/ Field knowledge · IMC 502.17
A ceiling fan over a buffer is not 502.17.
A tire-buffing machine is not a shop-vac in the corner. IMC 502.17: rooms that use rubber cement or flammable solvents follow NFPA 91 (Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Particulate Solids). Buffing machines connect to dust collection so rubber dust cannot accumulate. A ceiling fan over the buffer is not collection. Recirculating that dust into the shop without a 510.1.3 path is a different — and worse — miss.
Educational 2024 International Mechanical Code (IMC) 502.17 from Daily Code Talk (same post as 502.11–502.20). Confirm the adopted edition. Distinct from 510.1.3 dust recirculation (99.9% at 10 microns, under 25% LFL, monitored) and 502.7 flammable finishes. This is not a dust-collector design and not an NFPA 91 listing. There is no cfm on this page — the collector is sized to the machine and to NFPA 91, not to a toilet-fan table. Packet: 502.17 PDF · ES.
- Rubber cement / flammable solvent rooms: NFPA 91, not “exhaust as required.”
- Buffing machines: connected to dust collection. The point is that dust does not accumulate on the floor, in the ceiling, or in the return.
- Do not manifold buffing dust into house return or toilet exhaust. Do not call a wall fan “collection.”
- If you intend to send cleaned air back to the shop, that is a 510.1.3 question — all three parts, or outdoors.
On the set: tag the room process (cement / solvent / buffing), name NFPA 91 on the schedule, and show the collector connected to each buffer. If recirculation is claimed, send it to the 510.1.3 screen instead of hoping 502.17 covers it.
A buffer under a ceiling grille, rubber dust on the slab
The dust is combustible. The cement vapor is flammable. Neither belongs in the house return. Pickup at the machine, collection that actually captures, discharge or a documented 510.1.3 recirc path.
Source: Daily Code Talk — IMC 502.11–502.20 · tool: Buffing / NFPA 91 screen · recirc: 510.1.3 · spray: 502.7.
What to send
Whether this is cement/solvent, buffing, or both; whether each buffer has a collector takeoff; and whether the collector discharges outdoors or back into the shop.
If the buffer only has a ceiling fan
Send a photo of the machine and where the dust goes. Masterbuild will say whether 502.17 still has no collector on the buffer — or 502.17 still dumps rubber dust into the return.
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. Confirm the adopted edition. NFPA 91 for rubber-cement / flammable-solvent rooms, and dust collection connected to buffing machines so dust cannot accumulate, are 2024 IMC 502.17 education from Daily Code Talk — not a collector design and not a cfm. Recirculation is IMC 510.1.3, not this section. This page is not legal advice.