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The materials used in the Oventrop fresh water and
dwelling stations are selected and processed in
accordance with strict quality specifications. The plate
material used (stainless steel 1.4401) for the heat
exchangers has proven itself over the long term in
potable water applications. Nevertheless, depending on
the water quality, especially with high chloride
concentrations > 100 mg/l, it is possible that leaks may
form due to corrosion on the heat exchangers.
It is therefore very important that the system designer
and/or operator ensures that the fresh water and
dwelling stations are only operated with potable water
whose chemical composition does not have a corrosive
effect on the components.
If necessary, coordinate with the local water supply
company.
Water quality requirements
CONSTITUENTS
Chlorides (Cl
) at 60 °C
-
See chart on next page!
Hydrogen carbonate (HCO
Sulphate (SO
)
2-
4
HCO
/ SO
-
2-
3
4
Electrical conductivity at 20°C
pH
In general, a low pH value (below 6)
increases the risk of corrosion and a
high pH value (above 7.5) reduces
the risk of corrosion.
Free chlorine (Cl
)
2
Ammonium (NH
)
+
4
Hydrogen sulphide (H
S)
2
Free (aggressive) carbon dioxide
(CO
)
2
Nitrate (NO
)
-
3
EXPLANATIONS:
The chemical composition of potable water can be subject to temporal fluctuations.
CONCENTRATION
(mg/l or ppm)
< 100
100 - 150
> 150
)
< 70
-
3
70 - 300
> 300
< 70
> 70
> 1.0
< 1.0
< 50 µS/cm
50 - 500 µS/cm
> 500 µS/cm
< 6.0
6.0 - 7.5
7.5 - 9.0
9.0 - 9.5
>9.5
< 1
> 1
< 2
2 - 20
> 20
< 0.05
> 0.05
< 5
5 - 20
> 20
< 100
> 100
+
Good resistance under normal conditions
0
Corrosion may occur
-
Use not recommended
Fresh water station Regumaq X-45
Notes on corrosion protection
The following table contains limit values of potable water
constituents when using heat exchangers with different
brazing materials (copper, nickel or stainless steel).
Particular attention should be paid to the fact that there
can be interactions between certain water constituents
that can lead to special stresses on the material.
This includes, among other things, the combination of
hydrogen carbonate with chloride and / or sulphate (see
next page).
The selection of a suitable heat exchanger must therefore
be made depending on the water quality. Corresponding
analyses are provided by the local water supply company.
Stainless steel heat exchanger brazed with:
NICKEL /
STAINLESS
COPPER
STEEL
+
-
-
0
+
0
+
-
+
-
0
+
0
0
0
+
0
0
+
-
+
0
-
+
-
+
0
-
+
0
COPPER
with protec-
tive layer
+
+
-
+
-
0
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
0
+
+
+
+
+
+
+
+
0
+
+
-
0
+
+
+
+
+
-
+
+
+
0
+
+
+
+
+
+
+
+
+
+
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