Requirements On The Coolant; Table 22: Electrochemical Series / Standard Potentials Against Hydrogen; Table 23: Requirements On The Coolant - KEB COMBIVERT H6 Series Instructions For Use Manual

cOOLING SySTEM
Material Generated Ion
Magnesium Mg
Titan Ti
Aluminium Al
Manganese Mn
Zinc Zn
Chrome Cr
Iron Fe
Cadmium Cd
Table 22: Electrochemical series / standard potentials against hydrogen

5.1.3 Requirements on the coolant

The requirements on the coolant are depending on the ambient conditions, as well as
from the used cooling system. General requirements on the coolant:
Requirements
Suspended particles
pH-value
Abrasive substances
Copper cuttings
Hard water
Soft water
Frost protection
Corrosion protection
Table 23: Requirements on the coolant
Standard poten-
tial
-2,38V
2+
-1.75 V
2+
-1.67 V
3+
-1.05 V
2+
-0.76 V
2+
-0.71 V
3+
-0.44 V
2+
-0.40 V
2+
Description
The size and the proportion of suspended particles in the cooling water should not
exceed the following values: < 100 μm < 10 mg per liter.
Aluminum is particularly corroded by lixiviums and salts. The optimal pH value for
aluminum should be in the range of 7.5... 8.0.
Abrasive substances as used in abrasive (quartz sand), clogging the cooling circuit.
Copper cuttings can attach the aluminum and this leads to a galvanic corrosion.
Copper should not be used together with aluminum due to electro-chemical voltage
difference.
Cooling water may not cause scale deposits or loose excretions. It should have a
low total hardness (<20°dH) especially carbon hardness.
Soft water (<7°dH) corrodes the material.
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.
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.
Material Generated Ion
Iron Fe
Hydrogen 2H
Copper Cu
Carbon C
2+
Silver Ag
Platinum Pt
Gold Au
Gold Au
Standard poten-
tial
-0.037 V
3+
0.00 V
+
0.34 V
2+
0.74 V
0.80 V
+
1.20 V
2+
1.42 V
3+
1.69 V
+
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