☣️ UN 0421 • CLASS 1
UN 0421 — Flares, aerial
Placard: Explosive 1.2G. ERG Guide 112. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 0421 Quick Details
UN 0421
Product name: Flares, aerial
DOT Class: 1
Placard type: Explosive 1.2G
ERG Guide: 112 (check current ERG)
Initial isolation: ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 feet) in all directions; evacuate area 800 meters (0.5 miles) if fire is involved
Common Hazards of UN 0421
- Projection and fragmentation hazard on initiation.
- Blast overpressure in immediate area.
- Sensitive to heat, shock, or electrical current.
- May initiate other explosives in proximity.
Chemical Identity & Physical Properties
| Also known as | Aerial flaresPyrotechnic flaresSignal flaresIllumination flaresMilitary flares |
| Appearance | Pyrotechnic devices typically consisting of metal or cardboard tubes containing combustible compositions that produce intense light and heat. May be various colors depending on formulation. |
| Flash Point | Not applicable (pyrotechnic composition) |
| Boiling Point | Not applicable (pyrotechnic composition) |
| Vapor Density | Not applicable (solid pyrotechnic device) |
| Water Reactivity | May contain water-reactive metals such as magnesium or aluminum; avoid water application on burning flares |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 0421
Extinguishing Media
Do not use water or foam; use dry sand, earth, or approved dry chemical for small fires; evacuate area for large fires
PPE Requirements
⚠️ Level B minimum with full protective clothing; SCBA required; maintain distance due to projection hazard; explosive fragmentation risk
Isolation & Evacuation
ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 feet) in all directions; evacuate area 800 meters (0.5 miles) if fire is involved
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 112).
First Actions for a UN 0421 Incident
- CALL 911. Then call emergency response telephone number on shipping paper.
- Isolate minimum 500 meters; stage upwind and uphill.
- Request Hazmat + law enforcement immediately.
- Control ignition sources; deny unauthorized entry.
- Do not approach — projectile/fragmentation hazard.
- Consult current ERG Guide 112 and follow SOP/SOG.
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📋 Copy & Share Field Card
UN 0421 — Flares, aerialHAZMAT RADIO NOTE — UN 0421
Product: Flares, aerial
Class 1 / Explosive 1.2G / ERG 112
PPE: Level B minimum with full protective clothing; SCBA required; maintain distance due to projection hazard; explosive fragmentation risk
ISOLATION: ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 feet) in all directions; evacuate area 800 meters (0.5 miles) if fire is involved
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 0421 — Flares, aerial
Class: 1 | Placard: Explosive 1.2G | ERG Guide: 112
Appearance: Pyrotechnic devices typically consisting of metal or cardboard tubes containing combustible compositions that produce intense light and heat. May be various colors depending on formulation.
Water Reactivity: May contain water-reactive metals such as magnesium or aluminum; avoid water application on burning flares
Extinguishing: Do not use water or foam; use dry sand, earth, or approved dry chemical for small fires; evacuate area for large fires
PPE: Level B minimum with full protective clothing; SCBA required; maintain distance due to projection hazard; explosive fragmentation risk
Isolation: ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 feet) in all directions; evacuate area 800 meters (0.5 miles) if fire is involved
— Key Hazards —
• Projection and fragmentation hazard on initiation.
• Blast overpressure in immediate area.
• Sensitive to heat, shock, or electrical current.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper.
• Isolate minimum 500 meters; stage upwind and uphill.
• Request Hazmat + law enforcement immediately.
• Control ignition sources; deny unauthorized entry.
SOURCE: allfirefighter.com/hazmat/un/0421 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN0421 Flares, aerial Cls1 ERG112 | ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 fe | allfirefighter.com/hazmat/un/0421SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/0421
Related UN Numbers in Class 1
Discovery block for training / quick reference. Always consult the current ERG + your SOP/SOG for operations.
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Frequently Asked Questions about UN 0421
Projection and fragmentation hazard on initiation. Blast overpressure in immediate area. Sensitive to heat, shock, or electrical current. May initiate other explosives in proximity.
CALL 911. Then call emergency response telephone number on shipping paper. Isolate minimum 500 meters; stage upwind and uphill. Request Hazmat + law enforcement immediately.
Level B minimum with full protective clothing; SCBA required; maintain distance due to projection hazard; explosive fragmentation risk
Water reactivity: May contain water-reactive metals such as magnesium or aluminum; avoid water application on burning flares. Recommended extinguishing: Do not use water or foam; use dry sand, earth, or approved dry chemical for small fires; evacuate area for large fires.
ERG Guide 112 recommendation: ERG 112: Isolate spill or leak area immediately for at least 500 meters (1640 feet) in all directions; evacuate area 800 meters (0.5 miles) if fire is involved
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 112 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.