Langelier Saturation Index Calculator

This calculator helps you determine the scaling potential of the water by using the Langelier Saturation Index.

Give the values of your water analysis. All the fields with * are required.

Table 1: Input table
 pH * Conductivity / TDS * mg/L ppm TDS S/cm mS/cm microS/cm ohm.cm ohm.m [Ca2+] * mg/L g/m3 ppm mol/L mmol/L eq/L meq/L [HCO3-] * mg/L g/m3 ppm mol/L mmol/L eq/L meq/L Water temperature * degree C degree F Kelvin

If you do not have a water analysis you can use the values in table 2. Click on a button at the bottom of table 2

 pH = 7.7 8 8.6 TDS = 20 34483 273 mg/l [Ca2+] = 5 400 49 mg/l [HCO3-] = 10 140 121 mg/l T = 20 20 20 degree C
Table 3: Results Langelier Saturation Index
 pHs LSI Indication based on Langelier (1936) Indication based on improved Langelier by Carrier (1965)
The Langelier Saturation Index formula is

The indications for the LSI and the improved LSI by Carrier are based on the following values:

 LSI Indication LSI<0 Water is undersaturated with respect to calcium carbonate. Undersaturated water has a tendency to remove existing calcium carbonate protective coatings in pipelines and equipment. LSI=0 Water is considered to be neutral. Neither scale-forming nor scale removing. LSI>0 Water is supersaturated with respect to calcium carbonate (CaCO3) and scale forming may occur.
 LSI (Carrier) Indication -2,0<-0,5 Serious corrosion -0,5<0 Slightly corrosion but non-scale forming LSI = 0,0 Balanced but pitting corrosion possible 0,0<0,5 Sligthly scale forming and corrosive 0,5<2 Scale forming but non corrosive
References:

[1] : Kevin Rafferty, Scaling in geothermal heat pump systems, U.S. Department of Energy (july 1999)
[2] : Metcalf and Eddy, Wastewater Engineering Treatment and Reuse 2003

Explanation of the Langelier Saturation formula.

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