Siemens SINAMICS S120 Equipment Manual page 189

Anti-freeze protection
Antifrogen N (Manufacturer: Clariant) with a proportion X of 20 % < X ≤ 45 % is the anti-
freeze used. Coolants containing 45 % Antifrogen N are anti-freeze-protected down to
-30 °C.
Antifrogen N contains anti-corrosion inhibitors which permanently protect the metal in the
cooling system against corrosion.
It is particularly important to ensure that the proportion of Antifrogen N is always >20 % when
a system is refilled, otherwise the mixture becomes corrosive.
Inhibitors and Antifrogen N must not be mixed.
Biocide
Closed cooling circuits with soft water (°DH>4) are susceptible to microbes. The risk of
corrosion caused by microbes is virtually non-existent in chlorinated drinking water systems.
No strain of bacteria can survive if >20 % Antifrogen N is added.
The following types of bacteria are encountered in practice:
• Slime-forming bacteria
• Corrosive bacteria
• Iron-depositing bacteria
The type of bacteria determines the suitability of a biocide. At least one water analysis per
annum (to determine the number of bacterial colonies) is recommended. Suitable biocides
are available, for example, from Nalco (Manufacturer: Nalco).
Note
The type of bacteria determines the biocide.
The manufacturer's recommendations must be followed as regards the dosage and
compatibility with any inhibitor used.
Biocides and Antifrogen N must not be mixed.
Antifrogen N has a biocidal effect even at the minimum required concentration of >20 %.
Chassis Power Units Liquid Cooled
SINAMICS S120 Equipment Manual, Edition 12/2007, 6SL3097-2AM00-0BP4
Cooling circuit and coolant properties
8.2 Coolant definition
8-15