Siemens 1FT7 Configuration Manual page 59

Note
The inhibitor is not required if it ensured that the concentration of Antifrogen N is > 20%.
Derating is not required for antifreeze protection components < 30 %.
Biocide
Closed cooling circuits with soft water are susceptible to microbes. The risk of corrosion
caused by microbes is virtually non-existent in chlorinated drinking water systems.
Antifrogen N has a biocidal effect even at the minimum required concentration of > 20 %.
No strain of bacteria can survive if >20 % Antifrogen N is added.
The suitability of a biocide depends on the type of microbe. The following types of microbes
are encountered in practice:
● Slime-forming bacteria
● Corrosive bacteria
● Iron-depositing bacteria
At least one water analysis per annum is recommended to determine the number of bacterial
colonies. Suitable biocides are available from the manufacturer Nalco for example. The
manufacturer's recommendations must be followed regarding the concentration and
compatibility with any inhibitor used.
NOTICE
Biocides and Antifrogen N must not be mixed.
There are other manufacturers of chemical additives in the market. Equivalent products from
other manufacturers may be used. The suitability must be checked by testing.
Other coolants (not water-based)
When using other coolants (e.g. oil, cooling lubricating medium) de-rating may be required in
order that the thermal motor limit is not exceeded. The derating can be determined using the
following data at a temperature of 30 °C:
Density
Specific thermal capacitance c
Thermal conductivity
Kinematic viscosity
Flow rate
1FT7 Synchronous Motors
Configuration Manual, (PFT7S) 01/2009, 6SN1197-0AD13-0BP2
ρ [kg/m ]
3
[J/(kg•K)]
ρ
λ [W/(K•m)]
ν [m /s]
2
V [rpm]
Mechanical properties of the motors
3.2 Liquid cooling
59