Static, everyone loathes it except for those kids that like to run around shocking their friends. This phenomenon affects not only everyday life with things like frizzy hair and that annoying zap you get when someone touches you but also industry. But what is static and how is it generated?
Static is generated on the atomic level from the exchange of valance electrons on each surface. The energy produced from the friction causes those valance electrons to enter an excited state; when in this excited state they begin to jump back and forth from atom to atom. When this happens, the atoms begin to accumulate either a positive charge if the atom lost electrons or a negative charge if the atom gained electrons.
As the charge accumulates on the surface where the friction occurs if a ground source (i.e., a piece of metal or a person) comes in close proximity to the charged surface an arc is generated between the two surfaces transferring the build-up of electrons and returning the charged surfaces to a neutral state.
But how can these surfaces become charged in the first place?
The most common and well-known way is via friction. Friction generation is when two surfaces rub against each other causing the static to build up on the surfaces. The energy from the two objects being pushed together and rubbing up against each other causes the electrons within the atoms to enter an excited state. When these electrons are in this excited state the valence electrons will jump from atom to another atom; this causes one atom to become positively charged (lost the electron) and the other to become negatively charged (gained the electron). The harder the two surfaces are pushed together and the faster they are rubbed together the more static will be generated.
A second type of static generation is contact static build up, which is when a charge that is built up when two surfaces impact each other and then separate. Much like friction static generation, contact static build up generates the charge on the surfaces from the kinetic energy of the impact. The material of the two objects in question will determine how many electrons are transferred from surface to surface based on the properties of the atoms in the material (Electronegativity, Ionization Energy, and Electron Affinity).
The third type of static generation is detachment static build up. Detachment static build up once again relies on the kinetic energy and the properties of the atoms in the material. When the two surfaces are pulled apart the electrons that are transferring from one molecule to another get stuck with the molecules of one surface, which leaves both surfaces charged. This is seen a lot with plastic protective covers like the ones that come on a new window pane.
No matter how the static is generated EXAIR’s line of Static Eliminators including EXAIR’s New Intellistat that can neutralize a 1000V charge in under one second. Don’t let static cause issues for your production facility, contact EXAIR for a solution.
If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.