☣️ UN 2471 • CLASS 6
UN 2471 — Osmium tetroxide
Placard: Toxic. ERG Guide 154. 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.
Osmium tetroxide is a pale yellow to yellow-green crystalline solid or colorless to pale yellow liquid that melts at 40°C. It has a pungent, chlorine-like acrid odor.
Hazard overview: TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury. Contact with molten substance may cause severe burns to skin and eyes.
Response guidance: Use water spray to reduce vapors, CO2, dry chemical to extinguish fires.
Advertisement
UN 2471 Quick Details
UN 2471
Product name: Osmium tetroxide
DOT Class: 6
Placard type: Toxic
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Isolate spill 25-50m all directions. For large spill, isolate 100m and consider evacuation 300m downwind. Vapors are extremely toxic.
Common Hazards of UN 2471
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
Pale yellow to yellow-green crystalline solid or colorless to pale yellow liquid (melts at 40°C). Pungent, chlorine-like acrid odor.
| Also known as | Osmic acidOsmium(VIII) oxideOsmic anhydrideOsmium oxide |
| CAS Number | 20816-12-0 |
| Appearance | Pale yellow to yellow-green crystalline solid or colorless to pale yellow liquid (melts at 40°C). Pungent, chlorine-like acrid odor. Highly volatile even at room temperature. |
| Flash Point | Not applicable (non-flammable oxidizer) |
| Boiling Point | 130°C (266°F) |
| Vapor Density | 8.8 (much heavier than air) |
| Water Reactivity | Soluble in water; reacts slowly to form osmic acid solution. No violent reaction. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2471
Extinguishing Media
Water spray to reduce vapors, CO2, dry chemical. Foam not typically required.
PPE Requirements
⚠️ Level A required for significant exposure; SCBA mandatory. Full face protection, impervious suit. Highly toxic by inhalation and skin absorption.
Level A required for significant exposure; SCBA mandatory. Full face protection, impervious suit.
Isolation & Evacuation
ERG 154: Isolate spill 25-50m all directions. For large spill, isolate 100m and consider evacuation 300m downwind. Vapors are extremely toxic.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 2471 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
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
Advertisement
📋 Copy & Share Field Card
UN 2471 — Osmium tetroxideHAZMAT RADIO NOTE — UN 2471
Product: Osmium tetroxide
Class 6 / Toxic / ERG 154
PPE: Level A required for significant exposure; SCBA mandatory. Full face protection, impervious suit. Highly toxic by inhalation and skin absorption.
ISOLATION: ERG 154: Isolate spill 25-50m all directions. For large spill, isolate 100m and consider evacuation 300m downwind. Vapors are extremely toxic.
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 2471 — Osmium tetroxide
Class: 6 | Placard: Toxic | ERG Guide: 154
Appearance: Pale yellow to yellow-green crystalline solid or colorless to pale yellow liquid (melts at 40°C). Pungent, chlorine-like acrid odor. Highly volatile even at room temperature.
Water Reactivity: Soluble in water; reacts slowly to form osmic acid solution. No violent reaction.
Extinguishing: Water spray to reduce vapors, CO2, dry chemical. Foam not typically required.
PPE: Level A required for significant exposure; SCBA mandatory. Full face protection, impervious suit. Highly toxic by inhalation and skin absorption.
Isolation: ERG 154: Isolate spill 25-50m all directions. For large spill, isolate 100m and consider evacuation 300m downwind. Vapors are extremely toxic.
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— 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/osmium-tetroxide-un-2471 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN2471 Osmium tetroxide Cls6 ERG154 | allfirefighter.com/hazmat/un/osmium-tetroxide-un-2471SMS / 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/osmium-tetroxide-un-2471
Advertisement
Frequently Asked Questions about UN 2471
Yes
Yes
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
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.