Designing Fans For Use In Corrosive Conditions

Further, for achieving optimal performance and increasing the longevity of the equipment it is essential to select the right fan for use in corrosive environments. The chance of erosion of the process fans depends on the industrial application of the fan. There are chances of corrosion in chemical, pulp and paper, or water treatment application, metal and mineral processing, petrochemical, pharmaceutical and steel processing industries.

Corrosive gases that exist in an industrial environment are hydrogen sulphide, chlorine, sulphur dioxide, ammonia, ozone, mercaptans, hydrogen fluoride or sodium hypochlorite. These are not gases that need to be dealt with, but these cause equipment corrosion.

The service life of fan constructed of carbon steel may be significantly reduced when corrosives are allowed to attack the surface of the metal through chemical or electrochemical action. Hence, it is necessary to provide protection from a variety of corrosives including acids, alkalis, solvents, salts, and oils. Some methods for inhibiting this corrosive action is by use of specialized alloys and fiberglass-reinforced plastic (FRP).

Remarkable resistance to corrosion is offered through stainless steel. But there are environments that can cause permanent breakdown of the protective chromium oxide passive layer on the steel, leading to corrosion on an unprotected surface. To improve resistance to corrosion resistance fans are manufactured using high-performance stainless steels which are steel alloys created by adding elements like molybdenum and nitrogen.  Stainless steel is more corrosion resistant as compared to carbon steel or mild steel.

Polyvinyl chloride (PVC) fans provide good protection from corrosion. PVC fans are suitable for up to 140°F. When compared with fiberglass-reinforced plastic (FRP) fans, PVC/ polypropylene fans often are more economical.

Polypropylene fans are resistant to many acids, caustic, and inorganic saline products used in labs and hence they are corrosion resistive. Further, polypropylene fans can be operated at higher temperatures than PVC fans i.e. up to 190°F.

For corrosion resistance, one can use fans made up of fiberglass. Other than corrosion resistance fiberglass also provides other applications such as fume, pollution, odor, process control, oil mist emissions, heating or cooling and scrubbers. Some advantages of using fiberglass fans are it provides superior corrosion resistance to gases and vapors.  Also, its maintenance costs are much lower and fiberglass fans are more economical than stainless steel construction.

Apart from building industrial fans with different materials, there are corrosion resistant coatings that can be applied for fans manufactured with regular materials. These protective coatings act as a barrier between the corrosive and the parent material. Protective coating selection is critical in determining the service life of the equipment. The actual chemical composition of the gas stream and concentrations and temperatures of the chemicals present must be considered for the selection process. There are nearly a dozen different types of protective coatings that can be applied to an industrial fan including phenolic, epoxy, Epoxy-phenolic, inorganic zinc, vinyl, coal tar epoxy, alkyds, silicone, polyurethane, polyester and vinyl ester.

The ambient air within the area of using corrosive material will also have a concentration of these materials. Therefore, it is important to consider this fact when choosing the correct fan for your industrial application.

Reitz India Industrial Centrifugal fans are custom designed to serve the needs of various processes in industries like cement, iron & steel, power plants, fertilizers/ chemicals and more. As a top quality ID Fan manufacturers , Reitz India has set a benchmark in delivering superior fans with high quality features and better industrial standards.