Ryznar Stability

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

Ryznar stability index. The Ryznar stability index (RSI) attempts to correlate an empirical database of scale thickness observed in municipal water systems to the water chemistry. Like the LSI, the RSI has its basis in the concept of saturation level. Ryznar attempted to quantify the relationship between calcium carbonate saturation state and scale formation. The Ryznar index takes the form 

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). 

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. 

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

LSI Langelier Saturation Index RSI Ryznar Stability Index 

Actual Calculated Langelier saturation Ryznar stability 

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  

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

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. 

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). 

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. 

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