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 with "negative" pressure.
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.