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All AMU Filters You Will Find in a Paint Booth

Air makeup units (AMUs) are an essential part of any paint booth set up. In its basic functionality, an AMU replaces the air within the cabin. It also helps to balance the air pressure and control how much air is being added to the booth. As with many other parts of a booth, the AMU has filters that ensure the air being introduced to the cabin is clean and free of dirt and dust.

What many painters don’t realize is that AMUs have more filters than they think! Most air makeup units come with three different types of filters. Watch our video below and continue reading our blog to learn more.

Types of Air Makeup Units

Accudraft offers different styles of AMUs, depending on which paint booth model its being added to. However, even if the type of air makeup unit is different, all generally perform the same. The only difference between AMUs is how they work, not how well they work.

What Filters are in an Accudraft Air Makeup Unit (AMU)?

The AMU’s filter locations may differ slightly than what’s in the above video, so it’s important to inspect your AMU to locate all filters or reach out to its manufacturer. Every air makeup unit comes with three types of filters that help to keep the new air clean. Here’s everything you need to know about the three types of AMU filters.


After air comes into the main stack, it hits pre-filtration filters before it gets into the cabin through the ceiling filters. It’s crucial to regularly replace pre-filters if they are dirty; otherwise, they could become clogged and release debris into the cabin, resulting in poor paint jobs. If your paint booth uses a KD AMU, the pre-filter will be a pocket style; if your paint booth uses a direct drive AMU, the pre-filter will be a diagonal, fiber glass style.

Pro-tip: If there is a lot of debris when changing ceiling filters, it could be due to a lack of a pre-filter or a clogged pre-filter.

Secondary Exhaust Filters

Secondary exhaust filters are typically located on the rear side of an AMU. They should be regularly changed to avoid overspray on the exhaust fan and the risk of having its motors burn up (which is very expensive to replace). Clogged secondary exhaust filters can cause premature wear on the exhaust fan and use more power to keep the same speed, driving up operational costs.

Again, depending on if your AMU is a KD or direct drive, it will use pocket or fiber glass filters. If your AMU uses a pocket style for filtration, it could increase the lifespan of the filters. However, shops can more easily buy precut fiber glass filters that slide right into place, which helps to cut back on how long it takes to replace the filter.

Pro-tip: If your shop is unable to find and purchase pocket style filters, most AMUs can be retrofitted to hold fiber glass grates instead.

Recirculation Filters

Recirculation filters come into play within the bake cycle. As the heated air is being recirculated within the cabin, these filters catch any dirt and dust that may have snuck into the air. Unlike the other two types of AMU filters, these ones can be checked monthly, as they will accumulate dirt less frequently due to its location within an air makeup unit. However, that doesn’t mean they should be forgotten about!

To learn more, about paint booth filters, check out our YouTube channel.

Professional Paint Booth Maintenance and Service

We understand that routine maintenance like replacing filters can take too much time out of the production day. But not keeping up with filter changes can lead to pressure issues, overran motors, premature mechanical wear, and other issues. Shops with busy schedules should work with Accudraft’s service team to schedule regular maintenance so your paint booths never have to suffer from dirty filters. Contact us to learn more about our maintenance plans!