Alkalinity

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
10-100 ppm as CaCO3 (Total) 10 ppm Acid Titrant with pH Indicator K-9810
50-500 ppm as CaCO3 (Total) 50 ppm Acid Titrant with pH Indicator K-9815
100-1000 ppm as CaCO3 (Total) 100 ppm Acid Titrant with pH Indicator K-9820
100-1000 ppm as NaOH (Hydrate) 100 ppm Acid Titrant with pH Indicator K-4710

Methods

 

The alkalinity of water is a measurement of its buffering capacity. Alkalinity of natural waters is typically a combination of bicarbonate, carbonate, and hydroxide ions. Sewage and wastewaters usually exhibit higher alkalinities due to the presence of silicates and phosphates. 

 

Alkalinity inhibits corrosion in boiler and cooling waters. It is also measured as a means of controlling water and wastewater treatment processes or the quality of various process waters.

 

Alkalinity (total)

References: ASTM D 1067-06, Acidity or Alkalinity of Water, Test Method B. APHA Standard Methods, 22nd ed., Method 2320 B - 1997.  USEPA Methods for Chemical Analysis of Water and Wastes, Method 310.1 (1983).

 

CHEMetrics' total alkalinity tests determine total or M alkalinity using a hydrochloric acid titrant and a bromocresol green/methyl red indicator. The end point of the titration occurs at pH 4.5. Results are expressed as ppm (mg/L) CaCO3.

 

Alkalinity (hydrate)

References: Developed with Calgon Corporation. APHA Standard Methods, 22nd ed., Method 2320 B - 1997.

 

Hydrate alkalinity is a component of total alkalinity. Boiler operators must maintain relatively high hydrate alkalinity levels when phosphate cycle treatments are used to ensure the formation of softer, more easily removable deposits. This specific test for hydrate alkalinity provides a more accurate value than the calculation method.

 

For hydrate alkalinity, CHEMetrics developed a titrimetric method that uses a hydrochloric acid titrant with a phenolphthalein indicator. The end point of the titration occurs at pH 8.3. Barium chloride is added to the sample to prevent interference from carbonate and bicarbonate alkalinity. Results are expressed as ppm (mg/L) NaOH.