Harsh environments

In certain industrial sectors or applications where air conditioners operate, aggressive and corrosive agents may be present, such as: chloride/sulphide compounds (coastal areas), sulphur oxides/nitrogen oxides (polluted industrial areas), airborne particles/cutting oils/solvents in factories, the presence of iron dust, ammonia, and sulphur oxide in the air. These substances can lead to various phenomena of corrosion or oxidation.

Among the main components subject to deterioration are the external carpentry, electrical components and the refrigeration circuit located on the condensing/external side of the unit.

The phenomenon of corrosion

Corrosion is the deterioration of a material due to chemical reactions initiated by substances present in the environment, which alter the state of the material itself.

In galvanic corrosion, deterioration occurs when two different metals come into contact with each other in the presence of an electrolyte, which can be moisture. An ion migration and therefore an electric current is created between the two metals, which causes corrosion in the metal with lesser electronegativity, called the anode.

Another type of corrosion is oxidation, or more correctly called redox: in a substance, there is a reduction of electrons, which therefore shows an increase in its oxidation state. Iron is one example, where rust formation is caused by prolonged exposure to air and humidity.

Finally, there is corrosion due to the attack of specific acidic substances present in the environment, such as hydrochloric or sulphurous acid.

An example: wastewater treatment

The municipal wastewater treatment service allows for the conversion of residual sludge into biogas for electricity generation. This site houses centrifugal extractors or pumping systems, which are paired and controlled by an electrical control panel. The latter is designed for controlling and distributing power, and managing process parameters. The equipment within it generates a considerable thermal load that needs to be dissipated and therefore conditioned. In this type of environment, certain substances such as ammonia, sulphur oxides, and hydrogen sulphide are present, making the atmosphere highly corrosive and causing deterioration of pipes and electrical components, significantly affecting parts containing copper or electrical contacts.

Industrial air conditioners for aggressive environments

With two special products, Protherm CVE0800220Z003 and CVE2000261Z000, Cosmotec offers an air-conditioning solution with enhanced corrosion resistance. These two air conditioners are therefore suitable for operation in highly demanding environments and provide a longer service life than standard air conditioners. This is made possible thanks to dedicated solutions protecting the structural frame, refrigeration circuit and electronic control elements — components most exposed to potential corrosive attack in certain environments containing chemically aggressive substances.

The printed circuit board of the electronic control unit, located on the evaporator/cabinet side, and the display, mounted on the panel, are coated with a protective resin layer that prevents substances or moisture from settling on the copper conductive tracks.

The panel, as part of the woodwork primarily exposed to the external environment, is made of stainless steel, which has properties of resistance against corrosion/oxidation phenomena.

The heat exchangers (condenser and evaporator), the largest components in the refrigeration circuit, are protected by a specific treatment depending on the type of component. Furthermore, the external part of the refrigeration circuit, both pipes and welds, are also covered with a treatment to increase protection against corrosive agents.

The air conditioners mentioned above are also available in versions with a painted sheet-metal enclosure (part numbers: CVE0800220Z004 and CVE2000261Z001) when protection of the enclosure structure is not required and only the components containing copper need to be protected.

A valid alternative, where water is available and can be used as the cooling medium, is the EXW Air-to-Water Heat Exchanger range, as no parts of the unit are exposed to the external environment. Air-to-water heat exchangers are also optionally available with a stainless-steel enclosure.