The water of each area is affected by its geography. During the hydrological cycle, water meets rocks from which inorganic salts dissolve. These salts together with the salts leached from the soil and sediments form the chemical composition of water.

Water quality significantly affects the mechanical equipment and plumbing of industries, hotels, and homes, with two mechanisms: sedimentation and corrosion.

Deposits depend on water composition, thermodynamic effects, and corrosion. They are distinguished in:

• Επικαθήσεις κρυστάλλωσης, που οφείλονται στην μείωση της διαλυτότητας αλάτων, η διαλυτότητα των οποίων είναι αντίστροφα ανάλογη με τη θερμοκρασία (πχ CaCO₃). Αποτελούν τη συνηθέστερη μορφή επικαθήσεων.

• Crystallization deposits, due to the reduction of the solubility of salts, the solubility of which is inversely proportional to the temperature (ex. CaCO3). They are the most common form of sedimentation.

• Particulate matter, due to the deposition of particles that exist or are created in water. Chemical reaction settlements, due to reactions that occur on the surface but without the surface material participating in the reaction.

• Corrosion deposits due to surface corrosion products.

• Biological deposits due to deposits and growth of microorganisms on surfaces such as algae, bacteria, etc.

The Langelier Saturation Index (LSI) and the Ryznar Stability Index (SI) are used to determine the likelihood of calcium carbonate deposition:

LSI = pH – pH_s, όπου

pH_s = pK_a2 - pK_sp + p[Ca²⁺] + p[HCO₃^-] - logγ_Ca - logγ_ΗCO3

SI = 2pH_s – pH

If the LSI gets negative values this is an indication of corrosion (especially for values less than -0.5). Positive values are respectively an indication of sedimentation (especially for values greater than 0.5). SI values greater than 7 are an indication of corrosion, while values less than 6 are an indication of deposition.

Dealing with deposits: The first step is to identify the deposits. This is done by examining the water and sediments. Then a method is selected based on the type of settling.

Calcium carbonate deposits, which are also the most common, are treated with:

• growth inhibitors of nucleating crystals, such as polyacrylates, polymethacrylates, etc.

• dispersants, which do not allow agglomerations

• complexes, which bind Ca²⁺ions

• by softening, ex. the use of ion exchange resins that bind Ca²⁺ions

Consult HELLASCHEMfor:

• Water analyzes

• Metallography analyzes of materials

• Services in food, chemical, cleaning, cosmetics, hotels, etc.