Auto Body Paint Booths

There are numerous brands and styles of paint booths and they all use a different approach to filtering. The above picture shows a cross draft booth as the air is entering through the door (1) and moves across the booth through the exhaust filters (2). This design is not as common as it once was as we have seen the downdraft booths take over in popularity for several reasons. The downdraft booth blows air from the ceiling over the vehicle and the air exits through the floor. This gives you a clean air shower onto the car from above and pulls the paint over spray toward and through the floor The basic concept remains the same no matter what type of paint booth you are using. Your goal is to eliminate as much dust and debris as possible to keep it off of your vehicle during and after painting. The filters you choose to use are the most important part of this paint booth. You can spend $100,000 on the best booth on the market, but if you do not use quality filtration products your paint jobs will not be any better than if you had no booth at all. So let's take a look at the importance of each filter in the process, the intake filters and ceiling filters, and the exhaust filters.

DOWNDRAFT BOOTHS
1) Intake filter - The intake filters are typically located in the duct work which draws air in from either the roof or on the side of the building. This is the first stage of filtration. Because your ceiling filters are usually the most expensive filters to replace, you will want a quality intake filter to help those ceiling filters last longer. We recommend our Farr 30/30 pleated type pre-filters for this application, if at all possible. If the size of the filter needed does not allow for the Farr 30/30, a good quality, tackified (sticky) polyester panel filter is the next best option.

2) Ceiling filter - The ceiling filters are the final filters before the air hits the top of your vehicle. This is the most important filter in the downdraft booth and you want this filter to remove all the dust and debris which will blemish your paint job. Dust and debris particles which are larger than 10 microns in size are the ones which you will want the ceiling filter to remove. When buying this filter, look for a filter media which is rated 95% + at removing particles greater than 10 microns in size. (A micron is the unit of measure which determines the size of particles too small to measure in fractions of inches or millimeters.) To give you an idea of how big a micron is, the diameter of a human hair is about 10 microns. Salt can be between 20 and 50 microns. Any particles smaller than 10 microns will be engulfed by the paint and should not show a blemish. Ceiling filters are normally made from a thick polyester media with a dense scrim backing. When you look at this filter media from the side, it may have three layers of different densities. Another purpose of the ceiling filter is to diffuse the air so there is an even airflow on all parts of the vehicle. The ceiling filter is sometimes called the diffusion filter or diffusion media.

3) Floor or Trench Filter - These filters are almost always in the floor, but sometimes found toward the bottom of the wall of a paint booth. This filter's main purpose is to catch the paint over spray, but will also catch any leaves or other debris which finds its way into the booth. The EPA will want you to catch the paint over spray so the paint is not exhausted into the outside air. The other purpose of this filter, is to protect your cars in the parking lot, as you may see specs of paint on your vehicles if you are not catching the over spray. This is your least important filter. Often you will purchase rolls of this filter media in the correct width for your trench and then cut the media to fit the length. We have seen three different types of filters used in the trenches described below.

A) The most common is fiberglass paint arrestor which is normally green, but could be blue. When you purchase this fiberglass media you want to pay attention to the density of the fiberglass. The rolls or pads should be labeled in grams with the most popular being 14 grams (good), 18 grams (better), and 22 grams (best). With more grams of weight, the filter will have more fiberglass and catch more dust and dirt. While it catches more dust and dirt it will also fill up quicker. The 18-gram fiberglass seems to be a good compromise between removing enough particles from the air, and the length of time the filter will last.

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B) On occasion we have seen polyester used in the trenched. Polyester media should be more efficient at collecting paint which means you will need to change it more often also. Polyester is a little more expensive than fiberglass, but if you are trying to lengthen the life of your ceiling filters, it may be worth the extra cost. If your booth re-circulates the air after it goes through the floor this may be your best choice. If your booth exhausts the air after in goes through the trench, then the fiberglass will be your most cost effective solution. You can get polyester rolls with or without tackifier (sticky). For your trench filter you will want a dry polyester without tackifier.

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C) The third option is an absorbent paper mesh filter with a thin layer of polyester backing. While this may do the best job of catching and holding paint particles, the high cost usually warrants a different choice. We have seen this type of filter installed as the original filter when the booth is delivered, but then the body shops switch to polyester or fiberglass rolls when they see the cost of replacing the paper media. There are still some applications where this is the best choice, however.

Whatever the specifications are for your booth, dp filters has the right solution for you. If you are in the central Illinois area, we would be more than happy to come out and survey your needs and offer you the alternatives to fit your painting operations. Give us a call at 1(800) 397-1590 or email us at the link below.