Myron L PS6 - Manual (Page 49)

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XXVI. ADDENDUM: NEW LSI & hARDNESS CALCULATOR
The new LSI calculator makes it easy to analyze the scaling nature of
water in the lab or in the field. Using a calcium carbonate saturation
index algorithm developed by Dr. Wilfred Langelier in 1936, the
calculator computes the saturation index of a sample based on
measured and inferred values for pH, temperature, hardness and
alkalinity. You can then change any of these values in “User” adjust
mode to analyze the effect of the change on water balance. “User”
mode also allows you to input measured values for alkalinity and
hardness as determined by other independent testing for a precise
saturation index value.
The PS6SI LSI calculator computes a saturation index value using the
following formula:
SI = PH + TF + CF + AF – 12.1
Where:
PH is the measured value of pH in pH units as determined by the PS6SI
TF = 0.0117 x Temp – 0.4116
CF = 0.4341 x ln(Hrd) – 0.3926
AF = 0.4341 x ln(AL) – 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
how to Use the PS6SI LSI Calculator
In LSI Calculator mode, accept all PS6SI variable values to obtain the
PS6SI saturation index value. Once the PS6SI saturation index value
is displayed, you can enter “User” mode to change values for pH,
temperature, hardness (ppm or grains), and alkalinity (ppm CaCO
3
),
then recalculate the saturation index based on those changes. The
most accurate way to generate a saturation index value is to accept
PS6SI measured values for pH and temperature and input values in
“User” mode for hardness and alkalinity based on titration testing.
NOTE: You can exit the LSI calculator at any time by pressing any of
the parameter keys or by letting the unit time out.