Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 79)

APNE-0016 78
Hints For Maximum Static Control And Effective Monitoring
High-speed operations might require a second static neutralizer along the web between some rollers
to sufficiently reduce the web charge.
For web materials thinner than 50mil, one ionizer and fieldmeter should be able to neutralize and
measure both sides of web. For web materials thicker than 50mil, an ionizer and fieldmeter may be
needed for both sides of web. The only way to know for sure is to install an ionizer on one side of the
web, and then measure the residual field on both sides of the web. If the non-ionized side exhibits a
higher field than the ionized side, then both sides require neutralization, measurement, and control.
If all proper spacing requirements can be met for web materials thinner than 50mils, the fieldmeter
probes should be mounted with the measurement aperture facing downward. This is necessary to
minimize foreign material entering the sensitive probe aperture.
For optimal performance, static eliminators need to be positioned using fieldmeters to obtain the
lowest readings, both for distance from the web as well as distance from the previous roller. This can
best be done using permanently installed fieldmeter probes after the eliminators.
Determining Locations For Continuous Static Monitoring In Hazardous (Flammable)
Areas
As described in the section of this document Machine Grounding Hazard Elimination above, the most
critical static control item to implement is effective grounding and bonding of conductive machine
parts. Make sure conductive machine part shapes cannot also contribute to the static hazard
problem by observing the recommendations in the section of this document, Machine Part Geometry
Hazard Elimination. Then locate the general machine static monitoring positions as described in the
section of this document Determining Locations For Continuous Static Control And Monitoring In
Nonhazardous Araes Using Portable Fieldmeters.
Last, but most important, particular attention must be focused on the hazardous operations
themselves. In a web converting process, these are usually flammable, solvent-based printing and
other gravure operations, or coating, impregnating, and spreading operations. Charge neutralization
devices should be installed after the web roller just prior to the hazardous operation roller. Additional
devices should also be installed after the hazardous operation roller, and after each drying and
turning roller in the hazardous rated area [3]. The devices installed in hazardous locations need to be
rated Intrinsically Safe for the atmosphere in which they are placed.
Permanent fieldmeters should then be installed after each charge neutralization device to monitor its
performance and indicate when maintenance on it is required.
Permanent fieldmeters are especially necessary in hazardous areas to verify that nonhazardous web
surface charge density levels are maintained. The probes are installed downstream of passive or
active ionizers to ensure that the ionizers are operating correctly. This scenario assumes that all
rollers but gravure and impression to be outside the classified area. All electrically powered
equipment installed in these classified locations must be approved for the solvent atmosphere in
which they are located, so both the fieldmeter probes and the ionizers must be approved for the
classified areas in which they are installed.
In hazardous locations, it is recommended that backup fieldmeters be installed, in case the primary
fieldmeter at that position fails. Typically, one probe is located about one-third of the way across the
web, and the other probe is located about two-thirds of the way across the web, attached to the
same mounting bracket.
Continuous Monitoring Of Fields In High-Risk Machine/Product Performance Areas.
Permanent Fieldmeter System. The Monroe Electronics Model 177A Static Monitor is a four-channel
electrostatic fieldmeter. The Model 177A is the only system designed for long-term unattended
monitoring of static levels in industrial environments. The Model 177A accepts up to four Model
1036E or Model1036F electric-field-sensing probes. The probes measure the electric field in the
particular locations where they are installed, and they continuously monitor for electric field levels
that may indicate safety hazards or quality concerns. The probes can be mounted up to 1000 feet
from the Model 177A. Probes should be air purged for long-term stability.
Choice of locations for the probes is critical. Locations should be chosen based on an understanding
of machine/process performance. Handheld fieldmeters are used to help characterize the machine
and select locations (see APNE-0015 Electric Fields and Fieldmeters In Web Converting).