Langelier Index
Langelier Index
(OP)
The Langelier Index is a saturation index which measures the potential to dissolve or deposit calcium carbonate. In the past it has been used, incorrectly as a corrosion index to assess corrosivity. AWWA have recommended that this practice be abandoned
My question is to what extent is the Langelier index still being used as method of control and monitoring of water quality. i.e are there any mandatory requirements in the US to measure the Langelier Index.
My question is to what extent is the Langelier index still being used as method of control and monitoring of water quality. i.e are there any mandatory requirements in the US to measure the Langelier Index.





RE: Langelier Index
Don't think anyone requires the LI us used. The LI is just one tool in the toolbox.
Regarding the comment "AWWA have recommended that this practice be abandoned", AWWA still has LI on the website:
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RE: Langelier Index
I am out in the sticks of Africa and I am being given the story that the LI and physical Marble Tests have virtually been abandoned. I am sure that is not the case and that the LI and Marble Test (together with other SI indices) are still common practice in the western world.
I am not sure what other practical means there are to assess corrosivity ?
RE: Langelier Index
http://www.alspi.com/water.pdf
Another method is to survey existing users especially the professionals like the well drillers.
RE: Langelier Index
Basically its:
CCPP = ([Ca observed] - [Ca saturation])
Generally you want a -5.0 mg/L CaCO3 or better.
Then there is another index out there called the Rynzar Stability Index (RSI).
RSI - 2pHs - pH
pH is the measured water pH
pHs is the pH at saturation in calcite or calcium carbonate
RSI < 6 = scale forming
RSI 6 to 7 = little scale or corrosion
RSI > 7 = corrosion significant
RE: Langelier Index
Orenda
RE: Langelier Index
The above link gives a good description of various indices.
RE: Langelier Index
The other comps were: Calcium Phosphate, and Magnesium Silicate saturation.