Emerson Rosemount Analytical RDO, Manual

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5. Allow at least 5 minutes for the temperature to stabi-
lize before starting the calibration. Keeping the sen-
sor in the shade will help reduce drift caused by the
sun’s heat. Do not leave the sensor the calibration
chamber for more than 30 minutes, lest condensa-
tion form on the surface of the foil, leading to false
low readings after calibration. If condensation does
occur, remove the probe and dry the foil. Return the
sensor to the calibration chamber and continue.
6. Once readings are stable, start the calibration.
Select Menu, then Calibrate, then RDO PRO, then
Saturation, then One-point cal. The calibration
begins immediately.
7. The Calibration Beginning screen shown in Figure
6-3 appears. Note the Calibration Beginning icon
next to the mg/L reading. As the reading stabilizes,
the bar in the icon shrinks. When the word Nominal
appears, the stabilization is almost complete, and
the calibration can be accepted at this point by
selecting Nominal. However, for best results, wait
until Stable appears. Select Stable to accept the cal-
ibration. To end and return to the previous calibra-
tion, select Cancel.
6.3 TWO-POINT CALIBRATION (100% AND
0% SATURATION)
1. Set up the calibration chamber and probe as
described in Section 6.1.2 steps 1 through 5. The
100% saturation step must be done first.
2. Once readings are stable, start the calibration.
Select Menu, then Calibrate, then RDO PRO, then
Saturation, then Two-point cal. The calibration
begins immediately.
3. The Calibration Beginning screen shown in Figure
6-3 will appear and the other two screens will ap-
pear as the reading stabilizes. Wait until the word
Stable appears. Select Stable to accept the calibra-
tion and proceed to the 0% saturation step. To end
and return to the previous calibration, select Cancel.
MODEL RDO CALIBRATION
4. The 0% saturation step starts automatically.
Remove the probe and fill the calibration chamber to
the upper fill line with approximately 60 mL of fresh
sodium sulfite solution (see Figure 6-4). A teaspoon-
ful of sodium sulfite in a cup of water is adequate.
5. Place the probe in the sodium sulfite solution. Be
sure the thermistor thermowell (the small metallic
disc about 1/8 inch (3 mm) above the nose cone) is
completely submerged. Leave at least 1/2 inch
(12 mm) between the surface of the foil and the bot-
tom of the chamber. Do not allow the sensing foil to
rest on the bottom of the calibration chamber. Allow
at least 5 minutes for readings to stabilize.
6. The Calibration Beginning screen shown in Figure
6-5 appears. Note the Calibration Beginning icon
next to the mg/L reading. As the reading stabilizes,
the bar in the icon shrinks. When the word Nominal
appears, the stabilization is almost complete, and
the calibration can be accepted at this point by
selecting Nominal. However, for best results, wait
until Stable appears. Select Stable to accept the cal-
ibration. To end and return to the previous calibra-
tion, select Cancel.
Figure 6-3. The Figure shows the screens that
appear as the calibration progresses.
Figure 6-4. Fill the calibration chamber to the
upper line with fresh sodium sulfite solution.
Cancel
0% Saturation
0.04 mg/L
23.1°C
Stable Cancel
0% Saturation
0.02 mg/L
23.1°C
Nominal Cancel
0% Saturation
0.02 mg/L
23.1°C
Figure 6-5. The Figure shows the screens that
appear as the calibration progresses.