UN 1051 — Hydrogen cyanide, stabilized
Placard: Poison. ERG Guide 117. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1051 is Hydrogen cyanide, stabilized, an extremely toxic flammable material assigned to ERG Guide 117. Rapid inhalation toxicity and skin absorption require strict control.
Hazard overview: EXTREMELY TOXIC and FLAMMABLE liquid/vapor; inhalation, ingestion or skin absorption may be fatal. Vapors may form explosive mixtures with air and can ignite from heat, sparks or flames. Vapor is slightly lighter than air but can behave unpredictably in wind, temperature gradients or confined spaces.
Response guidance: For UN 1051, isolate immediately, eliminate ignition sources and avoid all skin/vapor exposure. Use Level A/SCBA where needed and contain cyanide runoff under ERG 117.
Firefighter training notes: Training for UN 1051 should emphasize rapid toxic exposure, skin absorption, antidote/medical coordination, Level A decisions, decontamination and runoff control. Use ERG 117, SDS and local SOP.
Regulatory context: Hydrogen cyanide, stabilized is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, package type and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Hydrogen cyanide, stabilized should be stored in approved tightly closed containers away from heat, ignition sources, acids, oxidizers and incompatible materials, with ventilation and cyanide emergency planning.
UN 1051 Quick Details
Common Hazards of UN 1051
- EXTREMELY TOXIC and FLAMMABLE liquid/vapor; inhalation, ingestion or skin absorption may be fatal.
- Vapors may form explosive mixtures with air and can ignite from heat, sparks or flames.
- Vapor is slightly lighter than air but can behave unpredictably in wind, temperature gradients or confined spaces.
- High concentrations may cause rapid collapse; odor is not a reliable warning.
- Contact with acids can increase release of toxic hydrogen cyanide vapor from cyanide-containing mixtures.
- Fire may produce nitrogen oxides and toxic smoke.
- Runoff may carry cyanide contamination and requires specialist control.
Chemical Identity & Physical Properties
Hydrogen cyanide, stabilized physical appearance should be verified from SDS, package labels and shipping papers.
| Also known as | HCNPrussic acidHydrocyanic acid |
| CAS Number | 74-90-8 |
| Flash Point | -17.8°C (0°F) |
| Boiling Point | 25.7°C (78°F) |
| Vapor Density | 0.9 |
Fireground Response Guidance — UN 1051
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing; Level A may be needed for unknown concentration, heavy vapor, splash or skin-absorption risk.
Isolation & Evacuation
First Actions for a UN 1051 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, gas, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 117, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 1051 — Hydrogen cyanide, stabilizedUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.