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6.2 Calculating the ATC Coefficient of a Solution
1. Set the ATC Coefficient to zero using the procedure detailed in section 6.1.
2. Ensure that the temperature function has been calibrated (see section 5.1).
The conductivity function does not need to be calibrated at this point.
3. Warm or cool the solution to approximately 5
O
C below the temperature at
which you expect to take sample measurements. Record the Conductivity and
Temperature readings once both have become stable.
4. Warm the solution to approximately 5
O
C above the temperature at which
you expect to take sample measurements. Record the Conductivity and
Temperature readings once both have become stable.
5. Apply the following formula, where C1 and T1 are the first readings taken,
and C2 and T2 are the second readings taken…
C2
Log C1
T2 - T1
ATC Slope = 100 x 10 - 1
6. Enter the result that is obtained as the ATC Coefficient of the solution, as per
the procedure detailed in section 6.1.
Note
To assist in calculating the ATC Slope, the following information can be entered
into a spreadsheet. This example has been specifically written for Microsoft™
Excel™, although the syntax should be similar for other spreadsheet software.
A B
1 Conductivity 1 <Enter first Conductivity reading>
2 Temperature 1 <Enter first Temperature reading>
3 Conductivity 2 <Enter second Conductivity reading>
4 Temperature 2 <Enter second Temperature reading>
5 ATC Slope =100*((10^((LOG10(B3/B1))/(B4-B2)))-1)