LaMotte CORROSION CONTROL Test Kit User Manual

TA BLE OF CON TENTS

Introduction.................................................................................. 4

Corrosivity Index Calculations ...................................................... 5

Alkalinity...................................................................................... 7

Phenolphthalein............................................................................. 7

Total Alkalinity .............................................................................. 8

Calcium Hardness ......................................................................... 9

Testr pH10 ............................................................................... 10

Temperature................................................................................ 10

TDSTest r Low ............................................................................ 10

Phosphate in Water..................................................................... 12

Recommended Standardization Practices ...................................... 14

3

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.

4

CORROSIVITY IN DEX CAL CU LA TIONS

The Corrosivity Index (Langelier’s Saturation) is used to determine
whether a water supply will support and deposit calcium carbonate. This
deposit acts as a buffer against leaching of various metals within the
distribution system; the primary concern of which is lead.

The Corrosivity Index is figured using five basic factors: pH, calcium
hardness, total alkalinity, temperature, and total dissolved solids. The
resulting formula is used to calculate the Corrosivity Index as follows:

TF + TDSF - CF - AF = pHS

Corrosivity Index = pH - pHS

With this information a water supply operator can quickly calculate the
Corrosivity Index for any system.

pH = pH Factor
TF = Temperature Factor

CF = Calcium Hardness Factor

AF = Alkalinity Factor

TDSF = Total Dissolved Solids

Factor

The Corrosivity Index should be maintained at a positive value between 0
and +0.5.

If the Corrosivity Index is 0, the water is perfectly balanced.

If the Corrosivity Index is negative, corrosion tendencies are predicted.

If the Corrosivity Index is positive, scale forming tendencies are predicted.

NOTE: Use supplied worksheets for Index Calculations.

Read directly with pH tester

Read temperature in °C, use Index
Calculation Chart

Titrate for calcium hardness, use
Index Calculation Chart

Titrate for total Alkalinity, use
Index Calculation Chart

Use Pocketester and Index
Calculation Chart

5