Humidification is a very effective way to eliminate the build-up of static electricity in manufacturing environments. By keeping the humidity at 55%RH the moisture content of the air is a natural conductor and earths any potential static charge.
Static build-up in manufacturing environments often causes a reduction in productivity, a drop in product quality, safety issues with uncontrolled sparks, and physical damage to equipment, especially electronics and PCBs.
These static problems are particularly prevalent in industries like packaging, printing, paper, plastics, textiles, electronics, automotive manufacturing and pharmaceuticals.
In order for friction to produce a static charge the air must be below 45%RH. Between 45-55%RH static will still build-up but at a reduced level as it leaks to ground through the moisture content of the air. Keeping the air at above 55%RH ensures static never builds-up.
For large environments like printing halls or manufacturing lines, direct room humidifiers present an effective and economical solution. Atomising nozzles are mounted in the ceiling space and release a fine spray which raises the humidity to the required level.
However, industrial machines that generate heat can encourage static by creating their own dry micro-climates. Heat dries the air so a room with an overall humidity of 60%RH at 18°C may have localised dry air pockets by hot machines of less than 45%RH. If this machine also produces the friction required for static build-up, then there is a potential risk of static problems.
Where this is the case, localised spray systems can be employed to raise the humidity in the local area. Individual nozzles located directly on machines can ensure temperature gains don’t encourage dry air and therefore static build-up.
A relative humidity of above 40%RH will help to reduce problems associated with static build-up and subsequent electrostatic discharge (sparks).
Increased air moisture content allows dissippation of electrical charge through the air. Moisture in the air conducts electricity and allows it to flow away, reducing the possibilty of build-up in materials as a result of friction.
Siemens Gamesa, UK
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