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Myron L PS6 User 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.