A very simple element that can avoid serious health hazards for operators and frequent maintenance activities.
In many industrial plants, the installed fans are at high risk of breakage or, at least, jeopardized by frequent failures. But on top of, they subtly imply serious risks for workers’ health and safety.
Without anyone being able to notice it, in fact, not negligible quantities of substances can come out of these machines, potentially flammable, toxic or polluting.
The presence of these substances, within the flue gases transported through the fans, is very common in industrial plants, indeed. Furthermore, many times it happens that these fluids are being distributed at elevated temperatures, across the entire the plant.
However, if the system integrator, supplier of the packages relevant to a specific plant, it reveals to be more sensitive to costs than to safety, very likely it will end up installing standard fans, simply selected out of a catalogue. This kind of piece of equipment, being designed to optimize costs, represent a simple choice when you need to manage just fresh air. The manufacturing choices behind those, lead towards light construction, poorly or not welded at all, thus allowing the gas to pass from the inside to the outside of the fan casing.

Furthermore, those kinds of fans are usually being delivered in the field without a critical component, which instead should be a minimum basic requirement when dealing with high temperatures fluids and / or containing dangerous gases or dusts. This component, which goes by the name of shaft passage seal, implements a barrier that can avoid contamination of the external environment with “toxic” fumes passing through the fan.
In this way, you can avoid by principle the risk of workers inhaling these dangerous substances and experiencing illness, intoxication and even consequent serious illness.
Additionally, this precious element prevents hot, acid or dusty fumes from hitting the fan bearings, damaging them and causing advance breakings, or at lease shortening of their predicted standard lifecycle. It seems to be a paradox, but just even a simple sealing, few hundred euros cost, can avoid severe production interrupts, and forced bearings replacement every 3-4 months.
It must be said that the sealing system needs to be carefully selected and sized, with a dedicated engineering calculation, which properly considers operating conditions and the kind of fluid to be managed. There are different types of sealing systems: you can start from the cheapest entry level one, made by one or more discs, basically composed by gasket- like material; going up to complex (and surely more expensive) mechanical seals, pressurized with a barrier gas, which is often an inert gas like nitrogen.

Finally, you must consider that without a seal, up around the 10% of the total fan gas flow rate can escape from the casing. Which means, the same amount of the absorbed power as well. Then you easily understand that the modest investment necessary to install this component can be pay-backed in few weeks of operation, even if the process fluid is simply clean air. The advantage and risk avoided are dramatically higher when you deal with harmful substances to be managed!

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