Intake side. Intake media sits in the ceiling section toward the front of the cabin, where make-up air enters before sweeping back and down. Diffusion-grade media here keeps incoming air clean and evens the flow so the diagonal path develops properly instead of jetting. The intake bank covers only part of the ceiling, so this is an inexpensive position to keep fresh.

Exhaust side. The rear filter bank carries the arrestor media that catches overspray, and in a semi-downdraft it works hard: the diagonal path delivers overspray to the rear wall at working height, concentrated. Fiberglass arrestor pad or roll stock is the standard fill. The 8550-NP record in our catalog is not yet field-verified, so we confirm frame dimensions and opening count from your measurements or photos before locking a kit; 8500-series booths were built in enough configurations that assuming is how wrong media gets shipped.

Cycle math. Expect the rear bank to set the change rhythm and the intake ceiling section to run several cycles longer. Watch the manometer trend, not the calendar date: rising static across the exhaust is the change signal.

OSHA 1910.94(c) requires spray-finishing ventilation to maintain design velocity while spraying, and on a semi-downdraft the exhaust bank's condition is that velocity's limiting factor, so the manometer discipline described above is also the OSHA discipline. NESHAP 6H requires exhaust filtration on target-coating operations, maintained per manufacturer recommendations, with records; the 6H maintenance log and your filter change log should be the same document. NFPA 33 governs overspray accumulation and combustible loading, which for a rear-bank booth means changing arrestor media before it saturates and keeping the removed media handled as the loaded waste it is.