Cooling water
The water chiller contains demineralised water, mixed with a little coolant.
Quality definitions of demineralised water
Section titled “Quality definitions of demineralised water”Demineralised water (demiwater) is deionised water for technical applications that need pure water. It is not suitable for drinking.
| Parameter (symbol) | Unit | Minimum | Maximum | Average |
|---|---|---|---|---|
| Conductivity at 20 °C (EC) | µS/cm | <0.2 | <0.06 | |
| Degassed conductivity at 20 °C (EC) | µS/cm | <0.2 | <0.06 | |
| Silicate (SiO2) | mg/l | <0.03 | <0.06 | |
| Total dissolved solids (TDS) | mg/l | N.A. | N.A. | |
| Iron (Fe) | mg/l | <0.1 | <0.005 | |
| Copper (Cu) | mg/l | <0.05 | <0.005 | |
| Ammonia (NH3) | mg/l | <2 | <0.010 | |
| Total organic carbon (TOC) | mg/l | N.A. | 0.002 - 0.010 | |
| Turbidity | NTU | N.A. | N.A. | |
| Sodium (Na+) | mg/l | N.A. | <0.020 | |
| Sulphate (SO4) | mg/l | N.A. | N.A. | |
| Chloride (Cl-) | mg/l | N.A. | <0.010 | |
| Free / total chlorine (Cl2) | mg/l | N.A. | N.A. | |
| Temperature | °C | 3 | 40 | 12 |
| Calcium (Ca) | mg/l | N.A. | <0.010 | |
| Magnesium (Mg) | mg/l | N.A. | <0.005 | |
| Acidity / alkalinity at 25 °C | pH | 5.5 | 7.5 | 7 |
| Hardness | mmol/l | <0.04 | 0 | |
| Bacteria | CFU/ml | <50 | 0 |
The physical and chemical quality stated above applies at the supplier’s truck loading station only.
1 ppm (part per million) = 1 mg/l. µS/cm = microsiemens per centimetre. The supplier’s buffer tanks for demineralised water are open to the atmosphere, so CO2 dissolves in the water and raises its conductivity. That is why conductivity is given both with and without the dissolved CO2 (degassed).
The water is produced by filtration, softening, reverse osmosis (RO) and mixed-bed ion exchange. It is not chlorinated, and any free chlorine in the raw feed water does not pass through the installation, so free and total chlorine are given as not applicable.