LaMotte CORROSION CONTROL Test Kit User Manual
Page 4
IN TRO DUC TION
A formula developed by Dr. Wilfred F. Langelier, of the University of
California at Berkeley, is used to keep potable waters in balance to prevent
corrosion on the one hand, and scale formation, on the other. This
formulation is known variously as the “Saturation Index” or the “Langelier
Equation”. It is stated as follows:
TF + TDSF - CF - AF = pHS
pH - pHS = Saturation Index
In this equation, the pH is read from a sample of water using the pocket
pH meter, and is recorded on the worksheet directly as pH units.
Temperature, Calcium Hardness, Alkalinity, and Total Dissolved Solid test
procedures are performed on the sample, the correct factor for each result is
taken from table on page 4, and the results are recorded on the worksheet.
Temperature and Total Dissolved Solids factors are added together.
Alkalinity and Calcium Hardness factors are subtracted from this sum. The
result is the solubility pH or pHS. pHS is then subtracted from measured
pH to give the corrision index, also known as the saturation index or
Langlier index.
NOTE:
Phosphate testing is included in this kit, however, phosphate
results are not required to calculate a Saturation Index. The test is included
if you add a phosphating compound to inhibit corrosion. See page 11 for
procedure.
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