Atlas Copco GR110 Instruction Book page 21

Instruction book
The interpretation of the values obtained is :
RSI < 6 boiler scale formation
RSI 6 - 7 neutral water
RSI > 7 corrosive water
A more detailed interpretation follows below :
RSI Tendency of the water
RSI < 3.9 Very high scale formation
4.0 < RSI < 5.5 High boiler scale formation
5.6 < RSI < 6.2 Slight boiler scale formation
6.3 < RSI < 6.8 Neutral water
6.9 < RSI < 7.5 Slight corrosion at higher temperature
7.6 < RSI < 9.0 Strong corrosion
9.1 < RSI < 11 Very strong corrosion
RSI > 11 Very strong corrosion in complete water system
This table indicates that distilled or demineralised water should
never be used, as their RSI is >11.
The RSI is only indicating the equilibrium of scaling – descaling.
A cooling water showing good RSI conditions can still be
unsuitable due to other factors.
From the table above, the RSI index should be between 5.6
and 7.5, otherwise contact specialist.
pH
The effect of pH is already incalculated in the Rysnar index,
but the pH itself has some additional limitations :
GA/GR-units
Total Dissolved solids (TDS)
This is the sum of all ions in the water. It can be derived from
the dry residue after evaporation (but not including suspended
solids), or it can be estimated from the electrical conductivity.
2920 1449 00
6.8 < pH
Action
Water cannot be used
Regular control and descaling operation necessary
Water treatment not necessary
Occasional inspection recommended
Regular control necessary, use of corrosion inhibitor
recommended
Regular control necessary, use of corrosion inhibitor
required
Water should not be used
In a closed system, the following limits apply :
All units TDS < 3000 mg/l
For an open system, the following limits apply :
GA/GR-units TDS < 450 mg/l
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Chlorides (Cl )
Chloride ions will create pitting corrosion on stainless steel.
Their concentration should be limited :
Closed cooling system :
Open cooling system :
However, if the water is scaling, lower limits should be used.
(See The Rysnar stability index (RSI)).
(<3800 µS/cm)
( < 580 µS/cm)
Chlorides < 500 ppm
Chlorides < 150 ppm
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