/ Field knowledge · IMC 502.16
Do not copy the gasoline 18-inch inlet onto a hydrogen bay.
Lighter-than-air fuels do not sit on the slab like gasoline. IMC 502.16: repair garages for compressed natural gas (CNG), liquefied natural gas (LNG), hydrogen, or other lighter-than-air fuels get mechanical exhaust with inlets low, outlets high, a rate based on room volume, and automatic shutdown of fueling when exhaust fails. Hydrogen repair must also meet NFPA 2. Copying the 18-inch gasoline rule onto a hydrogen bay is the miss 502.16 is written to catch.
Educational 2024 International Mechanical Code (IMC) 502.16 from Daily Code Talk (same post as 502.11–502.20). Confirm the adopted edition. Distinct from 502.1.2 gasoline ≤ 18 in AFF and 304.5 generating/refueling. This is not a repair-garage design. The code does not put a single cfm number on this page — the rate is based on the room volume; put that basis on M-601.
- 502.16: mechanical exhaust, inlets low, outlets high, rate based on room volume, automatic shutdown of fueling on exhaust failure.
- Hydrogen repair: also NFPA 2. Fire-marshal first. Do not treat this as a 404 CO-sensor garage.
- Related 502.11–502.19 (process, not room name): projector 200/300 cfm per lamp; organic coating ≥ 1 cfm/ft² of solid floor, pickup at floor level; source-capture on tailpipes where engines run in place (exceptions: EV-only, 1- and 2-family, move-in/move-out only).
- Do not manifold this exhaust into environmental return. Do not copy 502.1.2’s 18 in AFF gasoline pickup onto a CNG/hydrogen bay.
On the set: M-001 “SPECIAL EXHAUST — IMC 502.16” with inlet/outlet elevations, volume-based rate, and the fueling-shutdown interlock. Electrical: exhaust failure kills the fueling circuit, not a note. Hydrogen: NFPA 2 path on the same sheet as 304.5 if generating/refueling is also in the building.
A hydrogen bay with a low gasoline-style inlet and no fueling interlock
Light gas goes to the ceiling. Exhaust failure that leaves the dispenser live is the inspection item. 304.5 is generating/refueling; 502.16 is the repair garage — both can exist on one site.
Source: Daily Code Talk — IMC 502.11–502.20 · tool: Low inlet / high outlet screen · gasoline: 502.1.2 18 in · hydrogen: 304.5 · garage: 404.
What to send
Whether this is CNG, LNG, or hydrogen repair (or gasoline), a section showing inlet and outlet height, and whether fueling shuts down on exhaust failure.
If the hydrogen bay uses the gasoline 18-inch inlet
Send the section and the fuel type. Masterbuild will say whether 502.16 still has no high outlet — or 502.16 still has fueling live when the exhaust is down.
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. Inlets low / outlets high, volume-based rate, automatic fueling shutdown, and NFPA 2 for hydrogen repair are 2024 IMC 502.16 education from Daily Code Talk — not a repair-garage design and not a cfm. This page is not legal advice.