Prep Stations "101"
as they have come to be called, encompass a wide varity of impressions. Mostly used in the auto body industry,
many tasks are performed in prep stations, including sanding & taping (preparing the vehicle for painting in a fully enclosed
paint booth) as well as light priming, light painting and the application of other top coats.
Note should be taken that
a prep station is not designed to take the place of a complete paint booth for overall, complete vehicle refinishing.
Prep stations are available
in two (2) categories: Stationary (fixed, built in place) and mobile (on wheels). A "stationary"
prep station requires the vehicle be moved to the fixed prep station. A "mobile" prep station
allows the prep station to be moved to the vehicle.
Stationary Prep Stations: A "Basic" prep station usually
consists of an exhaust filtration system to clean the air and collect any overspray before it is exhausted from the shop to
the outside atmosphere. It should be noted that anything exhausted (emitted) from a shop to the outside
atmosphere must meet any applicable EPA requirements. This basic prep station is considered a "negative"
airflow design, meaning that by exhausting air from in the shop, it will create a "negative" air pressure in the
building, relative to the outside atmosphere. That is why, when the exhaust fan from the prep station is
running, especially at full RPMs, and the doors to the shop are closed, it can be difficult to open the shop door.
In essence the negative pressure in the shop is "sucking" at the door for replacement air, holding it closed.
The same principal exists in a "negative" pressure paint booth.
At Future Cure we actually use the rear
section of our "Rear Wall Exhaust" paint booth as our basic "Exhaust Wall"
prep station configuration, which is the simplest of prep station designs and least expensive. It has a
filtration system (99.6% efficient) and an exhaust fan assembly. Note should be taken that the exhaust
fan assembly is approved for hazardous locations involving paint residue and fumes.
The exhaust fan system in an Exhaust Wall has to be much more powerful than that in a paint booth because in
a paint booth the air is "channeled" thru the booth and over the vehicle. That "channeling"
helps increase the air velocity over the vehicle. An Exhaust Wall pulls air from 360° around
the area and only a small portion is "channeled" around the vehicle. This usually requires a
larger motor & CFM.What must be considered, especially in the winter when the
heat is on, is that this exhaust fan will not only remove unwanted dust and overspray from the shop...but
also most of the heat. Therefore a VFD (variable frequency drive) is recommended to adjust the speed of
the exhaust fan. Slow it down, when not a lot of air movement is required, and speed it up when more air
movement is needed.An Exhaust Wall's capabilities can be expanded by adding a full
ceiling with lights and a surround curtain. This is known as a "Basic Prep Station".
Because it is suspended from the ceiling, several criteria take place...First, installation costs are higher.
It is difficult and labor intensive to work from "scissor lifts" suspending the apparatus from the ceiling.
Also, the prep station ceiling can weigh as much as 2.5 tons and the shop ceiling must be able to support the weight.
These added features (full ceiling and complete surround curtains) will enclose the work area of the prep station...but
remember the "negative" air flow condition still exists and when you turn
the exhaust fan on it will "suck" the curtains in...towards the exhaust fan...and "suck" the hot air from
the shop. Therefore, for the best application
scenario a "Prep Station with Air Make-up" is the best way to go. The
"Air Make-up" will add "Positive Pressure" to the prep station and make
it perform like a full paint booth (with curtains instead of walls). Note: most heated prep Stations do
not have a "Bake" cycle. With Air Make-up, slightly more heated air
is forced into the prep station than is exhausted by the exhaust fan...giving the area inside the prep station a "positive"
pressure balance...and the doors of the shop will no longer be "sucked" closed.Unfortunately,
by the nature of its design and added installation costs, a prep station's costs can be as much as, if not more than
a heated paint booth. It does offer the flexibility of curtained walls, but lacks the bake capabilities
of a true paint booth. Prep stations are available in single, as well as multiple (up to 4 car) configurations. Mobile Prep Stations: With most shop sizes
at 3000 to 5000, and even 10,000 square feet, sometimes moving the vehicle to a "fixed prep station" can be difficult.
Especially if the vehicle is up on the frame machine and you have to do any painting/priming of newly installed or
repaired components. This is where a mobile prep station, that can be easily be rolled to the work area,
performs best. Note: mobile prep stations also absorb welding fumes. "Mobile prep stations" are used for the
same purposes as a fixed prep...sanding of bondo and primers, as well as, the removal of overspray from base coat and top
coat component painting. The 2 major differences is it's mobility and it has no exhaust from the building.
Therefore, nothing is "emitted" from the building to the atmosphere. All contaminates
are "captured and controlled" at their point of generation...and because there is no exhaust from the building...no
heat loss...and no stack permits. Mobile prep stations are able
to "re-circulate" the purified air back into the work area because of a series of filters. There
is usually a 4 stage filtration system. The first being an inexpensive "pre-filter" to
collect bondo dust and overspray, easily cleaned and/or replaced as needed. Secondly
is the main contaminate filter designed to collect particulate and protect the third filter. The third
filter is a "suspended" carbon filter which cleans the air of VOCs, odors ,and any "gaseous" contaminates.
The fourth and final filter is a 3 micron "Pocket" filter. Pocket filters
allow a large surface collection area in a small footprint. Note: most spray booths us a 10 micron intake
filter. A 3 micron filter delivers air 3.3 times cleaner than a 10 micron...meaning the air coming out
of a mobile prep (the air coming back into the work area) is 3.3 times cleaner than the air in your paint booth. Mobile
prep stations can cost as little as 1/3 the cost of stationary.
As with any piece of equipment, you should check with local authorities concerning equipment
installations and uses.
The above is for informational purposes only.