DI is an expression meaning "deionization". This term comes from the fact that the resin mixture in the tanks treats the water through the principle of deionization. The term mixture is used to define the resins inside the tank, as there are several different types. To name only the major types, cationic resins capture the positive ions present in the water (cations) while anionic resins capture the negative ions (anions). Mixed resin tanks therefore have the ability to exchange both anions and cations, resulting in the production of highly ionically pure water.
Briefly, deionization works by exchanging unwanted ions with other types of ions. Generally, cations will be exchanged for hydrogen (H+) while anions are exchanged for hydroxide (OH-). These two ions combined (H+ / OH-) form H2O, which is why the water coming out of a DI system is so ionically pure.
What are the characteristics of a deionization system (DI)
Les systèmes de déionisation peuvent se retrouver à bien des endroits dans un système de traitement d’eau. Typiquement, la section DI d’un système de production d’eau ultra pure consiste en un ou des réservoirs remplis de résine et d’indicateurs de qualité. La dimension des réservoirs varie en fonction du débit visé. En effet, plus le lit de médias (résine) est large, plus le débit sera élevé. Alors que les différences de diamètre du ou des réservoirs permettent d’ajuster le débit de filtration, le nombre de réservoirs et la quantité de résine permettent d’ajuster la qualité, la continuité et la redondance du traitement. En fonction de la qualité d’eau à traité, une plus grande quantité de résine permet l’échange d’une plus grande quantité de contaminants. D’ailleurs, plus il y a de résine, plus votre système peut fonctionner longtemps sans avoir besoin de régénération.
The quality indicators found on deionization systems are generally used to indicate whether or not the ion exchange is done properly. Although there are several other types of indicators, the most commonly used quality indicator is a resistivity meter. Calculating the resistivity of water indirectly tells you how many ions are in the water since pure water that is free of contaminating ions does not conduct electricity.
Essentially, to indicate if ion exchange is occurring properly, the quality indicator lights up green. When the ion exchange is not adequate, the quality indicator lights up red. There are obviously other types of quality indicators that can be more precise in their indications, but they are rarer and can sometimes be useless. To make a long story short, if we keep in mind the red/green indicators, when the red light comes on, the resin is exhausted and must be regenerated or changed.
What is the point of having multiple tanks in a DI system?
Les systèmes DI sont construits pour fournir de l’eau d’une qualité pré établie, et ce, de façon continue. C’est pourquoi on retrouve souvent deux réservoirs un à côté de l’autre. Le premier sert généralement pour retirer la majorité des ions indésirable alors que le deuxième agit en tant que polisseur afin d’assurer que la qualité du traitement soit constante.
Although the presence of two tanks ensures the consistency of operation and treatment of DI systems, quality indicators are the only way to know if the resin inside the tanks is exhausted or not. To ensure that processing can be done without interruption and to give operators time to perform the necessary steps, a quality indicator should always be installed between the first and second tank. This way, when the resin in the first tank runs out, the second tank continues the treatment and allows the operators to begin the process of changing the tanks.
It is common to see a quality indicator after the second tank in the DI system. Typically, when an indicator is installed at this location, it is much more accurate than the one at the first tank and can provide more information to help monitor the process more appropriately. In other words, the purpose of a second quality indicator is to monitor the effectiveness of the entire DI system, while the first is to identify when the resin needs to be changed.
When and how to change DI tanks
As mentioned above, DI tanks must be changed when the quality indicators turn red, or exceed the limits established for the water treatment in question.
To start the replacement of the DI tanks, it is important to empty the water inside them. There are two ways to do this. The first is to cut off the main water inlet to the system and let it drain. The second is to bypass the tanks if the piping and valves allow it. Once the tanks are drained, make sure the system is depressurized by opening a bleed valve. If your system does not have a bleed valve, you can always safely and quietly unscrew any connection on the system.
Once the water has been drained and the tanks depressurized, you can proceed by removing the main tank. Once this tank is removed, move the second tank, the one used for polishing the water, to the location of the first. This step is known as rotating the tanks. Since the resin in the polisher is in contact with far fewer contaminants, it does not exhaust as quickly, so rotating the tanks will make your system more efficient.
Once the main tank is reinstalled, install the tank with the regenerated resin as the polisher. Now that they are both installed, make sure that all connections are properly installed and before you start filling the system with water, make sure that the air in the system can be evacuated.
Conclusion
The abbreviation DI,
meaning deionization, refers to ion exchangers used for water treatment. As you
may have noticed, we have focused on the quality indicators as these are
essential to the proper functioning of a deionization system as they allow the
user to know when the resin needs to be changed or regenerated.
It is important to note that the terms " resin
change " vs. " resin regeneration " are very different and one
of them can save you a lot of money while promoting the respect of the
environment. To learn more
about the principle of regeneration, visit this page:
Bref, si vous avez des questions, commentaires ou besoins d’assistance en lien avec vos systèmes DI, n’hésitez pas à nous appeler, à nous écrire ou à nous laisser un commentaire ci-bas..