☣️ UN 1451 • CLASS 5
UN 1451 — Caesium nitrate
Placard: Oxidizer. ERG Guide 140. 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.
Caesium nitrate is a white or colorless crystalline solid with no odor. It is a hygroscopic powder or crystals at room temperature.
Hazard overview: These substances will accelerate burning when involved in a fire. Some may decompose explosively when heated or involved in a fire.
Response guidance: Isolate the spill/leak area 25m in all directions. If fire or large spill, isolate 800m and evacuate downwind.
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UN 1451 Quick Details
UN 1451
Product name: Caesium nitrate
DOT Class: 5
Placard type: Oxidizer
ERG Guide: 140 (check current ERG)
Initial isolation: ERG 140: isolate spill/leak area 25m in all directions; if fire or large spill isolate 800m and evacuate downwind
Common Hazards of UN 1451
- These substances will accelerate burning when involved in a fire.
- Some may decompose explosively when heated or involved in a fire.
- May explode from heat or contamination.
- 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.
- Inhalation, ingestion or contact (skin, eyes) with vapors or substance may cause severe injury, burns or
Chemical Identity & Physical Properties
White or colorless crystalline solid, odorless. Hygroscopic powder or crystals at room temperature.
| Also known as | Cesium nitrateNitric acid cesium saltCesium(I) nitrateCaesium mononitrate |
| CAS Number | 7789-18-6 |
| Appearance | White or colorless crystalline solid, odorless. Hygroscopic powder or crystals at room temperature. |
| Flash Point | Not applicable (oxidizing solid, non-flammable but supports combustion) |
| Boiling Point | Decomposes at 414C (777F) before boiling |
| Vapor Density | Not applicable (solid with negligible vapor pressure) |
| Water Reactivity | Soluble in water without hazardous reaction, but solution may be corrosive |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1451
Extinguishing Media
Water spray, dry chemical, CO2; avoid organic materials and combustibles near oxidizer
PPE Requirements
⚠️ Level C minimum for handling; SCBA and full protective clothing if fire involved or decomposition occurring
Level C minimum for handling; SCBA and full protective clothing if fire involved or decomposition occurring
Isolation & Evacuation
ERG 140: isolate spill/leak area 25m in all directions; if fire or large spill isolate 800m and evacuate downwind
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 140).
First Actions for a UN 1451 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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📋 Copy & Share Field Card
UN 1451 — Caesium nitrateHAZMAT RADIO NOTE — UN 1451
Product: Caesium nitrate
Class 5 / Oxidizer / ERG 140
PPE: Level C minimum for handling; SCBA and full protective clothing if fire involved or decomposition occurring
ISOLATION: ERG 140: isolate spill/leak area 25m in all directions; if fire or large spill isolate 800m and evacuate downwind
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 1451 — Caesium nitrate
Class: 5 | Placard: Oxidizer | ERG Guide: 140
Appearance: White or colorless crystalline solid, odorless. Hygroscopic powder or crystals at room temperature.
Water Reactivity: Soluble in water without hazardous reaction, but solution may be corrosive
Extinguishing: Water spray, dry chemical, CO2; avoid organic materials and combustibles near oxidizer
PPE: Level C minimum for handling; SCBA and full protective clothing if fire involved or decomposition occurring
Isolation: ERG 140: isolate spill/leak area 25m in all directions; if fire or large spill isolate 800m and evacuate downwind
— Key Hazards —
• These substances will accelerate burning when involved in a fire.
• Some may decompose explosively when heated or involved in a fire.
• May explode from heat or contamination.
— 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/caesium-nitrate-un-1451 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1451 Caesium nitrate Cls5 ERG140 | allfirefighter.com/hazmat/un/caesium-nitrate-un-1451SMS / 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/caesium-nitrate-un-1451
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Frequently Asked Questions about UN 1451
No, but it will accelerate burning when involved in a fire.
Use water spray, dry chemical, CO2 to extinguish fires.
Soluble in water without hazardous reaction, but solution may be corrosive
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.