Siemens SIMOTICS FD 1LH1, Operating Instructions & Installation Instructions

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Biocides
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 when the appropriate quantity of anti-freeze is added. The
following microbes can occur:
● Bacteria that cause the formation of slime
● Corrosive bacteria
● Bacteria that cause deposits of iron
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. You can purchase
suitable biocides, for example from Nalco.
Note
Determining the appropriate biocide
The type of bacteria determines the biocide. Antifreeze already has a biocidal effect for the
minimum concentration specified above.
● The manufacturer's recommendations must be followed in regard to the dosage and
compatibility with any inhibitor that might be used.
● Never mix biocides and anti-freeze.
4.5.4 Cooling capacity derating
If you use antifreeze, then observe the cooling capacity derating factor, dependent on the
antifreeze concentration, as listed in the table.
Anti-freeze Concentration Cooling capacity derating factor
Antifrogen N
Varidos FSK
Antifrogen L 20% 0%
25% 0%
30% 0%
35% 2%
40% 4%
45% 5%
Antifrogen N / Varidos FSK ≙ ethylene glycol
Antifrogen L ≙ propylene glycol
Note
Order-specific agreements
Order-specific agreements regarding the cooling water specification can deviate from the
cooling water specification mentioned.
Preparations for use
4.5 Coolant specification
SIMOTICS FD 1LH1
36
Operating Instructions 01/2019