☣️ UN 1541 • CLASS 6
UN 1541 — Acetone cyanohydrin, stabilized
Placard: Toxic. ERG Guide 156. 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.
Acetone cyanohydrin is a highly toxic substance that requires special handling due to its reactivity with water and the release of hydrogen cyanide gas (HCN). It is typically stabilized with phosphoric acid to prevent decomposition.
Hazard overview: Acetone cyanohydrin is a highly toxic substance that will react with water releasing flammable, toxic, or corrosive gases and runoff. It is also a combustible material that may burn but does not ignite readily.
Response guidance: In the event of a spill, initially isolate the area 50m in all directions and evacuate the surrounding area. For fires, use alcohol-resistant foam, CO2, or dry chemical. Do not use water spray to cool containers, as it may cause a violent reaction and HCN release.
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UN 1541 Quick Details
UN 1541
Product name: Acetone cyanohydrin, stabilized
DOT Class: 6
Placard type: Toxic
ERG Guide: 156 (check current ERG)
Initial isolation: ERG 156: Initially isolate 50m in all directions; if tank/rail car involved in fire, isolate 800m in all directions and evacuate initial 800m downwind
Common Hazards of UN 1541
- Combustible material: may burn but does not ignite readily.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
- TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
Chemical Identity & Physical Properties
Acetone cyanohydrin is a colorless to straw-colored liquid with a faint almond-like odor.
| Also known as | 2-Hydroxy-2-methylpropanenitrile2-MethyllactonitrileACHCyanhydrin acetone2-Cyanopropan-2-ol |
| CAS Number | 75-86-5 |
| Appearance | Colorless to straw-colored liquid with a faint almond-like odor. Liquid at room temperature, typically stabilized with phosphoric acid to prevent decomposition. |
| Flash Point | 74°C (165°F) |
| Boiling Point | 95°C (203°F) - decomposes at higher temperatures |
| Vapor Density | 2.9 (heavier than air) |
| Water Reactivity | Reacts with water releasing hydrogen cyanide gas (HCN), a highly toxic flammable gas. Reaction accelerates with heat or alkaline conditions. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1541
Extinguishing Media
Alcohol-resistant foam, CO2, dry chemical. Water may cause violent reaction and HCN release - use water spray only to cool containers from distance.
PPE Requirements
⚠️ Level A minimum due to HCN hazard; SCBA with full face protection required; chemical-resistant suit; cyanide antidote kit on standby
Level A minimum due to HCN hazard; SCBA with full face protection required; chemical-resistant suit; cyanide antidote kit on standby.
Isolation & Evacuation
ERG 156: Initially isolate 50m in all directions; if tank/rail car involved in fire, isolate 800m in all directions and evacuate initial 800m downwind
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 156).
First Actions for a UN 1541 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
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📋 Copy & Share Field Card
UN 1541 — Acetone cyanohydrin, stabilizedHAZMAT RADIO NOTE — UN 1541
Product: Acetone cyanohydrin, stabilized
Class 6 / Toxic / ERG 156
PPE: Level A minimum due to HCN hazard; SCBA with full face protection required; chemical-resistant suit; cyanide antidote kit on standby
ISOLATION: ERG 156: Initially isolate 50m in all directions; if tank/rail car involved in fire, isolate 800m in all directions and evacuate initial 800m 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 1541 — Acetone cyanohydrin, stabilized
Class: 6 | Placard: Toxic | ERG Guide: 156
Appearance: Colorless to straw-colored liquid with a faint almond-like odor. Liquid at room temperature, typically stabilized with phosphoric acid to prevent decomposition.
Water Reactivity: Reacts with water releasing hydrogen cyanide gas (HCN), a highly toxic flammable gas. Reaction accelerates with heat or alkaline conditions.
Extinguishing: Alcohol-resistant foam, CO2, dry chemical. Water may cause violent reaction and HCN release - use water spray only to cool containers from distance.
PPE: Level A minimum due to HCN hazard; SCBA with full face protection required; chemical-resistant suit; cyanide antidote kit on standby
Isolation: ERG 156: Initially isolate 50m in all directions; if tank/rail car involved in fire, isolate 800m in all directions and evacuate initial 800m downwind
— Key Hazards —
• Combustible material: may burn but does not ignite readily.
• Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
• When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
— 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/1541 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1541 Acetone cyanohydrin, stabilized Cls6 ERG156 | allfirefighter.com/hazmat/un/1541SMS / 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/acetone-cyanohydrin-stabilized-un-1541
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Frequently Asked Questions about UN 1541
Yes, UN 1541 Acetone cyanohydrin is a highly toxic substance that will react with water releasing flammable, toxic, or corrosive gases and runoff.
UN 1541 Acetone cyanohydrin will react with water releasing hydrogen cyanide gas (HCN), a highly toxic flammable gas.
Initially isolate the spill area 50m in all directions and evacuate the surrounding area.
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.