This week at DJES we had another wonderful opportunity to work with our customers doing staff training. One of the more interesting questions that was posed was - is water quality that important when doing laser water changes? The short answer is ABSOLUTELY! Industrial and water cooled YAG lasers for laser welding require deionised water with a specific conductivity which is checked at the time of the water change. What is the difference between distilled, demineralised and deionised water? Keeping it short and simple without a chemistry class, distilled water is boiled. Bacteria and viruses are killed and the steam from the boiling process is condensed and collected. This leaves salts and other non-volatile contaminants behind in the boilig container when the steam is condensed and the water vapour droplets are collected into a clean container. Some volatiles may be collected in this process but are of minimal concern in the amounts collected. Deionised water can go through one of several different processing methods, but are basically passed through charged resin filters which attract and remove ions in the water, and may also attract some, but not all, of the bacteria that may be present in the water. The outcome is basically water that has a low conductivity, that may still contain some bacteria and viruses. Demineralised water is processed to remove minerals, but some ions, bacteria, viruses, volatiles and other contaminants can remain.
The important point is that the water used is very high purity and has low conductivity. Any water process that leaves ions behind will not produce water of the quality required in your laser system as ions are conductive. Manufacturers will always clearly indicate which type of water is to be used in your laser system and if additional water treatments are required.
Some maintenance tips for water changes: