11 Calibration
Standard Calibration
Preparation
• Remove probe from process.
• Flush probe and cap with a jet of clean water.
• Inspect for scratches or voids in cap surface.
• Replace cap as required.
• Shake any remaining solution off the probe. No droplets should remain on the DO sensing surface before
performing the calibration procedure.
• Verify the controller’s barometric pressure reading with a reference meter. Pressure value can be adjusted
from the controller’s Technical Menu.
• Verify the temperature is reading correctly. The temperature value can be adjusted from the controller’s
Probe Setting menu.
• Set Salinity value if exposing the probe to ocean or brackish waters.
Procedure
• Set the controller to desired measurement unit.
Go to Probe Setting in Channel Setup and set required measurement mode (Meas.Mode): DO_Sat
(% saturation) or DO_Conc (Concentration).
• Press the
m
key then
CAL
virtual key. The controller recognizes the currently selected measuring unit.
Calibration at 100 % and 0 % saturation
To calibrate at 100 % saturation (or 8.26 mg/L) suspend the probe in water-saturated air. This condition
corresponds to 100 % air-saturated water at the temperature of measurement.
1. Use of calibration beaker containing some water or moistened absorbent material is recommended.
Loosely screw the beaker onto the probe (first thread only).
2. Allow 15 minutes for the air inside the beaker to become water saturated.
3. Press
CAL
to enter calibration mode after this 15 minute interval has elapsed.
The reading, temperature, atmospheric pressure (mmHg), calibration point and “Wait” message are displayed.
4. Once the reading has stabilized the
CFM
virtual key is displayed.
Press
CFM
to accept the calibration point.
“Wait” followed by “Calibration point is accepted and saved” are displayed.
Exit
and
Next
virtual keys are available. Pressing
Exit
saves a single point calibration.
5. Press
Next
to follow with second-point calibration.
6. To calibrate at 0 % (or 0 mg/L), place the probe in the
HI7040
zero oxygen solution and stir gently for
2-3 minutes. Dislodge bubbles that may adhere to the cap.
“Wait” message and stability indicator (blinking) are displayed.
7. Press
CFM
to accept the calibration point.
“Calibration point is accepted and saved” message followed by “Calibration DONE” are displayed.
Summary of Contents for HI7640-58
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