Solarbayer FRIWA 50, Manual

Page: 25 / 36

Code no.
907.40.62
Dated 10/2015 - 25 -
3.3 Corrosion protection
To prevent corrosion damage to plate heat exchangers, the following drinking water values
must be observed:
Maximum permitted drinking water values in conjunction with stainless steel plate
heat exchangers [SS 316/1.4404]
Copper-soldered Solid stainless steel
Chloride
1
(CL
-
) < 300 mg/l at 60°C
< 100 mg/l at 80°C < 300 mg/l at 60°C
< 100 mg/l at 80°C
Sulphate
1
(SO
4
2-
) < 70 mg/l < 100 mg/l
Nitrate (NO3-) < 50 mg/l
pH value 7.5 - 9.0 7.0 - 9.0
Electrical conductivity (at 25°C) 10
– 500 µS/cm
Hydrogen carbonate (HCO
3
-
) 70 -300 mg/l 60 -300 mg/l
Ratio HCO
3
-
/SO
4
2-
Ratio > 1.0 Ratio > 1.5
Ammonia (NH
4
+
) < 2 mg/l
Free chlorine gas < 1 mg/l
Sulphite < 1 mg/l
Hydrogen sulphide (H
2
S) < 0.05 mg/l
Free (aggressive) carbon dioxide
(CO
2
)
< 5 mg/l
Iron (Fe) < 0.2 mg/l
Aluminium (Al) < 0.2 mg/l
Manganese (Mn) < 0.1 mg/l
Degree of hardness >4.0° dH
1
It is not permitted to use the fresh water station if the limit values are exceeded.
To prevent pitting corrosion in the domestic installation, no new galvanised
iron material must be installed downstream in the hot water pipe of the copper-
soldered plate heat exchanger without forming a protective layer.
Solid stainless steel plate heat exchangers must be used in mixed installations
with zinc-coated iron materials.