electro-chemical voltage series / standard potentials against hydrogenMaterial generated Ion Standard poten-tialMaterial generated Ion Standard poten-tialcontinued on the next pageCadmium Cd 2+ -0.40 V Gold Au + 1.69 VCobald Co2+ -0.28 VTable 6: Electro-chemical voltage seriesWe recommend the use of stainless steel or nickel plated screw connection.Other materials must be examined in each case before employment. The specific caseof application must be checked by the customer in tuning of the complete cooling circuitand must be classified according to the used materials. With hoses and seals take carethat halogen-free materials are used.A liability for occuring damages by wrongly used materials and from this resulting corro-sion cannot be taken over!c.1.3 requirements on the coolantThe requirements on the coolant are depending on the ambient conditions, as well asfrom the used cooling system. General requirements on the coolant:Standards TrinkwV 2001, DIN eN 12502 part 1-5, DIN 50930 part 6, DVGW work sheet W216VGBCooling water direc-tiveThe VGB cooling water directive (VGB-R 455 P) contains instructions about commonprocess technology of the cooling. Particulary the interactions between cooling waterand components of the cooling system are described.pH-value The optimal pH-value should be in the range of 7.5…8.0.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. It shall have a lowtotal hardness (<20°d) especially carbon hardness.Soft water Soft water (<7°dH) corrodes the material.Frost protection An appropriate antifreeze must be used for applications when the heat sink or thecoolant is exposed temperatures below zero. Use only products of one manufacturerfor a better compatibility with other additives. We recommend the antifreeze Anti-frogenN of the company Clariant with a maximum volume percent of 52%.Corrosion protection Additives can be used as corrosion protection. In connection with frost protection theantifreeze must have a concentration of 20…25 Vol %, in order to avoid a change ofthe additives.Table 7: Requirements on the coolant72ANNex - cOOLING SySTeM
