SEW-Eurodrive M1 N Series, Руководство по сборке и эксплуатации

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5
Installation/assembly
Cooling coil
Assembly and Operating Instructions – M1..N Series Single-Stage Helical Gear Units
57
5.14.2 Requirements on the water quality
INFORMATION
Contact SEW‑EURODRIVE if you use cooling media such as brackish water or pro-
cess water.
The following requirements on the water quality are recommendations. In exceptional
cases, certain concentrations of substances of content might cause unforeseen reac-
tions.
The quality of the water as well as its substances are important factors for assessing
the cooling water available for water cooling cartridges. The water quality is deter-
mined by the water hardness and the pH value of the water.
Water hardness
Water hardness is defined by the amount of hardeners (carbonates and bicarbonates)
in the water. Hardeners accumulate on the surface of the water cooling cartridge in
particular at high temperatures and in this way impair the performance. Take these de-
posits into account when selecting the water cooling cartridge for extremely hard wa-
ter.
The following table shows the classification of German degrees of hardness to water
quality °dH:
Degree of hardness
1)
Water quality
0 – 5 °dH Very soft water
5 – 10 °dH Soft water
10 – 20 °dH Medium hard water
20 – 30 °dH Hard water
> 30 °dH Very hard water
1) 10 mg/l of hardener corresponds to 1 °dH
pH value
• The water cooling cartridge partially consists of a copper and nickel alloy, to which
the following applies:
→ Corrosion problems when pH value < 6
• With alkaline water:
→ Corrosion problems when water hardness < 6°dH
Smaller values can cause corrosion due to free carbonic acid.
The following table describes the classification of the water quality based on the
pH value:
pH Value Water quality
4.5 Very acidic
4.5 – 6.0 Acidic
6.0 – 6.8 Slightly acidic
7.0 Neutral
7.2 – 7.7 Slightly alkaline
7.7 – 8.2 Alkaline
8.2 Very alkaline
29203856/EN – 03/2020