Eutech DO 1730 Dissolved Oxygen Meter 25
Chapter 4
Calibration
4.1 DO Calibration
4.1.1 DO Calibration Overview
The Eutech DO 1730 dissolved oxygen meter measures
dissolved oxygen as percent saturation, dissolved oxygen
as concentration in mg/L and dissolved oxygen as
concentration in ppm.
When the dissolved oxygen as percent saturation
calibration is performed, it will only be applied to dissolved
oxygen as percent saturation measurements. When
measuring dissolved oxygen as percent saturation, perform
a one point 100% water-saturated air calibration to
standardize the system. Optionally, a second point 0%
dissolved oxygen calibration can be performed to help
improve accurate low range dissolved oxygen readings.
When the dissolved oxygen as concentration calibration is
performed, it will only be applied to dissolved oxygen as
concentration measurements. When measuring dissolved
oxygen as concentration, perform a one point calibration
using a custom dissolved oxygen standard to standardize
the system.
The non-volatile meter memory retains the most recent,
active calibration data when powered off.
When the dissolved oxygen electrode is replaced, it is best
to clear the calibration log. Refer to the
for detailed instructions.
Note: Dissolved oxygen levels vary with temperature,
barometric pressure and salinity, so calibration must be
performed with consideration of these factors. It is
necessary to set the proper temperature, barometric
pressure and salinity values prior to performing any DO
calibration or measurement.
The default barometric pressure value is 760 mmHg (1.013
bar), which results in a theoretical calibration value of 100%
saturation in air. If the barometric pressure setting is
changed, the meter will automatically adjust to a new
percent saturation calibration value, corrected for the
adjusted barometric pressure. The following table provides
calibration values for two barometric pressure values. Note
that the percent saturation value (92.1%) decreases with a
lower barometric pressure value.
% Saturation
(of factory
default value)
Calibration Value
(760 mmHg)
Calibration Value
(700 mmHg)
Less than 10%
0%
0%
10.1% to 49.9%
Calibration Error
Calibration Error
50% to 150%
100%
92.1%
150.1% to 300%
Calibration Error
Calibration Error
4.1.2 DO Cal. Procedure for 100%
Saturation
Calibration of a DO electrode can be done quickly and
conveniently using the water-saturated-air method. Under
equilibrium conditions, the partial pressure of oxygen in air-
saturated-water is equal to the partial pressure of oxygen
in water-saturated-air (air at 100% relative humidity). So, an
electrode calibrated in water-saturated-air will correctly
read the partial pressure of oxygen in a water sample.
Note: Prepare a calibration chamber by placing the DO
electrode in an air-tight sealed bottle with about 50 mL of
water. The DO electrode must be suspended above the
water and not immersed in the water.
Ensure the active measure mode is dissolved
oxygen as percent saturation.
Press the “Cal” key to start the calibration.
Rinse the DO electrode and place into the prepared
calibration chamber.
Wait for the DO value to stabilize.
a.
While the reading is stabilizing, the stopwatch
icon is shown and the reading flashes.
b.
When the reading is stable, the checkmark icon
is shown, and the reading is solid.
Once the reading is stable, press the “Enter” key to
accept the DO value.
The meter will display the calculated slope value and
then proceed to the main measure mode.
Note: Press the “Measure” key at any time to abort the
calibration and return to the main measure mode.
Summary of Contents for Eutech DO 1730
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