Instruction book
2920 1472 03 39
Reference Description
14 Torques for steel (Fe) or brass (CuZn) bolts
15 Consult the Instruction book before greasing
16 Switch off the voltage before removing the protecting cover inside the electric cabinet
17 Oil the gaskets, screw on the filters and tighten by hand (approx. one half turn)
18 Consult the Instruction book before maintenance or repair
19 Cooling water outlet
20 Cooling water inlet
Figs. 2.9 and 2.10 Pictographs
2.5 Cooling water requirements
The cooling water quality must meet certain minimum requirements.
No general recommendation can encompass the effects of all combinations of the various compounds,
solids and gases typically found in cooling water in interaction with different materials.
This recommendation is a general guide line for acceptable coolant quality.
2.5.1 Type of the system
Closed system
In a closed system, the same cooling water is circulating through a system without contact with air.
Open system
An open system is a pass-through system, or a circulating system with a cooling tower. In the latter
case, the composition of the water that enters the cooler must be considered, and not the composition
of the make-up water. Due to the evaporative effect in the cooling tower, much higher concentrations
of ions can be obtained in the circulating water than in the make-up water.
2.5.2 Cooling water parameters
The Ryznar stability index (RSI)
The Ryznar Index (RSI) is a parameter for predicting whether water will tend to dissolve or precipitate
calcium carbonate. The adhesion of scaling deposits and their effect are different on different
materials, but the equilibrium of the water (scaling or corrosive) is only determined by its actual pH
value and by the saturation pH value (pHs). The saturation pH value is determined by the relationship
between the calcium hardness, the total alkalinity, the total solids concentration and the temperature.
The Ryznar Index is calculated as follows:
RSI = 2*pH
s
- pH
where pH = measured pH (at room temperature) of water sample
pH
s
= pH at saturation
The pH
s
is calculated by using :
pH
s
= (9.3 + A + B) - (C + D)
A : depends on the total solids concentration (mg/l).
B : depends on the highest cooling water temperature (°C).
For Z units take T = 65°C
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