Twin City Protective Coatings Guide - ES-35 - Manual

The application of special finishes for the prevention of
corrosion, abrasion, and erosion has been the subject
of study in the air handling industry for quite some time.
As might be expected, some materials or finishes are
more resistant to corrosion than others, but no finish or
coating is completely immune from corrosion in all
respects. Therefore, corrosion resistance is of degree
only, based upon the choice of material made for any
particular problem. The data published in this bulletin is
based on the recommendations and claims put forward
by the manufacturers of such paints or coatings. While
we cannot be responsible for the accuracy of this data,
it should serve as a useful guide in selecting special
paints and/or coatings for handling corrosive atmo-
spheres. Twin City Fan & Blower does not, however,
assume any liability for the effectiveness of these coat-
ings, since they are rated in accordance with their
manufacturers’ claims only.
The rate of corrosion on any application depends to
a large extent on the concentrations of fumes, their
temperature, and the extent of moisture associated with
them. These parameters make it extremely difficult to
define corrosion resistance of any one coating by a
single rating as shown by a letter in our guide. Plant
engineers, with their experience on specific applications,
are in a better position to suggest the best coating for
their requirements. We suggest you refer to them when
possible for such advice.
Some restrictions on fans to be coated are deserving
of mention. Naturally, bearings cannot be placed in the
airstream. The use of variable intake vanes and outlet
dampers is not recommended, since it is almost impos-
sible to properly protect some of their component parts
such as linkages, bearings, etc. Shaft seals of a variety
of types are available and should be used. Special
types of seals may be required in some instances; refer
to factory. Drains, especially in handling moist atmo-
spheres, are a necessity. With these points in mind, the
corrosion resisting paint or finish can be applied either
to the complete airstream of the fan, or to the entire
fan, both inside and out.
Coatings and Their Characteristics
For all special paints or coatings and their applications
with variation in fan design, construction, and metal
preparation, AMCA recommended practice No. 2601-66
is carefully followed. For special paints, fans are phos-
phatized and washed followed by a prime coat and one
or more finish coats depending upon the application
and its requirement. In some cases, and as indicated,
sandblasting of the parts to be coated is necessary,
followed by the necessary coats of corrosive finish to
the thickness specified in the chart.
©2010 Twin City Fan Companies, Ltd.
ES-35
February 2010
Protective Coatings
& Paints Guide