Basic concept of Demi water used in industrial application and equipment
Water without minerals such as, salt etc. called de-mineralized water or demi water or de-ionized water. With low mineral content, demi water has some changed expected properties such low conductivity, low corrosive effects etc. Demi water has some specific uses in industrial applications such as, boiler, pipeline etc.
Regular water with mineral contents has some corrosive effects to metals or conductivity issues for certain applications. Additionally, minerals deposits or residues might settle in the metal surface, which in time become hard. This is called Scaling effects.
Demi water is used extensively for all mos all of the industrial applications in which there are water use provisions. Without demi water, the expensive parts of would be of shorten life time with simple water.
Demi water quality and
specification varies as per the use. Usually the manufacturer of the equipment
dictates specification of the demi water in which it is going to be used. Even
the equipment manufacturer itself provides some time provided the demi water
system.
There is a international standard- American Society for Testing and Materials
(ASTM) D1193-91, Standard specification for Reagent Grade Water
ion exchanger resin beads used for demi water preparation
Demi water is prepared through ion exchange resin. These are
special types of insoluble matrix (or support structure) normally in the form
of small (0.5-1 mm diameter) beads, fabricated from an organic polymer
substrate.
What ion exchange polymer does is just trap certain ions in exchange of
releasing of other ions. In
case of basic demi water preparation, ion exchange resin releases hydrogen,
hydroxide, and traps minerals ions. For specific
application and usages, the ion exchange process may vary with additional
steps.