Cartridges or cyclones can use the same type of booth
canopy. The booth canopy should be sturdy, easy to clean
and maintain. Reasons for the booth canopy are:
? Powder containment.
? Enhanced transfer efficiency.
? Color change.
Powder is applied with an electrostatic charge, and the
objective is to obtain a high, first-pass transfer efficiency.
We want the powder attracted to the parts and not to the
booth canopy. The canopy design is an important factor
to the total integration of a powder coating system. The
four most popular booth canopies are polypropylene,
stainless steel, a combination of polypropylene and
stainless steel, and painted steel.
The most common canopy is the rigid polypropylene. It
was first introduced in the early 80s and has grown to
become the preferred canopy design. The polypropylene
canopy has a translucency that improves visibility inside
the booth and enhances gun transfer efficiency. It has a
long wearing, smooth, slick surface that is easy to clean
and does not attract powder or static build up. This is the
most expensive booth material available.
The second canopy design is made out of stainless steel
and is durable and solid. Although not as easy to clean as
a polypropylene booth, it is less expensive.
A third canopy design is comprised of a combination of
polypropylene and stainless steel. The polypropylene
panels are located around the gun slots and the roof in the
booth. Again, it is an economical option.
Lastly, the fourth canopy design is made of painted
steel.The painted steel canopy is actually the earliest
design, but after a few years and many color changes, it
looses its appearance. It is durable and solid but not as
easy to clean as the polypropylene or stainless steel
Booth air flow and gun placement are critical factors in
how well the booth will perform. In a powder coating
system, “more is not better.” Air flow must contain the
powder and not allow it to migrate through the opening.
At the same time, however, the powder must reach the
part. Optimal air flow will enhance the coating transfer
efficiency. The powder coating gun should be positioned
completely within the spray booth. What this means, is
the grounded booth wall, whether it's conductive or nonconductive
material, will be far enough from the
electrostatically charged tip of the gun to eliminate any
disturbances. Furthermore, booth walls and floors should
be smooth and free of joints. When it’s time to change
color, the entire inside of the booth will need wiping down
to remove excess powder. It is critical that all inside areas
of the booth are visible to the naked eye for cleaning.
Hidden areas, such as tight angles and enclosures, make
color change difficult and more time consuming.
The cartridge booth recovers oversprayed
powder by means of a self-cleaning cartridge contained
within a removable color module. When a color change is
required, the pumps, hoses, guns, and booth canopy are
cleaned, powder deposited into the color module, and
then replaced with the next color module. Painting can
then resume. As with all other types of booths, the cleaning
of the pumps, guns, and booth is completed with the
fan motor in operation so the powder can be collected
into the color module.
The cyclone booth requires all the steps of a
cartridge booth, and in some cases, cleaning of the ductwork
and lower one-third of the cyclone. In general, color
change for the cartridge booth is much quicker and easier
than the conventional cyclone.