Page 3 - INDEX Winter 2024

SPONSORS – IWTM,

WATER BY DE SIGN

The alternative to filling a system with raw water and then adding chemicals to it in order to prevent the occurrence of
corrosion is to fill the system with conductivity, bacteria and pH controlled demineralised water, and then to maintain
the system in this non-corrosive state. This is the approach promoted in VDI 2035.

IWTM’s ProFill range demineralises raw fill water to no or low conductivity with a control on the pH, either at
initial fill or for circuit top-up while the system is operational. The approach used by IWTM passes the
water through an excess anion mixed bed resin. This technique for water treatment replaces cations in untreated water
(e.g., Na+, Ca++, Al+++) with a cation on the resin (H+) and the anions in untreated water (e.g., Cl-, NO3-, SO4--) with an
anion (OH-) on the resin. This effectively removes all the salts and minerals dissolved in the waterwater. In addition, the
resin has a surplus of anions (OH-) to remove the free, dissolved carbon dioxide, which in turn controls the pH of the
treated water. This is further enhanced as IWTMs resin has excess anions (hydroxil ions) which assist with this control
of the pH.

Various water treatment specialists use
different types of resins depending on
the requirement; all demineralisation
resins have hydrogen and hydroxy ions,
which get exchanged with the salts and minerals
present in the untreated water when the treatment
process commences.

Once a system has been filled with demineralised
water, its quality is maintained by circulating the system water through a Protector unit fitted with high purity magnesium
anodes. To comply with VDI 2035, the water in a closed loop system must be sightly alkaline with a pH value of between
8.2 and 10 and it must have very low conductivity and very low dissolved oxygen.
Critical to electrochemistry and the function of the Protector is the sacrificial magnesium anode, which will corrode
as it scavenges oxygen from the water in the system. This galvanic process removes dissolved oxygen from the water
and releases magnesium hydroxide, an organic compound often used in antacids as an alkaline pH buffer to help
relieve indigestion. In a closed loop system, the magnesium hydroxide helps increase the pH of the water, turning it
alkaline, and settling within the range set by VDI2035. The result is a system with an optimum pH with minimum oxygen
concentration where corrosion damage is unlikely to occur. The anode will need to be replaced on average every three
years as part of the maintenance regime.

Magnesium anode electrochemistry can also be a very effective way of controlling bacteria. The controlled pH, low
oxygen, low conductivity and the lack of debris, chemicals and biofilms remove the environmental conditions that
allow bacteria to flourish.

Whilst systems with aluminium components are recommended to operate at a more controlled pH level of 8.2 - 9 the
Protector still operates effectively to safeguard these components if the pH increases beyond those levels. This is
achieved by ensuring dissolved oxygen and conductivity are controlled to a level where the slightly elevated pH, in and
of itself, is not sufficient to effect the reactions that cause corrosion.
In addition to new heating and cooling systems magnesium anode electrochemistry can also be applied to existing
systems, or to rectify a system where chemical water treatment has proved ineffective. When used to restore an existing
system the Protector's vortex separator enables corrosion residues carried along by the flow of water to be collected in
the unit’s reservoir ready for blown down, until the water runs clear.

The Protector also incorporates a magnetic filter to remove entrained ferromagnetic material, such as iron oxides and
magnetite, which can clog up circuits and heat exchangers triggering localised corrosion where it collects as sludge.
The magnet is located outside the device so that it can be retracted to release the particles for removal through the
sludge drain.

To remove micro gas bubbles, the Protector also incorporates an automatic air vent. Gases in a closed-loop system
dissolve in colder water but are later released as tiny bubbles when the water heats up, or its pressure decreases.