“Static season” Is In Full Force In The Northern Hemisphere!
Nex Flow™combines its Silent X-stream Air Blade air knife and its Standard Air Blade air knife with an ionizing bar (also referred to as a static bar or anti-static bar) in order to remove static at a distance from a charged surface and also to clean charged surfaces of dirt and particulate.
You may have seen claims of some companies to remove static charge from 20 feet away utilizing static bars with air knives. The truth is, removing static charge depends on several factors – the size of the charge, the distance from the static bar and the strength of the static bar.
An air knife system may indeed remove a static charge from 20 feet away but it will take some time.
We have had to often replace equipment from companies making such claims on machines when the customer realizes that the system just doesn’t remove the charge for the limited exposure time it has to the static bar and air knife.
If fact, even a static bar “alone” can remove static charge from 20 feet away given enough time – but “time” is the key word here. On fast moving machines, available time can be in milliseconds.
The Silent X-Stream Air Blade Ionizer is quiet, efficient in air use and effective – can use either a standard strength static bar or extra strong static bar
Here is basically how AC static eliminators work with air knives. (There are DC type static eliminators as well but normally AC static eliminators are used with air knives). Static bars “ionize” the air utilizing a corona effect at the pins along the static bar. They create positive and negative “ions”.
The negative ions created cancel out the positive charge on a charged surface and the positive ions cancel out the negative charge on a charged surface. It takes time for the ions to migrate to the surface so the amount of “ions” and the “exposure time to the ions” is important. When an air knife is utilized it “pushes” the “ions” toward the charged surface.
As the ions are pushed, even with the laminar flow of the air knife, some ions recombine actually reducing the strength of the static bar the further the surface is away from the static bar. The laminar flow minimizes this ion recombination effect but it still happens. For fast moving webs, or sheet fed operations that can generate significant charges on material, an air knife with a regular static bar will rarely have the strength to remove static charge because the exposure time is not adequate.
In such cases and extra strong static bar can be used with an air knife to increase the amount of ions hitting the charged target to remove the static.
Nex Flow™ has such an extra strong static bar (the triple X) bar with produces significantly more ions than a normal static bar. In fact, the bar alone without an air knife will remove static at 4” or more from the target on applications such as at slitters where you cannot get close.
Combined with an air knife, this static bar can do the job at much greater distances in a reasonable amount of time where the traditional static bar fails and in fact eliminate the static on fast moving webs, or sheet fed operations with high static charge. It can even eliminate static charges at 20 feet away in a reasonable amount of time! Again, the key is phrase is “reasonable amount of time”.
As for cleaning a charged surface, the air knife and static bar combination is still an excellent solution – the single most common application for using an air knife and static bar combination. The higher the charge on the surface and the faster the speed, the stronger the static bar needs to be. For slower speeds a regular static bar and air knife combination is typically adequate.
HOW DO I KNOW ITS WORKING?
One of the key questions we get is “how do I know if the static bar is working?” AC testers (sometimes at inflated prices) have sometimes been promoted to check if static bars are working. However, these AC testers are misleading.
They only indicate if there is power going through the static bars. It does not indicate if they are working properly at all!
A static bar requires 3600 volts (at very low current of course) at the pins located on the static bar to generate the “corona” which creates the ions that do the job of removing static charge.
This voltage can be easily measured qualitatively with something like our Multicheck which indicates if there is adequate voltage at the pins.
(A light turns green if the voltage is adequate.) The voltage, if too low can be from a bad static bar, or power supply or may simply be dirty and cleaning can bring the voltage back up to normal.
The Multicheck is a low cost device to accurately indicate of a static bar is working.
The Low Cost Multicheck Provides a Qualitative Check to make sure the static bars and power supplies are working.
A static meter of course tests the real effectiveness of the static removal system and can pinpoint where the static charge is the highest and also indicates where the charge can come back once it is removed.
The Multicheck is a “must have” low cost device. A static meter is a more costly option depending on how critical the static charge can be to your operation, and it will give a quantitative assessment of your static problem and evaluate the effectiveness of your solution.
A Static Meter provides a Quantitative Assessment of the static problem and effectiveness of the solution.
Nex Flow™ has extensive experience in static control and can answer your questions and address applications realistically and honestly. Not every application needs an air knife with the static bar. But some applications can use a stronger static bar for a more effective solution.