DI and RO - 2 methods of pure water production
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> Deionisation (DI) and Reverse Osmosis (RO)
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Deionisation (DI) and reverse osmosis (RO) describe two methods of producing pure water. clean Magazine reveals exactly how they do it.
Pure water is tap water which has had all minerals removed by a special filtering process. This process is called demineralisation. Foreign particles in water are not visible to the naked eye. They only become visible when the water dries after cleaning - when ugly traces of limescale and streaks appear on the glass.
There are two popular methods of demineralisation among professional glass and building cleaners: deionisation (DI) and reverse osmosis (RO).
The DI process: using resin as the key to pure water.
The DI process uses specially manufactured ion-exchange resins to remove dissolved minerals from the water, including cations such as sodium, calcium, iron and copper, and anions such as chloride and sulphate. The most effective systems, for example the UNGER HydroPower DI use a dispersal system to allow the water to flow through the resin. This activates the ion-exchange process: the minerals bind to the resin and are retained. Deionisation does not require any power; water pressure of around 2.5 bar is usually sufficient. One factor which must be borne in mind is regular replacement of the resin. After a time, it becomes saturated with retained minerals, and loses its effect. UNGER offer products such as the QuickChange resin bag for the HydroPower DI Filter. These are conveniently pre-filled with resin; replacing them is clean, easy, and done in just a few seconds.
The RO process: producing pure water using high pressure.
In modern reverse osmosis (RO) systems, tapwater is demineralised using a 3-step process; for example, using the UNGER HydroPower RO. First, the water passes through a carbon pre-filter which removes chlorine and sediment. It is then pumped under pressure through two high-performance RO membranes, which retain up to 98 percent of dissolved minerals and impurities.
At this point the flow of water is separated into waste water on one side and pure water on the other. Finally, it flows into a DI filter, where any residual minerals are removed by a premium ion-exchange resin. The result: 100 percent pure water.
Please note: RO systems are recommended for use with hard or very hard water, in situations where there is a constant water flow and high water consumption. If the damp membrane remains in place too long, it becomes blocked, reducing its efficiency and possibly damaging it. Regular maintenance and regular rinsing with water are very important. An intelligent assistance system is a practical solution, for example, the RO Smartguard. This monitors the efficiency of the filter system during operation, and provides alerts when pure water quality is diminished. The condition and performance status of all filter components are indicated on a display. A traffic light indicator provides information on when the filter cartridges need to be replaced, leaving you to concentrate on the most important thing: doing a good job.
Using pure water: Here's how to do it!
If you are a window- or building cleaner with little experience of pure water systems, it's easy to make mistakes when using them. The result: smears or other unsightly deposits on the window surface. For the most common problems when using pure water, and how to avoid them, click here.
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