UN 2517 — 1-Chloro-1,1-difluoroethane
Placard: Flammable Gas. ERG Guide 115. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2517 is 1-Chloro-1,1-difluoroethane, a flammable liquefied halogenated gas assigned to ERG Guide 115. Flashback, frostbite and cylinder rupture are key hazards.
Hazard overview: EXTREMELY FLAMMABLE liquefied gas; may ignite easily by heat, sparks or flames. Gas can form explosive mixtures with air and flash back from ignition sources. Vapors from liquefied gas are initially heavier than air and may spread along the ground.
Response guidance: For UN 2517, 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.
Firefighter training notes: Training for UN 2517 should emphasize flammable gas behavior, source isolation, no-extinguishment-until-flow-stopped tactics, cylinder cooling, frostbite and toxic decomposition products. Use ERG 115, SDS and local SOP.
Regulatory context: 1-Chloro-1,1-difluoroethane 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: 1-Chloro-1,1-difluoroethane 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 2517 Quick Details
Common Hazards of UN 2517
- EXTREMELY FLAMMABLE liquefied gas; may ignite easily by heat, sparks or flames.
- Gas can form explosive mixtures with air and flash back from ignition sources.
- Vapors from liquefied gas are initially heavier than air and may spread along the ground.
- Liquefied gas can cause frostbite and cold burns.
- Cylinders exposed to fire may vent, rupture or rocket.
- Fire or hot surfaces may produce hydrogen chloride, hydrogen fluoride and other toxic/corrosive decomposition gases.
- Do not extinguish a leaking gas fire unless the gas flow can be stopped safely.
Chemical Identity & Physical Properties
Colorless gas or liquefied compressed gas with a faint ethereal odor. Shipped as a liquefied gas under pressure.
| Also known as | HCFC-142bChlorodifluoroethaneFreon 142bR-142b1,1-Difluoro-1-chloroethane |
| CAS Number | 75-68-3 |
| Appearance | Colorless gas or liquefied compressed gas with a faint ethereal odor. Shipped as a liquefied gas under pressure. |
| Flash Point | -58C (-73F) |
| Boiling Point | -9C (16F) |
| Vapor Density | 3.4 (heavier than air) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 2517
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA, flame-resistant protection and remote operations where possible. Protect against liquefied-gas frostbite and toxic decomposition products.
Isolation & Evacuation
First Actions for a UN 2517 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind and keep people out of low or poorly ventilated areas.
- Eliminate ignition sources if safe and do not extinguish a leaking gas fire unless flow can be stopped.
- Do not touch leaking cylinders or liquefied gas without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 115, SDS, cylinder markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2517 — 1-Chloro-1,1-difluoroethaneUse 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.