Orion Lab Star EC112 Conductivity Meter 31
Condition the sample solution and conductivity
electrode to a temperature (T
2
) that is about 5 ºC to
10 ºC different from T
1
, and record the conductivity
reading C
T2
.
Note: Record your results for future reference. Ideally T
1
and T
2
should bracket your measurement temperature and
should not differ by more than 5 ºC.
Calculate the temperature coefficient of your
solution according to the formula shown above.
Enter the calculated temperature coefficient into the
meter.
The calculated temperature coefficient will now be applied
to all the meter readings.
5.4 Salinity Modes
When measuring salinity, select from one of the two
available salinity measurement modes: natural sea water
and practical salinity.
Practical salinity measurements are based on relating the
sample measurement to the reading of a standard
potassium chloride (KCl) solution at 15 °C. The meter will
automatically temperature compensate and report the
expected practical salinity result as practical salinity units
(PSU) at 15 °C when using a conductivity sensor with built-
in ATC sensor.
Natural sea water measurements use a historic convention
known as UNESCO 1966 and the meter will report the
expected natural sea water result as parts per thousand
(ppt).
5.5 Calculating TDS Factor
To determine the conductivity-to-TDS conversion factor,
the following formula can be used:
Factor = Actual TDS ÷ Actual Conductivity @ 25ºC
•
Actual TDS: Value from the solution bottle label or
as a standard made using high purity water and
precisely weighed salts.
ppm = milligram of salt per liter of water = mg/L
ppt = gram of salt(s) per liter of water = g/L
•
Actual Conductivity: Value measured using a
properly calibrated Conductivity/Temperature meter.
Both the Actual TDS and the Actual Conductivity values
must be in the same magnitude of units. For example, if
the TDS value is in ppm the conductivity value must be in
µS/cm; if the TDS value is in ppt the conductivity value
must be in mS/cm.
Check the factor by multiplying the conductivity reading by
the factor in the above formula. The result should be in
TDS value.
When the TDS factor is set to 1.0, Conductivity = TDS.
5.6 Data Viewing
Store up to 500 data points in the meter memory. Use the
item in the meter Setup Menu to view the data
log points, active conductivity calibration log, active TDS
calibration log, active salinity calibration log and active
temperature calibration log.
The data log shows the most recent data log point first.
The meter will save up to 500 data log points and then
automatically overwrite the oldest data log point with the
newest data log point when the limit is reached. Each data
log point is saved with its associated date and time stamp.
To view the time stamp with seconds included, the data
log must be exported to a computer or printer.
The conductivity calibration log and TDS calibration log
shows each calibration point and the calculated calibration
factor value. Two, three, four and five point calibrations will
display the average calibration factor value and then the
appropriate number of individual calibration factor values.
The salinity calibration log shows the calibration point and
the calculated calibration factor value. The temperature
calibration log shows the temperature and offset value.
Each calibration log is saved with its associated date and
time stamp. To view the time stamp with seconds
included, the calibration log must be exported to a
computer or printer.
Note: If desired, when in the View Logs item in the meter
Setup Menu, press the “Log/Export” key to export the
individual data log point or calibration log being viewed.
Summary of Contents for Orion Lab Star EC112
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