Accudraft · Semi-downdraft
Accudraft MX300 Semi Downdraft
Filter kit, alternatives, and current pricing for the MX300 Semi Downdraft.
Required filters
Recommended kit for this booth
3 matched filters across 3 slots.
Complete kit total · $521.10
Intake side (clean air going in) (2 slots)
AMU pre-filter
Pleated AMU pre-filter panel · 20x25x2
In stock · ships in 24hPleated AMU Pre-Filter Panel 20" x 25" x 2"
BFP-AMUP-20X25X2· 60–90 day cycle$200.50
Ceiling intake
Ceiling diffusion polyester · 20x25
In stock · ships in 24hCeiling Diffusion Polyester Panel 20" x 25"
BFP-PCD-20X25· 30–60 day cycle$160.89
Exhaust side (overspray coming out) (1 slot)
Exhaust Wall
Accordion / Andreae paper · 20x20
Special order · 1–2 weeksAccordion Paper Baffle Arrestor 20" x 20"
BFP-ACCP-20X20· 14–28 day cycle$159.71
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Accudraft MX300 Semi Downdraft Filter Fitments
Semi downdraft airflow is the reason this booth exists. A true downdraft needs a pit or a raised basement floor; a crossdraft pushes overspray horizontally past the painter. The semi downdraft splits the difference. Air drops in from a ceiling plenum at the entry end, so fresh filtered air arrives above the work, then the exhaust wall at the back pulls it down and away in a long diagonal. Shops get most of the finish-quality benefit of top-down air without the excavation bill. The MX300 is one of ten Accudraft models in our booth catalog.
Quick answer
The Accudraft MX300 is a semi downdraft spray booth: makeup air enters through a filtered ceiling section near the front of the cabin, sweeps diagonally down the length of the booth, and exits through a filtered exhaust plenum at the rear. That geometry gives the MX300 two filter positions to maintain, intake diffusion media overhead and overspray arrestor media at the exhaust end. Our fitment record for this model is still in verification, so we do not ship kits on assumed sizes. Run a fitment check with your frame dimensions and panel counts, and the WERCS service team confirms the kit before anything is boxed.
How MX300 Semi Downdraft shops choose filters
Intake side. The ceiling section takes intake diffusion media, the stage that decides how clean the air landing on your paint actually is. Tacky-finish polyester diffusion media is the standard recommendation for color work because it holds fine dust that would otherwise become nibs in the clear. This is the position where cheap media shows up in the finish first.
Exhaust side. The rear plenum carries the overspray load. In a semi downdraft, everything the gun atomizes and the panel does not catch ends up here, so the exhaust arrestor is the fastest-loading position in the booth. Fiberglass arrestor pad is the common baseline; multi-stage arrangements raise capture efficiency where coatings or local rules demand it.
Verification status. The MX300 fitment file in our database is flagged needs-verification: panel counts and frame sizes for this specific model are not yet documented to the standard we publish. Do not bulk order on this page alone. Send us the grid layout, or photos of the ceiling section and exhaust wall with a tape measure in frame, and we confirm exact sizes and media types before the first kit ships. Once your booth is measured, the record is locked to your account and reorders are one click.
Regulatory landscape
If you spray coatings containing target HAPs, EPA 6H (40 CFR 63 Subpart HHHHHH) requires the booth to be fitted with filter technology demonstrated to achieve at least 98 percent capture efficiency, and it expects the booth to be operated with filters in place and maintained. OSHA 1910.94(c) treats the filter bank as part of the ventilation system: airflow must stay adequate, which means changing exhaust media before loading chokes the fan. NFPA 33 adds the fire side, since loaded arrestor media is combustible fuel. Documented change-outs on a schedule satisfy all three conversations with an inspector.
Who runs the MX300 Semi Downdraft
The MX300 shows up most often in independent collision shops that outgrew a crossdraft but could not justify concrete work for a pit, since the semi downdraft bolts to a flat slab. The second group is mixed-work shops, part collision, part industrial coating, that want better air over the panel without a full downdraft budget. Third are satellite locations of multi-shop operators, where the main store runs a premium downdraft and the secondary site runs an MX300 for overflow and smaller hits.
MX300 Semi Downdraft filter FAQs
Which filter positions does the MX300 actually have?
Two working positions: an intake diffusion stage in the ceiling section near the booth entry, and an exhaust arrestor stage at the rear plenum. There is no floor filter, because a semi downdraft exhausts through the back wall rather than through a pit.
Why will you not just sell me a kit from this page?
Because the MX300 fitment record is still marked needs-verification in our catalog, and shipping guessed sizes wastes your money and your downtime. A fitment check takes a few minutes: frame measurements or photos of both grids. After that, your sizes are confirmed by the WERCS service team and stored, and every reorder is exact.
Does the exhaust wall on a semi downdraft load faster than on a crossdraft?
It loads at least as fast, and often faster, because the diagonal airflow concentrates overspray onto the rear plenum rather than distributing it along a long side path. Watch the manometer rather than the calendar, and change the arrestor when the reading crosses the change point marked for your booth.
Can I run higher-grade intake media for finish-critical work?
Yes. The intake ceiling section is where media quality translates directly into fewer nibs, and stepping up to a heavier tacky polyester diffusion pad is a common move for shops doing blueprint or high-end refinish work. Confirm the frame depth during the fitment check so the upgraded media seats correctly.
Is the MX300 covered under EPA 6H like a full downdraft?
Yes. 6H applies based on what you spray, not on airflow layout. If your coatings contain the target HAPs, the MX300 needs filter technology meeting the 98 percent capture-efficiency requirement and a maintained change-out practice, exactly as a downdraft would.
Sources
Primary references cited on this page.
- EPA 40 CFR Part 63 Subpart HHHHHH (NESHAP 6H)https://www.epa.gov/stationary-sources-air-pollution/national-emissions-standards-paint-stripping-and-miscellaneous
- OSHA 29 CFR 1910.94(c), Ventilation: spray finishing operationshttps://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.94
- NFPA 33, Standard for Spray Application Using Flammable or Combustible Materialshttps://www.nfpa.org/codes-and-standards/nfpa-33-standard-development/33
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