Scale is the story. A large-vehicle downdraft moves air across a working area several times the footprint of a car booth, which means the ceiling filter bank and the exhaust arrestor field scale up with it. Owners who buy panel-by-panel at this size overpay badly; case and roll quantities are the correct unit of purchase.

Intake side. The ceiling plenum carries diffusion media across the full cabin length. At truck-booth scale, a mixed program is common: panel media where the plenum grid takes framed sets, roll blanket where it takes cut lengths. Saima did not publish the Grandi Mezzi grid layout in the material we hold, and layouts varied by installation since these booths were often built to the customer's building. We treat every one as a measured fitment: grid photos plus one panel measurement and a bay length, cross-referenced by the WERCS service team against distributor and manufacturer catalogs.

Exhaust side. Under-floor arrestor media catches overspray before the exhaust fans. Fiberglass pad and roll stock are the workhorse choices at this scale because they cut to pit dimensions and load predictably. Industrial primers and high-solids fleet coatings load exhaust media faster than automotive basecoat, so a Grandi Mezzi spraying chassis black or equipment enamel should expect shorter exhaust intervals than the same booth spraying refinish clears.

Buying rhythm. The economical pattern is a standing order: full exhaust changeout quantities on a fixed cadence, ceiling media at a slower multiple, tuned after the first two cycles.

Big booths carry the same rulebook as small ones, with higher stakes. OSHA 29 CFR 1910.94(c) requires maintained ventilation across the whole working zone, and on a cabin this long, degraded exhaust media shows up as dead zones where overspray hangs around the painter. NFPA 33 treats accumulated overspray in an under-floor pit as fire load, and a truck booth's pit is large enough that a neglected changeout becomes serious accumulation. EPA NESHAP 6H applies when target-HAP coatings are sprayed, as many fleet and industrial coatings are, and its filtered-enclosure and recordkeeping requirements are satisfied by the documented media schedule a standing order produces.