OTC Insights Team
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While the nozzles and sprayers are important components of a paint or spray booth, the filtration and airflow systems are just as important. They are critical to the booth’s efficient operation.
The filtration system of the paint booth is necessary to remove potential contaminants from the air entering the booth. The smallest particles can damage the finish and ruin the product. Controlled airflow helps control and direct the spray to ensure a consistent and high-quality finish.
If that wasn’t enough, safety regulations mandate exhaust filtration for paint booths, setting requirements for industries and chemical products.
Proper filters are a core element of regulating airflow and the booth filtration system.
A Close Look at Paint Booth Filters
Most filters are made of layered fiberglass or polyester. The configuration and composition of the fibers, the density, and the setup of the filter will determine how the filter will perform in the booth. Also, the configuration of the booth, the materials and paint used, and your process needs will dictate the filters used.
The Three Types of Paint Booth Filters
Selecting a different filter will affect the performance of the paint booth, both the airflow into and out of the booth, and the filtration efficiency. It’s important to use the correct filters.
Intake Filters
The smallest particle entering the paint booth, even a particle as small as 10 microns, can ruin a paint job. The intake filter removes contaminants, allowing clean air into the booth.
Crossdraft paint booths typically use linked panel filters or internal-supported filters, as these don’t require mounting hardware like clips to eliminate leaks. Downdraft paint booths use diffusion pads as filters, ensuring an even spread of air in the booth.
The efficiency of the filter is measured by a MERV (Minimum Efficiency Reporting Value) rating. This rates the effectiveness of the filter in removing particulates from the air. Crossdraft booths will typically have a rating of MERV 6 to 8, as this is all that is a necessary. A downdraft booth relies on airflow, requiring at least a MERV 10 rating, removing more than 99 percent of all particles 10 microns or larger.
Exhaust Filters
Exhaust filters work at the other end of the filtration and airflow systems in a paint or spray booth. The intake filter cleans the air coming into the booth, while the exhaust filter removes the dangerous chemicals and emissions from the paint before it enters the outside environment, or the overspray damages the fans and internal components in the booth.
This means exhaust filters need to absorb and capture both the liquid aerosols, chemicals, solids, and the overspray that are released during the painting and finishing process. These are often highly toxic and can be dangerous. The exhaust filters need to hold paint and continue functioning, so that you aren’t replacing the filter constantly. It also needs to prevent leakage while maintaining air pressure in the booth, preventing the captured paint from hardening.
Typically, single-stage filters designed for the booth configuration are used. In downdraft booths, an exhaust pit filter is usually used, while crossdraft booths use wall and plenum filters.
Air Makeup Filters
Air makeup filters trap large contaminants before they reach the air makeup unit (AMU), a system for pressurizing air in the paint or spray booth. In this way, the air makeup filter acts as the first line of defense for the booth, helping to extend the life of the more expensive filters, protecting the delicate internal components, and ensuring efficient booth operations.
As the first line of defense, there are many types and styles of air makeup filters such as pad filters, pocket and bag filters, cleanable and reusable aluminum filters, and the standard panel filter.
Building a Maintenance Plan for Filters
Filters in the paint booth need to be regularly replaced to properly function. Any maintenance plan for the paint or spray booth should include a schedule for filter replacement, both intake and exhaust.
That schedule should be designed around the work you do, the booth recommendations, and the best practices of the filters you use. A tight schedule with frequent or continual work will need more frequent filter maintenance. Lower quality filters will also require frequent replacement.
Evaluate and Adjust your Maintenance Plan
Evaluate your maintenance schedule for filters by taking regular readings with a magnehelic pressure gauge. If you are frequently getting readings outside the recommended range for the booth, you may need to increase the frequency of filter replacement. Use the data to create a schedule that balances cost efficiency with paint and finish quality and filtration needs.
Because the air makeup filters handle larger contaminants and are so closely tied to the air pressure system in the booth, they’re a good place to start looking when there are air pressure problems. If you have too much airflow, then the filters may not be correctly placed. If there isn’t enough pressure or airflow, then a filter may be clogged. Don’t hesitate to replace filters sooner if there is a problem.
Over time, as you refine and adjust your maintenance plan and look for opportunities to optimize, you should develop a comprehensive filter strategy.
If you have questions, or need help with your paint or spray booth, then contact the Finishing, Dispensing, and Filtration team at OTC Industrial Technologies. Set up a consultation with them and get the information and solutions you need to overcome challenges and increase efficiency at your facility.
