Setting the Cell Constant
Before making any measurement, the cell constant must be entered.
The constant may be entered in units ofi'cm or /m
•
Connect the cell and power up by pressing the black switch
on the back
•
The instrument will automatically start up in conductivity
mode
Entering a Known Cell Constant
0
Press K. Units are shown in the top right comer of the dis
play. To change the units press K again.
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Using the .(J.1} keys, scroll up or down until the correct val
ue is reached. The cell constant is now set. Return to the
function you required by using the mode key.
Often the exact cell constant is unknown. A nominal value of, say,
1.00/cm is quoted and the cell and instrument must be calibrated
against a standard solution to obtain the exact value.
Determining an Unknown Cell Constant
0
©
0
e
Use a standard solution. E.g. 0.0IM KC! has a conductivity
of 1413µS/cm @2s
c
c
Press the MODE key to display conductivity
Place the cell in the standard. When the reading is stable,
use the fr.(). keys to adjust the displayed value to that of the
standard. (The CAL flag will flash).
Press K. The cell constant is now set and displayed. Return
to the function you require by pressing the mode key.
NOTE: DO NOT PRESS THE Enter KEY WHEN SETTING THE
CELL CONSTANT
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Setting the Temperature Coefficient
The conductivity of electrolytes changes with temperature. The rate
of this change is termed the temperature coefficient and differs for
all electrolytes. For most applications where the temperature is
unlikely to fluctuate, the default value of2%/
c
c is acceptable. This
applies to most weak solutions in the range 10 to 13,000µS/cm. If
more accurate temperature compensation is required, then the exact
temperature coefficient for the sample should be determined.
Determining an Unknown Temperature Coefficient
0
©
0
e
0
@
Place the cell in the sample.
Press %1
°
C key, then press Enter. (the %/
c
c will flash).
Change the temperature of the sample by 10 degrees.
Select %/
c
c. Press Enter. The new Coefficient is now dis
played. Make a note of this value.
Press the Mode key to display conductivity mode, then clear
the data by pressing the Clear key for 5 seconds.
Recalibrate to a known value and enter the calculated coef
ficient. (see below).
To Enter a Known Temperature Coefficient
If the temperature coefficient value is already known or has been
determined as above it may be entered as follows:
0
Select the %/
c
c key and clear any previous calibration data.
(Press Clear for 5 seconds)
©
Adjust the displayed value to the correct value using the .(J.
fr keys
0
The temperature coefficient has now been set. Select meas
urement mode.
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