User manual

2920 1475 00
30
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 Action
RSI < 3.9 Very high scale formation Water cannot be used
4.0 < RSI < 5.5 High boiler scale formation Regular control 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
7.6 < RSI < 9.0 Strong corrosion Regular control necessary, use of corrosion inhibitor
recommended
9.1 < RSI < 11 Very strong corrosion Regular control necessary, use of corrosion inhibitor required
RSI > 11 Very strong corrosion in complete
water system Water should not be used
This table indicates that distilled or demineralised water should
never be used, as their RSI is > 11.
The RSI only indicates 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 a specialist.
pH
The effect of pH is already calculated in the Rysnar index, but
the pH itself has some additional limitations : 6.8 < pH
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.
In a closed system, the following limits apply: TDS < 3000
mg/l (< 3800 µS/cm)
For an open system, the following limits apply: TDS < 450
mg/l (< 580 µS/cm)
Chlorides (Cl
-
)
Chloride ions will create pitting corrosion on stainless steel.
Their concentration should be limited :
Closed cooling system : Chlorides < 500 ppm
Open cooling system : Chlorides < 150 ppm
However, if the water is scaling, lower limits should be used.
(See The Rysnar stability index (RSI)).
Free chlorine (Cl
2
)
Continuously, a level of 0.5 ppm should not be exceeded.
For shock treatments, a maximum limit of 2 ppm for maximum
30 minutes/day applies.