76
WATer-cOOLeD DeVIceS
Material
formed ion
Standard poten-
tial
Material
formed ion
Standard poten-
tial
Chrome
Cr3+
-0.71 V
Platinum
Pt2+
1.20 V
Iron
Fe2+
-0.44 V
Gold
Au3+
1.42 V
Cadmium
Cd2+
-0.40 V
Gold
Au+
1.69 V
Cobald
Co2+
-0.28 V
Table 38:
Electrochemical series / standard potentials against hydrogen
5.1.3 requirements for the coolant
The requirements for the coolant depend on the ambient conditions as well as the used
cooling system.
General requirements for the coolant:
requirement
Description
Standards
Corrosion protection according to
, water treatment and use of ma-
terials in cooling systems according to
VGB
Cooling water directive
The VGB cooling water directive (
) contains instructions about com-
mon process technology of the cooling. Particulary the interactions between cool-
ing water and components of the cooling system are described.
Abrasive substances
Abrasive substances as used in abrasive (quartz sand), clogging the cooling circuit.
Hard water
Cooling water may not cause scale deposits or loose excretions. The total hard-
ness should be between 7...20 °dH, the carbon hardness between 3...10 °dH.
Soft water
Soft water (<7°dH) corrodes the material.
Frost protection
An appropriate antifreeze must be used for applications when the heat sink or the
coolant is exposed temperatures below zero. Use only products of one manufac-
turer for a better compatibility with other additives.
KEB recommends the antifreeze Antifrogen N from Clariant with a maximum vol-
ume content of 52 %.
Corrosion protection
Additives can be used as corrosion protection. In connection with frost protec-
tion the antifreeze must have a concentration of 20…25 Vol %, in order to avoid a
change of the additives.
Alternatively, an antifreeze / glycol with a concentration of 20% ... max. vol 52%
can be used. If antifreeze is used, the water does not need to be provided with
additional additives.
Table 39:
Coolant requirements for water coolers
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