Operational Guide
36
6. Press
CFM
. The message “MANUAL CALIBRATION CLEARS PREVIOUS
CALIBRATIONS” will be displayed on the third line LCD. “CAL” and “CFM
”
tags
will blink. Press
CFM
to confirm the manual calibration.
Note
: GLP will display “Manual” for a standard. Using this calibration technique
will erase any previous calibrations done in CAL. Log files will indicate “MANUAL”
as standard.
User Selectable EC/TDS Range (Not Available In Basic Mode)
The EC and TDS measurements may be configured in SETUP as AUTO (meaning
auto ranging, the measurement automatically finds the correct conductivity
or TDS unit and resolution), or it may be configured with a user-selected
measurement range and resolution (if you know ahead of time where your
samples will fall). If AUTO is selected, the meter will select the scale with
the highest possible resolution, but may change in the middle of a series of
measurements changing units and displayed resolution.
Note
: The selected range is only active during measurements. Auto ranging is
used during calibration. If a fixed range is selected and during measurement
goes beyond the range limits, the full scale value of that range will flash on the
display. All log data in the CSV files will be displayed in uS/cm.
General Guidelines
Calibrate the instrument frequently, especially if high accuracy is required.
The instrument should be recalibrated:
•
Whenever the EC probe is replaced.
•
At least once a week.
•
After testing aggressive chemicals.
•
If “CAL DUE” is displayed on the third LCD line.
Every time you calibrate the instrument use fresh standard and perform
electrode maintenance as required. It is recommended to choose a calibration
standard that is close to the sample.
Preparation
Pour small quantities of the standard solutions into a beaker. If possible, use a
plastic beaker to minimize any EMC interferences. For accurate calibration and to
minimize cross-contamination, use two beakers for the standard solution; one
for rinsing the probe and one for calibration.
Procedure
Select standard to be used for calibration. 0.00 μS (probe in air) may be used for
an offset calibration. This should be done first. Hanna Conductivity standards
are available at 84 μS/cm, 1413 μS/cm, 5.00 mS/cm, 12.88 mS/cm, 80.0 mS/cm,
111.8 mS/cm and are used for the cell factor calibration.
Rinse the probe with calibration solution or deionized water. Shake off excess
solution. Submerse the probe in the calibration solution. The sleeve holes must
be completely submersed. If possible, center the probe in the beaker away from
the bottom or beaker walls.
Raise and lower the probe to refill the center cavity and tap the probe repeatedly
to remove any air bubbles that may be trapped inside the sleeve.
EC Meter
Configuration
EC/TDS
Calibration
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