Operation Function
1 or 2-point
calibrations
• The default calibration point is set to one at 100% saturation.
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• Use the arrow keys to set the calibration point to 1 or 2.
• After this data is kept or cancelled, the display shows the current number of calibration
points.
Calibration method
• Use the arrow keys to set the first calibration standard.
• If the meter is setup for two DO points, do these steps again for the second calibration
point.
Note: If the DO calibration units are changed in setup, (e.g., from % to ppm), the meter automatically
changes the values entered in this step to the selected units. Since the conversions are approximate,
enter the necessary values in this procedure (for maximum accuracy) in the correct calibration units.
Note: DO calibrations are not salinity compensated. The salinity value from an attached salinity probe or
the salinity value entered in setup will be ignored.
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This assumes a nominal slope of 47 mV from 0% to 100% at 25 ºC at 1013 hPa barometric pressure with
0 ppm salinity.
4. Push ENTER to keep the changes and go back to setup mode.
Note: To exit and not keep the changes, push CANCEL.
Set the Barometric pressure compensation units
DO measurements are sensitive to barometric pressure. The meter has a built-in barometer to give
automatic compensation of barometric pressure.
The meter shows barometric pressure in Hg (inches of mercury), mmHg (millimeters of mercury), or
hPa (hectopascals or millibars). The default unit is set to hPa.
1. Set the power to on.
2. Push SETUP, then DO to put the meter in the DO setup mode.
3. Use the arrow keys until "bAr Unit" shows on the display.
4. Push ENTER, then use the arrow keys to set the barometric pressure units (hPa, mmHg and
inHg).
5. Push ENTER
to keep the changes and go back to setup mode.
Note: To exit and not keep the changes, push CANCEL.
6. Next, use the numeric keypad or the arrow keys to set the salinity compensation value.
7. Push ENTER to keep the changes and go back to setup mode.
Note: To exit and not keep the changes, push CANCEL.
Calibrate for DO measurement
Calibrate the H280G and H280GB benchtop meters to measure DO with two methods: the water-
saturated air method or the water sample with a known DO concentration method.
Up to two calibration points can be done at any concentration. If a 1-point calibration is done, the
meter replaces the calibration point in storage that is most near the new calibration point (e.g., a new
100% DO single-point calibration replaces the calibration point in storage that is closest to a 100%
DO value). Both methods can do 1-or-2-point calibrations. During setup, calibration and
measurement units can be set to % or mg/L.
N O T I C E
DO is related to barometric pressure. The meter has a built-in barometer that will do automatic compensation for
barometric pressure.
Note: Do not set the power to off and remove the probes during conductivity or DO modes because the meter will
show an error the next time the meter is set to power on. Exit conductivity or DO modes before shutdown.
Calibrate with a known concentration method
To measure DO, make sure that the concentration is already known.
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