☣️ UN 1439 • CLASS 5
UN 1439 — Ammonium dichromate
Placard: Oxidizer. ERG Guide 141. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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.
Ammonium dichromate is an orange to red-orange crystalline solid that is used in various applications, including as a precursor to chromium oxide.
Hazard overview: Ammonium dichromate can accelerate burning when involved in a fire and may explode from heat or contamination. It can also release heat when dissolved in water.
Response guidance: In the event of a fire, use water spray for cooling only and do not use foam or CO2 on bulk material. For small fires, use dry sand.
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UN 1439 Quick Details
UN 1439
Product name: Ammonium dichromate
DOT Class: 5
Placard type: Oxidizer
ERG Guide: 141 (check current ERG)
Initial isolation: ERG 141: isolate spill 25-50m all directions; large spill isolate 100m, evacuate 300m downwind if fire
Common Hazards of UN 1439
- These substances will accelerate burning when involved in a fire.
- May explode from heat or contamination.
- Some may burn rapidly.
- Some will react explosively with hydrocarbons (fuels).
- May ignite combustibles (wood, paper, oil, clothing, etc.).
- Containers may explode when heated.
- Runoff may create fire or explosion hazard.
- Toxic by ingestion.
Chemical Identity & Physical Properties
Ammonium dichromate is an orange to red-orange crystalline solid with no distinct odor.
| Also known as | Ammonium bichromateDiammonium dichromateChromic acid diammonium saltAmmonium chromate(VI) |
| CAS Number | 7789-09-5 |
| Appearance | Orange to red-orange crystalline solid with no distinct odor. Exists as dense crystals at room temperature. |
| Flash Point | Not applicable (oxidizing solid) |
| Boiling Point | Not applicable (decomposes at 170-180C/338-356F before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water; exothermic dissolution but no violent reaction. Avoid contamination with organics. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1439
Extinguishing Media
Water spray for cooling only. Do not use foam or CO2 on bulk material. Dry sand for small fires.
PPE Requirements
⚠️ Level B minimum with SCBA required. Full body protection due to carcinogenic chromium(VI) exposure risk.
Level B minimum with SCBA required. Full body protection due to carcinogenic chromium(VI) exposure risk.
Isolation & Evacuation
ERG 141: isolate spill 25-50m all directions; large spill isolate 100m, evacuate 300m downwind if fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 141).
First Actions for a UN 1439 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- Consider initial downwind evacuation for at least 100 meters (330 feet).
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UN 1439 — Ammonium dichromateHAZMAT RADIO NOTE — UN 1439
Product: Ammonium dichromate
Class 5 / Oxidizer / ERG 141
PPE: Level B minimum with SCBA required. Full body protection due to carcinogenic chromium(VI) exposure risk.
ISOLATION: ERG 141: isolate spill 25-50m all directions; large spill isolate 100m, evacuate 300m downwind if fire
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 1439 — Ammonium dichromate
Class: 5 | Placard: Oxidizer | ERG Guide: 141
Appearance: Orange to red-orange crystalline solid with no distinct odor. Exists as dense crystals at room temperature.
Water Reactivity: Soluble in water; exothermic dissolution but no violent reaction. Avoid contamination with organics.
Extinguishing: Water spray for cooling only. Do not use foam or CO2 on bulk material. Dry sand for small fires.
PPE: Level B minimum with SCBA required. Full body protection due to carcinogenic chromium(VI) exposure risk.
Isolation: ERG 141: isolate spill 25-50m all directions; large spill isolate 100m, evacuate 300m downwind if fire
— Key Hazards —
• These substances will accelerate burning when involved in a fire.
• May explode from heat or contamination.
• Some may burn rapidly.
— First Actions —
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/ammonium-dichromate-un-1439 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1439 Ammonium dichromate Cls5 ERG141 | allfirefighter.com/hazmat/un/ammonium-dichromate-un-1439SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/ammonium-dichromate-un-1439
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Frequently Asked Questions about UN 1439
Yes, UN 1439 Ammonium dichromate may explode from heat or contamination.
No, do not use foam or CO2 on bulk material.
Level B minimum with SCBA required. Full body protection due to carcinogenic chromium(VI) exposure risk.
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.