Instruction book 
2920 1472 03    40 
 
  C : depends on the calcium hardness (ppm CaCO
3
). 
 
  D : depends on the HCO
3
-
 concentration or M-alkalinity (mval/l). 
 
  The values from A, B, C and D are found in the table below. 
 
 
Total 
dissolved 
solids 
  Temperature    Ca-
hardness 
  M-Alkalinity   
 (mg/l)  A  (°C)  B  (ppm 
CaCO3) 
C (mval/l) D 
50 - 300  0.1  0 - 1  2.6  10 - 11  0.6  0.20 - 0.22  1.0 
400 - 
1000 
0.2  2 - 6  2.5  12 - 13  0.7  0.24 - 0.26  1.1 
    7 - 9  2.4  14 - 17  0.8  0.28 - 0.34  1.2 
    10 - 13  2.3  18 - 22  0.9  0.36 - 0.44  1.3 
    14 - 17  2.2  23 - 27  1.0  0.46 - 0.54  1.4 
    18 - 21  2.1  28 - 34  1.1  0.56 - 0.70  1.5 
    22 - 27  2.0  35 - 43  1.2  0.72 - 0.88  1.6 
    28 - 31  1.9  44 - 55  1.3  0.90 - 1.10  1.7 
    32 - 37  1.8  56 - 69  1.4  1.12 - 1.38  1.8 
    38 - 44  1.7  70 - 87  1.5  1.40 - 1.76  1.9 
    45 - 50  1.6  88 - 110  1.6  1.78 - 2.20  2.0 
    51 - 56  1.5  111 - 138  1.7  2.22 - 2.78  2.1 
    57 - 63  1.4  138 - 174  1.8  2.80 - 3.54  2.2 
    64 - 71  1.3  175 - 220  1.9  3.54 - 4.40  2.3 
    72 - 80  1.2  230 - 270  2.0  4.6 - 5.4  2.4 
        280 - 340  2.1  5.6 - 7.0  2.5 
        350 - 430  2.2  7.2 - 8.8  2.6 
        440 - 550  2.3  9.0 - 11.0  2.7 
        560 - 690  2.4  11.2 - 13.8  2.8 
        700 - 870  2.5  14.0 - 17.6  2.9 
        880 - 
1000 
2.6  17.8 - 20.0  3.0 
 
The interpretation of the values obtained is : 
 
    RSI   <  6  boiler scale formation 
    RSI  6 – 7  neutral water 
    RSI   >  7  corrosive water