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RTW Corrosivity Index Calculator

Rothberg, Tamburini & Winsor, Inc. along with the American Water Works Association, are pleased to offer the following tool for water operators. The RTW Corrosivity Index Calculator calculates two useful corrosion indices: the Langelier Saturation Index, and the Ryznar Stability Index. Each can be independently used to determine the corrosive nature of a given influent water.

  • Langelier Index: this is an equilibrium index based on the concept of "Saturation pH", or degree of saturation with calcium carbonate.
  • Ryznar Index: this index is based on the Langelier index and incorporates an empirical correlation observed in municipal water systems between calcium carbonate buildup and water chemistry.
   
  Enter initial water characteristics    
  Measured TDS mg/L  
  Measured temperature deg C  
  Measured pH    
  Measured alk, as CaCO3 mg/L  
  Measured Ca, as CaCO3 mg/L  
  Measured Cl mg/L  
  Measured SO4 mg/L  
Question marks appear when there is unexpected
data indicating your input should be rechecked
 
  Theoretical interim water characteristics Desired
  Langelier index   >0  
  Ryznar Stability index   5.0-7.0  
   
 
   

Buy NowThe RTW Corrosivity Index Calculator is a small component of the RTW Model for Corrosion Control and Process Chemistry 4.0 available from the AWWA Bookstore. The RTW Model is a spreadsheet-based tool (Quattro Pro 8® and Microsoft Excel® 5.0 or higher) designed to help users evaluate effects of chemical additions on the stability of water and predict changes in water quality parameters, such as pH and calcium carbonate precipitation potential. It can also be used to evaluate some solids that are important in water treatment.

The RTW Model for Corrosion Control and Process Chemistry 4.0 will help you:

  • Develop corrosion control strategies
  • Define optimum conditions for coagulation processes that utilize Aluminum, Ferrous, and Ferric salts
  • Calculate impacts of pH changes due to chemical addition on Cl2 residual and TTHM concentrations
  • Predict conditions under which a water system will precipitate: Cu2(OH)2CO3, CuO, Cu(OH)2, Fe(OH)2, Fe(CO3), Fe(OH)3, and Al(OH)3 (fresh and aged)
  • Evaluate chemical treatment and dosage options, their economics, and facilities for their implementation
  • Calculate parameters such as water pH, alkalinity, CCPP , li, and DIC

Catalog Number 53043.
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