possible references
flashing)
3. Calibration point 2: (Pt.2)
appears in the display as well as the reference you want to enter.
- A,R for ambient air or AQUA for air-saturated water
- 0.2 for pure oxygen or oxygen-saturated water
- ZERO for 0% oxygen
46 SD_310_2 07/2018