900-C Conductivity, TDS, Resistivity, Ratio, Meter - TPS

17.3 Calculating the ATC Slope of SolutionsThe conductivity of all solutions changes as the temperature of the solution changes. The ATCSlope of a solution is the amount that this Conductivity changes per degree Celsius. The ATC Slopeis dependant upon the chemicals dissolved in the solution, the concentration of those chemicals, andthe actual temperature of the solution. Consider the following examples…• A 0.02 Molar solution of KCl has a different ATC Slope to a 0.02 Molar solution of NaCl.• A 0.02 Molar solution of KCl has a different ATC Slope to a 0.01 Molar solution of the samesalt.• A 0.02 Molar solution of KCl at 25 O C has a different ATC Slope to a 0.02 Molar solution ofKCl at 15 O C.To calculate the ATC Slope of a solution…1. Set the ATC Slope for sample measurements to zero, with the following key sequence…→ F5:Configure → F3:ATC → F1:Sample → 0.00 →2. Ensure that the temperature function has been calibrated (see section 7.1). The conductivityfunction 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 totake sample measurements. Record the Conductivity and Temperature readings, once both havebecome stable.4. Warm the solution to approximately 5 O C above the temperature at which you expect to takesample measurements. Record the Conductivity and Temperature readings, once both havebecome stable.5. Apply the following formula, where C1 and T1 are the first readings taken, and C2 and T2 arethe second readings taken…C2Log C1T2 - T1ATC Slope = 100 x 10 - 16. Enter the result that is obtained as the ATC Slope of the solution.(a) If this is the ATC Slope of the sample solution to be measured…→ F5:Configure → F3:ATC → F1:Sample → [result] →(b) If this is the ATC Slope of the standard solution to be used for calibration…→ F5:Configure → F3:ATC → F2:Standard → [result] →NoteTo 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 besimilar for other spreadsheet software.49AB1 Conductivity 1 2 Temperature 1 3 Conductivity 2 4 Temperature 2 5 ATC Slope =100*((10^((LOG10(B3/B1))/(B4-B2)))-1)