Operation; Maintenance - Desco EMIT C/E Series Owner's Manual

distinctive blue light. This makes it
readily apparent that the ionizer has
its settings locked, preventing
unauthorized adjustment.
• AIRFLOW - this display indicates
relative airflow output from the fans.
If the key switch is in the "SET"
position and the "+" or "-" button are
pressed and held, the fan speed will
increase or decrease with a
corresponding change in the
AIRFLOW display. As fan speed is
increased, the display will move to
the right.
• MINOR ADJUSTMENTS
ACCESS - each fan zone may be
balanced separately. The adjustments
are designed for minor corrections to
balance one fan to another. Overall
balance adjustments should be done
with the "BAL" switches on the end
panel.
• VR6, VR5, VR2, and VR1 - are
the zone balance adjustments for the
zones 1 through 4 respectively.
Zone 1 is closest to the right end.
24" models will only have VR6 and
VR5 adjustments. These adjustments
are covered in the section titled
"Calibration Instructions".
• VR3 and VR4 - are adjustments to
center the alarm and to change the
alarm sensitivity. These adjustments
are covered in the section titled
"Calibration Instructions".
• ALARM SWITCH - this switch
provides an audible alarm to
supplement the flashing red PWR
light when the unit needs cleaning.

Operation

After the unit is mounted securely
and connected to a properly wired
outlet, turn the key switch to the set
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position. The performance of the
ionizer is directly related to the
airflow on the area to be protected.
Generally, try to use the highest
setting possible without disturbing
the operator or the work in process.
After allowing the unit to run for
several minutes, a charged plate
analyzer can be used to check the
balance and performance. We
recommend doing this at the time of
the initial installation, so that data
can be collected and saved for future
reference. Place the charged plate
analyzer directly under each fan and
record the float (balance) voltage. If
all fans are offset slightly in the
same direction, the "+" or "-" BAL
buttons can be used to correct the
offset. If the balance varies from a
positive offset to a negative offset
between fans, the individual fan zone
controls can be touched up slightly
as required.
It is not uncommon to find
differences between ionizers from
bench to bench or even between fans
on ionizers during initial setup. This
is often caused by the presence of
objects on or around the bench.
Large metal objects nearby or
machines or equipment on the bench
will often cause a shift in the offset
voltage at that area. The individual
zone controls of the C/E ionizers
allow this to be compensated for
during initial setup.
After balance offsets have been
checked, the decay performance of
each fan should be measured and
recorded. This information will be
useful to establish a maintenance
schedule. When decay times begin to
increase significantly, or if the red
PWR light begins to flash, emitter
cleaning is usually indicated. By
recording the time intervals between
the first few cleanings, a
maintenance schedule can be
developed. After initial setup and
testing has been done, the key switch
can be set to the LOCK position and
normal workstation use resumed.
If the ionizer is used in a manner
not specified by the manufacturer,
the protection provided by the
ionizer may be impaired.

Maintenance

"As with all ionizers, periodic
maintenance will be needed to
provide optimum performance."
(Reference: IEC 61340-5-2:1
paragraph 5.2.9).
The frequency of monitoring ionizers
really depends on how and where
they are used. Since the majority of
them use a fan to transport the ions
to the working area, the cleanliness
of the air directly affects their
performance over time and how
often the emitters should be cleaned.
EIA-625 recommends checking
ionizers every 6 months, but this
may not be suitable for many
programs particularly since an out-
of-balance may exist for months
before it is checked again.
ANSI/ESD S20.20 paragraph 6.1.3.1
Compliance Verification Plan
Requirement states: "Test equipment
shall be selected to make
measurements of appropriate
properties of the technical
requirements that are incorporated
into the ESD program plan." And
paragraph 6.1.3.2. Compliance
Verification Plan Guidance states:
"In addition to internal audits,
external audits (Organization and
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Employee Owned