Ryznar Stability

Calcium—In general, calcium (as CaCOs) below 800 ppm should not result in calcium sulfate scale. In arid climates, however, the critical level may be much lower. For calcium carbonate scaling tendencies, calculate the Langelier Saturation Index or the Ryznar Stability Index. 

Over the years, the use and application of several different saturation indices that aid the prediction of scaling and corrosion potential in different waters have evolved to become an integral part of the business of treating and managing cooling water systems. The two most popular are the Lange-lier Saturation Index (LSI) and the Ryznar Stability Index (SI), which were both introduced more than 50 years ago. 

The most widely known of these alternative indices is probably the Ryznar Stability Index (Ryznar Index, Stability Index) (SI), which is a direct derivation of LSI and is based on observed field data. It is generally considered more useful than the LSI in water systems flowing at or above 2 ft/sec (0.6 m/sec), such as occurs in most cooling systems. 

Are the calculations for Langelier Saturation Index (LSI) or Ryznar Stability Index (SI) regularly undertaken and interpreted ... 

I I Water treatment engineers use the Langelier saturation index (LI) and Ryznar stability index (Rl) [7,2] to evaluate the scaling and corroding tendencies of water. Here is a graphical method for determining these pa-... 

Ryznar Stability RSI = 2pH - pH Total alkalinity, mg/L as CaCOj RSI < 6.5 = Water is supersaturated tends to... 

RYZNAR STABILITY INDEX - An index based on calcium carbonate pH of saturation vs. actual pH to determine scaling or corrosion tendencies of a water (R.I. = 2 pHs). 

Actual Calculated Langelier saturation Ryznar stability... 

Water with a Ryznar stability index less than 6.0 is definitely scaleforming indices of 6.0-7.0 are regarded as good for domestic waters possibly at values above 7.0, and certainly with indices above 7.5, the waters do not form a protective scale. One of the reasons for the discrepancies noted in the performance of waters with identical saturation indices lies in the buffer capacity of a water. 

LSI Langelier Saturation Index RSI Ryznar Stability Index... 

The Ryznar stability index (RSI) uses a correlation established between an empirical database of scale thickness observed in municipal water systems and associated water chemistry data. As with the LSI, the RSI has its basis in the concept of saturation level. The RSI takes the following form ... 

The empirical correlation of the Ryznar stability index can be summarized as follows ... 

The PSI is calculated in a manner similar to the Ryznar stability index. Puckorius uses an equilibrium pH rather than the actual system pH to account for the buffering effects ... 

The tendency of water to form scale or cause corrosion is measured by either the Langelier Scaling Index (LSI), which is also called the Saturation Index, or the Ryznar Stability Index (RSI), which is also called the Stability Index (Table 4.2). 

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