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Corrosion can affect integrated circuits, electronic circuit boards, control relays, transformers, motor control systems, control device systems and finally every type of electrical or electronic equipment. This corrosive effect develops mainly in certain parts which are particularly sensitive: terminals, contacts, IC connectors, windings and electrical systems.

The chemical filters can eliminate the corrosive air pollutants enabling the use of electrical and electronic equipment that complies with Directive 2002/95/EC (RoHS) of the European Union for reducing the use of hazardous materials in the manufacture of such equipment, as well as Directive 2002/96/EC (WEEE) on electrical and electronic waste.

The corrosion of metals in the atmosphere is due to chemical reactions that are caused by airborne chemical contaminants and the process speeds up with increasing temperature and humidity. As for electrical and electronic systems, erosion can be defined as the deterioration of the metallic substrate due to chemical reactions with its surroundings. More specifically, the effect of corrosive gases and water vapor (moisture) on the metal substrate, results in the creation and accumulation of various byproducts. As the chemical reactions continue, these byproducts may form insulating layers on the circuits, which in turn can lead to temperature failure or shorting. The continuing accumulation of by-products (salts) can cause either the detachment of the surface coating of gold (which is used to lower the resistance) or the extrusion of the salts, through the pores of the coating to the free surface. In both cases the result is to increase the electrical resistance at this point of the circuit.

In this way corrosion can cause interference, false signals, errors in information transmission, failures and outages.

Corrosion Assesment
Damage to electrical and electronic systems caused by corrosion directly affects production, product quality, plant safety and repair costs. Corrosion Classification Coupons, CCCs are used as part of the Corrosion Assessment service to determine the level of corrosivity of the air intake. Analyzing these coupons, the Purafil laboratory has the ability to determine the types and levels of corrosive gases in the air stream and can thus suggest the required form of filtration.

At a more automated stage, air quality analysers from the Purafil OnGuard series, ONGUARD help in real time to solve corrosion problems resulting from air pollutants, before the appearance of serious damage. The atmospheric corrosion detectors from the OnGuard series constantly measure the influence of corrosion in real time as well as the temperature and relative humidity. By using these values OnGuard devices calculate levels of corrosivity according to the relevant ISA 71.04-1985 standard. These detectors have the ability to connect to a Building Management System or similar system.

Protection against corrosion
In places where electrical panels are installed or where sensitive electronic material are found, Purafil ECUs (Electronic Cabinet Units) systems are widely used because of their low cost and high efficiency. Here the method of generating excessive pressure of air, free from corrosive gases, is applied within each electrical panel, electronic device or working area with electrical / electronic device.

Firstly, the suction of air from the environment is carried out. In the first stage of the process, particles are removed. Then the air passes through a stage of chemical filtering, in other words through chemical neutralizers (media).The neutralizing chemicals are placed in aerodynamically shaped canisters to ensure minimal pressure drop, ECUlong residence time of the corrosive air, high efficiency and easy maintenance and replacement. The retained / neutralized pollutants are many, such as chlorine, hydrogen chloride, hydrogen fluoride, ammonia, sulphur oxides, hydrogen sulphide, mercaptans, volatile organic compounds (VOCs) and nitrogen oxides etc.

The chemically filtered air passes through a final processing step of removing particles. These particles might be products (salts) of chemical neutralization. This step reinforces the high performance and reliability of the system. The treated air passes through the fan which conveys it to the inside of the electrical panel or space to be protected.

The ECU system has side doors for easy access to the interior and for changing the chemical and particle filters. The frame of the fan and the housing for the filters are made of aluminum, while the walls are made of galvanized sheet metal.

More problems exist especially in marine applications relating to the size and power supply of the systems (due to space limitations and non typical power supply characteristics), as well as to permanent environmental conditions (salt and ions from sea water) or intermittend ones (corrosive pollutants like mercaptans and hydrogen sulphide during loading / unloading of tankers, particulate pollutants in bulk carriers). For these reasons the recommended system type is F-GRID that is produced in the following types:

Contact

K. Karamanli & Iroon Polytechniou
P.O.Box 74, 19300
Aspropyrgos, Attica, Greece
Map coordinates: 38.060283 N, 23.580052 E

Phone 1: +30 210 53 25 404-5
Phone 2: +30 210 40 14 733
Fax : +30 210 53 22 544
E-mail: info@dimtech.gr