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.
Silent
X-Stream™ Air-Blade™ Air Knife
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's 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.
Low
Cost Multicheck Provides a Qualitative Check
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.
Static
Meter Provides A Quantitative Assessment Of The Static Problem
And Effectiveness Of She 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.
