Conditions and treatment of cooling fresh water
>To prevent scale formations,sludge formation and acid corrosion.
Why treatment is required ?
1.fresh water cause scale deposits on heated surface .We can use distill water to prevent it may still cause pitting (chromate are used ) and erosion and become acidic with ude.
2.Some times acidic corrosion happens;so to prevent it,sodium nitrated is used (i.e ,safe for handling,non-toxic,non-dangerous and contain a ph buffer ) They form a thin passive oxide layer.
3.To protect from sludge formation.
1.Corrosion Inhibitor and alkaline agents are used to protect metal surfaces.These must be soluble in water but cam not be poisonous,if a domestic fresh water generator exists in the system..
2.Chemical additives such as Nitrates,borates may be used (They create a thin passive oxide surface layee on most metals ) .They do not harm water seal rings but will attack any Zinc present.Witg this arrangement ,Zinc Anodes are not fitted.
3.Soluble Emulsion Oils may also be used where no narrow passage exist.They form a greasy protective film which adheres to the surfaces and prevents corrosion.
Emulsion oils must be maintained within close concentration limits and the system kept clean.