Combustible dust isn't a "maybe." If the process can create an explosive condition, the exhaust system needs an explosion-control strategy that matches IFC and is documented on the drawings.
Plain English:
510.1.5 explosion control is required (IFC-driven) Explosion control must be provided per the International Fire Code for systems conveying:
1. Combustible dust, or
2. Combustible refuse/stock that produces combustible dust, when concentrations/conditions could create a fire or explosion hazard.
If you claim "no hazard," that determination must be backed by a Dust Hazard Analysis (DHA) per IFC 2203.2.
510.1.5.1 screens at safety relief vents
If a screen is installed at a safety relief vent, it must be attached to readily release under explosion pressure (i.e., it can't "hold" the vent closed).
510.1.5.2 relief vent hoods/cowls/covers
Relief vents must have an approved noncombustible cowl/hood, or a counterbalanced relief valve/cover, arranged to prevent escape of hazardous materials, gases, or liquids.
On Plans: Why it matters
Common redlines: "explosion vent by others," no DHA basis, vent screens detailed like bird screens (non-releasing), and relief vent terminations that can discharge hazardous material toward people/equipment.
Code Path: Where to show it
M-001: "EXPLOSION CONTROL PER IFC (DHA PER IFC 2203.2 WHERE APPLICABLE)" + responsibility note (RDP/owner/industrial hygienist as applicable).
Plans/Roof plan: relief vent location, discharge direction, and separation from occupied areas/intakes where relevant.
Details: vent device/cowl/relief valve, and the "screen releases under pressure" requirement.
Equipment schedule/submittals: explosion-control method type (per IFC), basis reference to DHA (if used).
Check: Do
Put a clear DHA/IFC trigger note on the drawings when combustible dust exists.
Call out that screens at relief vents must release under explosion pressure.
Coordinate relief vent discharge so it doesn't create a new hazard.
Review Risk: Don't
Don't cover explosion control with a generic note and no IFC/DHA basis.
Don't use fixed screens that can restrict or defeat explosion relief.
Don't aim relief vent discharge toward walkways, doors, or service areas.
Field Tip:
Run the "DHA -> RELIEF PATH" check:
1. Is there combustible dust? If yes -> IFC explosion control required unless a DHA says otherwise.
2. If there's a relief vent: where does it discharge, and will any screen release under pressure?
If either answer is unclear -> expect plan review comments.
Masterbuild QA Lens
Dust, stock, and refuse conveying systems under Section 510 must be segregated from all other mechanical systems. Confirm no cross-connections between the conveying exhaust and any HVAC, ventilation, or grease exhaust system. The fan and motor must be rated for the dust or material classification and the listing basis stated on the schedule.
Drawing / Submittal Check
For 510.1.5 (explosion control and relief vents): the drawings must show the explosion relief vent locations, the vent area calculation (referenced standard and Kst value for the dust), the vent discharge direction (away from occupied areas, egress, and air intakes), and the vent panel type. Explosion relief vent details that do not show the discharge direction or the vent area basis will not survive first review.
Common Review Risk
Explosion relief vent discharge direction is the most common correction on conveying system explosion protection. The vent must discharge away from occupied areas, egress, equipment, and adjacent buildings. A vent that is sized and located correctly but points toward an egress door will require relocation. Coordinate the vent discharge direction with the site plan and the building occupancy before the permit is filed.
When To Escalate
Escalate when the explosion relief vent location conflicts with an occupied area, an egress path, or an adjacent building that cannot be relocated or protected. Relief vent discharge direction conflicts require AHJ approval of an alternative protection strategy - either a different vent location, a duct-away system, or chemical suppression. None of these alternatives is inexpensive.
Kitchen Exhaust Coordination
For kitchen exhaust, tie the hood schedule, appliance lineup, grease duct route, cleanouts, fan discharge, fire suppression interface, and make-up air strategy into one reviewable story.
Special Exhaust Coordination
For specialty exhaust, start with the contaminant and source. Then confirm capture method, duct material, routing, discharge, separation, controls, and whether another consultant or AHJ review is required.