Optimal cooling water parameters

What Cooling Water Parameters Should We Control to Minimize the Risk of Scale and Deposit Formation?

Optimally treating cooling water is crucial for minimizing the risk of deposits, scale, and corrosion (rust) in cooling systems. Below are the key chemical parameters that should be monitored:

1. Water Hardness (CaCO₃):
   • Optimal Range: 80-120 ppm (mg/L).
   • Excessive hardness can lead to scale formation (e.g., calcium carbonate), while very low hardness increases corrosion risk.
   • Control: Regular laboratory tests and, if hardness is too high, the use of scale inhibitors.
2. Water pH:
   • Optimal Range: 7.0-8.5.
   • pH levels below 7 can accelerate corrosion, while higher values encourage scale formation.
   • Control: Daily pH testing, with pH regulators (acids/bases) as needed.
3. Alkalinity:
   • Optimal Range: 100-300 ppm (as CaCO₃).
   • Higher alkalinity promotes calcium deposit formation, while low alkalinity may favor corrosion.
   • Control: Alkalinity testing and the addition of regulating agents as necessary.
4. Chlorine and Other Oxidizing Agents:
   • Optimal Range: 0.5-1.5 ppm for free chlorine.
   • Chlorine has antibacterial effects, but excessive levels lead to corrosion.
   • Control: Chlorine levels monitored with DPD or amperometric tests.
5. Electrical Conductivity:
   • Optimal Range: 500-2000 µS/cm (system dependent).
   • High conductivity indicates high salt concentration, which promotes deposit formation and corrosion.
   • Control: Regular conductivity measurements and blowdown (partial drainage and refill with fresh water).
6. Oxygen Content:
   • Oxygen in cooling water fosters corrosion.
   • Control: Use corrosion inhibitors (e.g., sodium sulfite) to reduce oxygen content.
7. Iron and Copper Concentration:
   • Optimal Range: <0.5 ppm for iron and copper.
   • Higher concentrations may indicate internal system corrosion.
8. Chemical Agents and Inhibitors:
   • Scale Inhibitors: Polyphosphates, organic phosphates, phosphonic acid (prevents calcium salt deposits).
   • Corrosion Inhibitors: Molybdates, nitrites, zinc phosphates, silicon compounds.
   • Biocides: Chlorine, bromine, isothiazolinones – used for biological control (bacteria, algae).
   • Dispersants: Help keep suspended particles in water to prevent sludge formation.

What Products to Use?

• Corrosion and Scale Inhibitors: Prevent scale buildup and rust formation.
• Biocides: Control microorganism growth (bacteria, algae) in the system.
• pH Regulators: Acids or bases, depending on pH readings.

For efficient and effective water treatment, regular monitoring and adjustments based on these parameters are essential to maintain a well-functioning cooling system.