EXAIR published a white paper, Basics of Static Electricity, explaining what causes static electricity; how it is generated; and steps to eliminate it. You can get this paper HERE and start removing static issues from within your plant or process.
In this blog, I would like to expand on the subject of how static can be generated. On a molecular scale, the outer electrons that are orbiting the nucleus of an atom or molecule can be “stripped” and redistributed from one atom to another. This will cause an electrical charge imbalance called static. An additional electron will create negatively charged static, while atoms losing an electron will create positively charged static. With non-conductive materials like plastic, paper, rubber, glass, etc., the electrons cannot move back to the original atom. There are three common methods of static generation that will cause this phenomenon to occur. I will explain each one in brief detail below:
Contact: Whenever objects hit each other, electrons can be passed to or received from the surface of another object. The number of electrons being transferred is based on the type of triboelectric material. But, with plastic bottles or trays bumping into each other on conveyor belts, static can be generated relatively easily.
Detachment: When one material is separated from another by peeling, electrons may not be able to return to the original molecule. Because of their larger surface areas, adhesive tape and protective films are common for generating static charges by detaching. As an example; when the backing material is being removed from labels, the static will cause the labels to be misaligned or cause jams.
Frictional: This is one of the most common reasons for generating large static forces. It is caused by two non-conductive surfaces being rubbed together. The amount of force being applied to the material as it slides back and forth will create higher static charges. As an example, it is noticed when you rub a balloon on your hair. The more times that you rub the balloon against your hair, the stronger the static forces, allowing the balloon to “stick” to the wall. It is also noticed as sheets of material are stacked or run over rollers.
Static tends to propagate. The more contact, detachment, and friction that occurs, the higher the static charge. Even after the static charge is removed from the surface, it can regenerate using the same mechanisms described above. So, controlling the static can be determined by the type of treatment as well as the location for removal.
Another variable that affects static generation is humidity. Most process problems are noticed during the winter months as the ambient air is drier. With a lower relative humidity, static electricity can develop easier and with greater strength. We always refer to winter as “static season.” You may even notice this when you walk across the carpet and get zapped by touching a door handle.
EXAIR manufactures a large line of Gen4 Static Eliminators to remove this static nuisance. From now until March 31st, 2024, EXAIR will be giving away a free AC Sensor, a $76.00 value, as a promotional item with a qualified purchase of the Gen4 Static Eliminators. If you would like to discuss your application and potential static issues, you can contact an Application Engineer at EXAIR. We will be happy to help.
John Ball
International Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb