Static Electricity 2000 Edition

9.2.4.6 Ribbon Tacking.
On high-speed offset and gravure
presses, high-voltage tacking is used to improve the delivery of
signatures to the folder. These high-voltage devices should be
suitable for Class II, Division 2 locations if subject to accumu-
lations of settled paper dust.
9.2.5 Control of Static Electricity in Web Processes.
9.2.5.1
Higher operating speeds result in the potential for
increased volumes of flammable vapors in the immediate vicin-
ity of the area where flammable liquids are applied to the sub-
strate. Coating technology such as the enclosed ink gravure
fountain has minimized the volume of flammable vapors in the
application area. Solvent vapors can be diluted below the LFL
by means of mechanical ventilation. The performance of the
ventilation system is optimized by capturing vapors as close to
their source as possible. The ventilation system should be inter-
locked with the equipment to ensure safe operation of the pro-
cess. Vapors will always be within the flammable range in the
areas close to the application process and the substrate.
9.2.5.2
A common method of removing static electric charge
from processing machinery is by grounding the machine. All
conductive parts of the machine should be electrically bonded
together for this method to be effective. It should be noted
that the charge on the material being processed is not
removed by this grounding and bonding.
9.2.5.3
The ionization method of charge neutralization is the
most effective means for controlling static electric charge on
the webs in presses and coaters. Neutralizers, also called static
elimination bars or inductive ionizers, are commonly used
close to the substrate, but they should not touch the substrate.
The reduction of charge at any one point in the operation
does not prevent generation of charge in later steps of the pro-
cess. Static neutralizers might be necessary at a number of
locations (see Figure 9.2.5.3).

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SPECIFIC APPLICATIONS