Hach sension6, Instruction Manual, Page: 42 / 86

41
SECTION 3,
continued
High concentrations of dissolved substances can be corrected for
by entering a sample Salinity value. However, Salinity values
may not produce an adjustment equivalent to the value obtained
by a Winkler titration because various ions affect the dissolved
oxygen concentration differently.
The sample used for this calibration should be similar in
temperature and atmospheric exposure to the sample used for the
determination made by an alternate method.
To calibrate the meter against a dissolved oxygen concentration
determined by an alternate method:
1. Place the electrode in the sample deep enough to fully cover
the thermistor (metallic button) located on the side of
the probe.
2. The sample must have a flow rate or stirring rate that allows
for accurate probe performance. See
Section 3.4.2 on
page 44 . Make sure that no air bubbles are trapped in the
sensing area of the probe tip.
3. Press the
CAL
key located in the lower left corner of the
keypad. The Cal icon will appear in the upper left corner of
the display, a flashing question mark will appear in the upper
right corner of the display, and the keypad icon will appear in
the lower left corner of the display. The main display will
show the current barometric pressure.
4. Press the
READ ENTER
key three times to skip to the display
showing
100%
.
5. Use the keypad to enter the concentration of the sample in
mg/L. Press the
READ ENTER
key. The stabilizing icon will
appear while the meter completes the calibration. When the
calibration is complete, the meter will return to the
read mode.
6. Press the
EXIT
key during the calibration sequence to back the
display screen up one at a time, then leave the calibration
routine without completing a calibration.
This calibration can be performed in conjunction with sample
salinity measurements. The salinity value can then be adjusted as