United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-98/050 June 1998
Project Summary
Fugitive Emission Reductions
Due to the Use of Enclosed
Doctor Blade Systems in the
Flexographic and Rotogravure
Printing Industries
Mark A. Bahner, Dean R. Cornstubble, Keith E. Leese, and G. W. (Bill)
Deatherage
This project summary describes the
results of an evaluation project to quan-
tify the level of fugitive emission reduc-
tions resulting from use of enclosed
doctor blade (EDB) systems in place of
traditional ink feed systems at
flexographic and rotogravure printing
operations. An EDB system is an inno-
vative ink feed system that contains an
enclosed ink chamber. Such a system
has the potential of limiting fugitive
emissions from each printing station
on a printing press.
Traditional printing ink feed systems
employ ink pans; solvents in the ex-
posed pools of ink in these pans create
fugitive volatile organic compound
(VOC) emissions. EDB systems elimi-
nate these exposed pools of ink, and
can therefore reduce VOC emissions.
This project involved testing for fugitive
emissions at flexographic and rotogra-
vure printing stations, to quantify the
potential emission reductions achieved
by EDB ink feed systems. Prior to this
testing, the magnitude of the emission
reduction achieved by EDB systems
had not been quantified.
Testing was conducted on single-color
stations on flexographic and rotogra-
vure presses. Emission reductions
achieved by EDB systems were mea-
sured, and printing station operators
evaluated the quality of the printing with
traditional and EDB systems. Addition-
ally, evaporation rates from ink pools
were measured in a laboratory test.
The measured emission reductions
on the flexographic press ranged from
0.26 to 1.83kg/h with the press idle,
and 0.84 to 0.89 kg/h with the press
running. Measured emission reductions
for the rotogravure press ranged from
0.35 to 0.36 kg/h with the press idle,
and 0.83 kg/h with the press running.
These values were consistent with ink
pool evaporation rates measured in the
laboratory.
This Project Summary was developed
by EPA's National Risk Management Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
Previous cooperative research efforts
between Research Triangle Institute (RTI)
and the Environmental Protection Agency
(EPA) have identified traditional ink feed
systems as sources of emissions in
flexographic and rotogravure printing op-
erations. These ink feed systems are
therefore areas for pollution prevention
technology. Enclosed Doctor Blade (EDB)
systems, which eliminate several exposed
-------
ink surfaces found in traditional ink feed
systems, represent one potential pollu-
tion prevention technology.
EDB systems can be expected to re-
duce solvent usage during ink feed sys-
tem cleaning and reduce leftover ink at
the end of a print run. The potential for
EDB systems to reduce emissions during
printing is less certain. Some printers
maintain that these systems reduce ex-
posed ink surfaces such as the ink pan,
and therefore must reduce emissions.
These printers point to the fact that they
do not need to add as much make-up
solvent to the ink during print runs. Other
printers question this observation, and
believe that most fugitive emissions re-
sult from the ink exposed on the anilox
cylinder. These printers believe that any
reduction in fugitive emissions is prob-
ably negligible, since EDB systems are
similar to traditional systems in that ink
on the anilox cylinder is still exposed to
air.
The purpose of this testing was to mea-
sure volatile organic compound (VOC)
emissions from flexographic and rotogra-
vure presses operating with traditional and
EDB ink feed systems. Additionally, print-
ing quality was evaluated for the EDB
system on a rotogravure press, since
EDBs are not commonly used as ink de-
livery equipment in rotogravure printing.
Methods and Materials
Emission reductions achieved by EDB
systems were measured for a single-color
station on flexographic and rotogravure
presses. Temporary enclosures were con-
structed around the presses. Emissions
were first measured with the traditional
ink feed systems operating. Then emis-
sions were measured with EDB systems
installed, and the emission reductions
were calculated.
Emissions were determined by mea-
suring air flow rates and pollutant con-
centrations at all inlets to and outlets from
the enclosures. Air flow rates were mea-
sured by pitot tube (differential pressure)
or by hot-wire anemometer, depending
on the air velocities being measured. At
the flexographic printing facility, total hy-
drocarbon pollutant concentrations were
measured primarily with a portable flame
ionization detector (FID). At the rotogra-
vure facility, concentrations were mea-
sured primarily with a fixed-path-length
infrared spectrophotometer.
In addition to hydrocarbon emission
measurements, an attempt was made to
determine whether the enclosures that
were constructed had any influence on
the emissions from the traditional and
EDB ink feed systems. This assessment
was performed by simultaneously mea-
suring both hydrocarbon emissions and
capture efficiency of a tracer gas, at vary-
ing rates of enclosure exhaust (at the
flexographic facility) or containment (at
the rotogravure facility).
The tracer gas that was used to mea-
sure enclosure capture efficiency was
carbon dioxide (CO2). Enclosure capture
efficiency was evaluated by the ratio of
mass measurements of CO2 injection rate
and CO2 capture, as measured by CO2
concentration measurements.
After the emissions tests were per-
formed at the two printing facilities, ink
evaporation rates were measured in a
laboratory, to aid in understanding and
evaluating the field testing results. These
laboratory ink pan measurements involved
pouring press-ready inks from the two
facilities into small pans. The pans were
located on top of digital electronic scales,
underneath a laboratory hood. The mass
loss (evaporation) rate was monitored at
two levels of air flow over the ink pool
surface. The areal evaporation rates de-
termined during this laboratory testing
were then compared with the field emis-
sions testing results.
Results and Discussion
The measured emission reductions on
the flexographic press ranged from 0.26
to 1.83 kg/h with the press idle, and 0.84
to 0.89 kg/h with the press running. Mea-
sured emission reductions for the roto-
gravure press ranged from 0.35 to 0.36
kg/h with the press idle, and were 0.83
kg/h with the press running.
Laboratory ink pan evaporation tests
were performed with the flexographic and
rotogravure inks. These laboratory tests
can be combined with estimates of the
ink pool surface areas at each of the two
facilities, to produce predictions of the
emission reduction benefits of eliminat-
ing the ink pool surface areas at each
facility. The predicted emission reductions
range from 0.11 to 0.28 kg/h for the
flexographic press, and 0.18 to 1.12 kg/h
for the rotogravure press. The predictions
for the flexographic press are generally
lower than the measured results, while
all the rotogravure results fell within the
predicted range. It appears that labora-
tory ink pan measurements can be used
to provide order-of-magnitude predictions
for emission reductions achieved by EDB
systems.
Problems were experienced with the
CO2 tracer gas injection and resulting
enclosure capture efficiency measure-
ments. These problems prevented defini-
tive conclusions about the effects of the
enclosures on emissions from the tradi-
tional and EDB ink feed systems. How-
ever, the high enclosure exhaust rate used
on the flexographic system appeared to
artificially increase emissions; future re-
search on evaporative emissions within
enclosures should consider this possibil-
ity.
The EDB system used on the
flexographic press resulted in acceptable
printing quality. The EDB system used on
the rotogravure press resulted in unac-
ceptable printing quality, even when print-
ing line speed was slowed. However, it
may have been possible to improve the
printing quality of the rotogravure EDB
system, if production requirements had
not dictated a return to the original sys-
tem.
Conclusions
The EDB system is currently commer-
cially available for flexographic printing,
and reduces fugitive emissions. The EDB
system, as installed during the test for
rotogravure printing, also reduced fugi-
tive emissions. However, the EDB system
at the rotogravure facility substantially
degraded print quality, even at reduced
line speeds. The issue of printing quality
will need to be addressed before EDB
can become a viable option for the roto-
gravure printing industry.
-------
M. Bahner, D. Cornstubble, K. Lease, and G. Deatherage are with Research
Triangle Institute, Research Triangle Park, NC 27709.
Carlos M. Nunez is the EPA Project Officer (see below).
The complete report, entitled "Fugitive Emission Reductions Due to the Use of
Enclosed Doctor Blade Systems in the Flexographic and Rotogravure Printing
Industries," (Order No. PB98-137391; Cost: $36.00, subject to change) will be
available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
CenterforEnvironmental Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGES FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-98/050
------- |