24V DC Cooling Fan cover rust?

1, "24V DC Cooling Fan" accumulating the surface of stainless steel shroud attachments contain other metal elements or heterogeneous metal dust particles, in the humid air, condensate and stainless steel fixtures between the two together into a micro battery, causing the electrochemical reaction, the protective film is damaged, call it that electrochemical corrosion.
2, "24V DC Cooling Fan" cover stainless steel surface adhesion of organic juice (such as vegetables, soup, sputum, etc.), in the case of water oxygen to form organic acids, organic acids for a long time the corrosion of metal surfaces.
3, stainless steel surface adhesion containing acid, alkali, salts (such as wall decoration alkaline, lime splash), causing localized corrosion.
4, "24V DC Cooling Fan" cover in air pollution (such as with a lot of sulfide, carbon monoxide, nitrogen oxide atmosphere), the case of condensation of water to form sulfuric acid, nitric acid, acetic acid solution point, causing chemical corrosion. Above may damage the stainless steel surface protection film caused corrosion.