Myron L 9PTK - Manual (Page 70)

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XXiv. alKalinity, harDness anD lsi FUnctiOns
A. Alkalinity and Hardness Titrations
The 9P uses a conductometric method of titration. This means that
instead of measuring a color or pH change, it measures the change in
conductivity when reagent is added. The way the sample solution behaves
is compared to the behavior of solutions of known alkalinity or hardness
under the same conditions. The equivalence point is determined from
the known data curve that best matches the experimental data.
B. Langelier Saturation Index
The LSI calculator and titration functions use a calcium carbonate
saturation index algorithm developed by Dr. Wilfred Langelier in 1936:
SI = PH + TF + CF + AF – 12.1
Where:
PH = pH value
TF = 0.0117 x Temperature value – 0.4116
CF = 0.4341 x ln(Hardness value) – 0.3926
AF = 0.4341 x ln(Alkalinity value) – 0.0074
The following is a general industry guideline for interpreting LSI values:
• An index between -0.5 and +0.5 indicates balanced water
• An index of more than +0.5 indicates scale-forming water
• An index below -0.5 indicates corrosive water
You can use the calculator to adjust any of the water balance
parameter variables used in the calculation to analyze the effect of the
change on water balance.
The LSI titration function generates an accurate saturation index value
that indicates the state of the system at the time the calculation is
made.
C. Hardness Units
nOte: The 9P MUST be in the HARDNESS FUNCTION or the
hardness screen (“hrd”) in LSI CALCULATOR or LSI TITRATION
mode for hardness unit preference selection.
The hardness unit preference is set simultaneously for all three
functions that capture a hardness value. That means when you set the
preference in one function, it is set for the other two functions at the
same time.