Page 33 - trends in automation 1.2013

A ny DIY enthusiast who has ever
tried painting with an aerosol
can will no doubt have expe­
rienced that overspray can occur
when you spray on paint. Or, to put it
another way, you miss the mark. The
overspray gets on clothing and floors and
is dispersed virtually invisibly in the air.
While on a small scale this may not pose
a major problem, it is important on the
scale at which industrial painting is carried
out. Using large exhaust air systems,
the overspray must be removed from the
paint booth and the extracted air re-
placed with fresh air. As it must not end
up in the environment, high-tech mem-
brane filter systems remove the mixture
of aerosols and paint particles from the
exhaust air. However, this process incurs
high costs in two areas – fresh air supply
and cleaning of the filters.
Cleaning without a break
The new RECLAIM system from Keller
Lufttechnik regenerates filter elements
during operation. It gives companies
in the coatings industry such as mks
Metallbau Schreiber GmbH, which recently
began using the RECLAIM system, a
major advantage by making downtime for
cleaning filters a thing of the past. This
is thanks to a clever system consisting
of automatic compressed air cleaning and
the new application of the pre-coating
material – an auxiliary filter layer. Lime-
stone powder is used for this purpose.
Sprayed onto the fabric filter material
coated with a PTFE layer, it absorbs the
overspray. Without the pre-coating
layer the filter would quickly clog up and
become unusable.
Multiple uses of the pre-coating
The limestone powder bonds with the
adhesive aerosols of the overspray
and can be used multiple times. Weight
sensors located under the dust silo
detect the degree of saturation of the
pre-coating material with overspray.
As long as a defined total weight, consist-
ing of pre-coating and powder, is not
exceeded, the mixture previously blown
off the filter plates can be blown back up
onto the filter plates.
The mixture of limestone powder and
paint overspray forms a new auxiliary
filter layer. When the limestone powder
becomes saturated with overspray, it is
automatically removed from the system
and new limestone powder is added.
Variable flow rate
The central point of control for this
sophisticated automation solution is the
valve terminal CPX-VTSA from Festo.
Whereas similar systems previously used
2/2-way individual valves without a
complex monitoring and control function,
the CPX-VTSA now guarantees a smooth
process. Keller Lufttechnik regulates
the flow rate of systems of various sizes
simply by choosing valves of different
sizes on the valve terminal. The individual
valves are precisely adjusted to the
required flow rate using pressure regulator
plates.
Too much of a good thing: The overspray produced
during spray painting must be extracted from the
paint booth.
Efficiently solved: The limestone powder bonds
with the aerosols of the overspray and can be
used several times.
1.2013 trends in automation
Synergies 32 – 33