What loads the media. Primer-surfacer overspray is high-solids by design and blinds arrestor faster than basecoat. Add dry-sanding dust that any vacuum system only partially captures, and prep station media routinely reaches change condition well before an equivalent pad in a topcoat booth would. Plan cycles around that reality rather than around booth habits.

Supply and capture stages. Supply-side media keeps the work zone air clean enough that fresh primer does not seed itself with dust, and capture-side arrestor keeps particulate out of the exhaust path and the shop. Because the dossier for the 4000D documents the model without recorded dimensions or a verified slot layout, we do not publish panel counts or sizes for it; prep stations also vary by installation (full enclosure versus curtained open front) in ways that change the media list. The fitment check settles your configuration with a nameplate photo and a few measurements, once.

Cycle math. A practical rule for prep environments: whatever interval you would run in a finish booth, expect the prep station to demand changes noticeably sooner, tuned by primer volume and how much sanding runs dry versus wet. High-holding polyester arrestor typically earns its price in this duty by extending intervals a fiberglass pad cannot hold in dust-heavy service.

Prep work sits squarely inside the rules shops sometimes assume are booth-only. EPA 6H (NESHAP Subpart HHHHHH) explicitly covers spray-applied coatings including primers, so priming in the 4000D belongs inside a filtered, ventilated enclosure with the same recordkeeping as the booth. OSHA 1910.94(c) applies to spray finishing operations wherever they happen, and OSHA also cares about the sanding-dust exposure the station's ventilation controls. NFPA 33 rounds it out: primer overspray accumulated in arrestor media is combustible loading. Dated change records for the prep deck carry the same audit weight as booth records, and are more often missing.