UN 2455 — Methyl nitrite
Placard: Flammable Gas. ERG Guide 116. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2455 is Methyl nitrite, an extremely flammable liquefied gas assigned to ERG Guide 116. Instability, flashback and NOx decomposition products require caution.
Hazard overview: EXTREMELY FLAMMABLE gas; forms explosive mixtures with air and may ignite readily. May be unstable under heat, contamination or pressure conditions. Gas can travel to ignition sources and flash back.
Response guidance: For UN 2455, isolate the leak, eliminate ignition sources and use SCBA. Stop gas flow only if safe; do not extinguish a leaking gas fire unless flow can be stopped, and cool cylinders from protection using ERG 116.
Firefighter training notes: Training for UN 2455 should emphasize flammable gas behavior, source isolation, no-extinguishment-until-flow-stopped tactics, cylinder cooling, flashback and frostbite. Use ERG 116, SDS and local SOP.
Regulatory context: Methyl nitrite is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Methyl nitrite cylinders should be secured in a cool, ventilated gas-storage area away from heat, physical damage and incompatible materials. Provide leak detection, ventilation and emergency planning according to SDS and local code.
UN 2455 Quick Details
Common Hazards of UN 2455
- EXTREMELY FLAMMABLE gas; forms explosive mixtures with air and may ignite readily.
- May be unstable under heat, contamination or pressure conditions.
- Gas can travel to ignition sources and flash back.
- Liquefied gas contact may cause frostbite.
- Heating or decomposition may release nitrogen oxides and other toxic gases.
- Cylinders exposed to fire may rupture or rocket.
- Do not extinguish a leaking gas fire unless the gas flow can be stopped safely.
Chemical Identity & Physical Properties
Colorless to pale yellow gas with a sweet, ethereal odor. Exists as a gas at room temperature and is shipped as a liquefied compressed gas.
| Also known as | Nitrous acid methyl esterMethyl ester of nitrous acidMethylester kyseliny dusicite |
| CAS Number | 624-91-9 |
| Appearance | Colorless to pale yellow gas with a sweet, ethereal odor. Exists as a gas at room temperature and is shipped as a liquefied compressed gas. |
| Flash Point | Not applicable (gas, extremely flammable with wide flammable range) |
| Boiling Point | -12C (10F) |
| Vapor Density | 2.1 (heavier than air) |
| Water Reactivity | Decomposes slowly in water, producing methanol and nitrous acid; no violent reaction |
Fireground Response Guidance — UN 2455
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for gas, fire or confined-space exposure. Wear flame/chemical protection as appropriate and insulated gloves for liquefied-gas frostbite risk.
Isolation & Evacuation
First Actions for a UN 2455 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 safe and do not extinguish a leaking gas fire unless flow can be stopped.
- Avoid breathing vapor, dust, gas, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 116, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2455 — Methyl nitriteUse 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.