Atlas Copco ZT 55 - Page 92

Symbol Explanation
A Depends on the total solids concentration (mg/l)
B Depends on the highest cooling water temperature (˚C/˚F), (T=65 ˚C/149 ˚F)
C Depends on the calcium hardness (ppm CaCO
3
)
D
Depends on the HCO
3
-
concentration or M-alkalinity (mval/l)
The values of A, B, C and D can be found in the following table.
Total dissolved
solids (mg/l)
A Temperature
(˚C)
B Ca-hardness (ppm
CaCO
3
)
C M-alkalinity (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
Interpretation of the value obtained
RSI Water condition Action
RSI<3.9 Very high scale formation Water cannot be used.
4.0<RSI<5.5 High boiler scale formation Regular inspection and descaling operation
necessary.
5.6<RSI<6.2 Slight boiler scale formation Water treatment not necessary.
Occasional inspection recommended.
6.3<RSI<6.8 Neutral water Water treatment not necessary.
Occasional inspection recommended.
6.9<RSI<7.5 Slight corrosion at higher
temperature
Water treatment not necessary.
Occasional inspection recommended.
Instruction book
91