Does Hach have a method for measuring Langelier & Aggressive Indices?

Document ID

Document ID TE299

Published Date

Published Date 25/01/2018
Question
Does Hach have a method for measuring Langelier & Aggressive Indices?
Summary
Hach method for measuring Langelier & Aggressive Indices
Answer
The Langelier Saturation Index (LI), a measure of a solution’s ability to dissolve or deposit calcium carbonate, is often used as an indicator of the corrosivity of water. The index is not related directly to corrosion, but is related to the deposition of a calcium carbonate film or scale; this covering can insulate pipes, boilers and other components of a system from contact with water. When no protective scale is formed, water is considered to be aggressive and corrosion can occur. The Langelier Saturation Index can be calculated easily by using Hach products to determine the pH of calcium carbonate saturation (pH) and the actual pH of a solution. Using a simple formula, the pH is derived from the values for calcium hardness, total alkalinity at pH 4.5, temperature and total filterable residue (total dissolved solids). All of these procedures are included in the Hach Water Analysis Handbook.