/ Field knowledge · IMC 502
Table 403 is not the 502 checklist.
IMC 502: if a process makes “bad air” (dust, fumes, heat, vapors, spray, smoke) that can irritate or affect health/safety, you owe exhaust — even if Table 403 does not name the room. A 502 schedule that says “NONE” still proves you ran the checklist.
Educational 2024 IMC 502. Confirm adopted edition, MAQs, and fire-code occupancy. This is not a hazardous-exhaust design.
- 502.1. Process exhaust beyond Table 403 rooms.
- 502.2–502.7. Aircraft fueling, battery rooms, dry cleaning, flammable finishes, spray, dipping, electrostatic, powder coating, floor resurfacing — specific rates (cfm/ft², face velocity) and “run while the process runs.”
- 502.8 hazmat. Over MAQ: often ≥ 1 cfm/ft², usually continuous; emergency shutoff; pickup height by vapor density; no recirculation of contaminated air to occupied spaces.
- 502.9. Extra rules for medical gases, corrosives, cryogenics, flammable liquids, toxics, ozone, LP-gas, silane — local capture; DCT: 200 fpm at gas cabinet/enclosure faces; scrubbers where leaks create dangerous vapors.
- 502.10–502.20. HPM fabs, gas rooms, projector rooms, garages/pits, gaseous-fuel repair, tire recapping, firing ranges, nail stations — purpose-built exhaust, pickup location, sometimes interlocks.
Room on the A sheets, missing on M-601
Do not recirculate spray, flammable-finish, hazmat, HPM, or firing-range exhaust unless every code condition is documented. Do not combine those streams with general return. Battery rooms: type, hazard basis, ventilation calc, control sequence, alarm, exhaust path — all traceable.
Source: DCT 502 summary · tool: 502 check · 310: explosion control.
What to send
Room list and what actually happens in each room (charging, spray, nails, medical gas). Architectural occupancy vs fire occupancy if they disagree.
If the room is not in Table 403 and still smells like a process
Send the room list and the process. Masterbuild will say whether 502 is even on the path — or Table 403 was used as a substitute.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval.