UN 1029 — Dichlorofluoromethane
Placard: Non-Flammable Gas. ERG Guide 126. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1029 is Dichlorofluoromethane, a Class 2 flammable gas assigned to ERG Guide 126. It can ignite easily, form explosive mixtures with air and create cylinder rupture hazards when heated.
Hazard overview: UN 1029 presents flammable vapor, flashback and pressure-container hazards. Fire or heat can cause cylinders to vent or rupture, while released gas may migrate before ignition.
Response guidance: For a UN 1029 incident, responders should confirm the product using shipping papers, cylinder markings, SDS and ERG Guide 126. Establish incident command, isolate the area, stay upwind, eliminate ignition sources when safe, monitor for flammable gas and cool exposed containers from a protected position.
Firefighter training notes: Training for UN 1029 should emphasize flammable vapor behavior, flashback, low-area migration, cylinder heating and ignition control. Common errors include approaching through vapor, operating damaged valves, standing near relief devices or cylinder ends and underestimating explosion potential in confined spaces. Use ERG 126, gas monitoring and local SOP.
Regulatory context: Dichlorofluoromethane is regulated as a Class 2 hazardous material for transportation and emergency response purposes. Cylinder, workplace exposure, storage, reporting and environmental requirements may vary by product, quantity and jurisdiction. Responders should verify current requirements through shipping papers, SDS, cylinder markings, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Dichlorofluoromethane cylinders should be stored secured, upright where required, well ventilated and away from heat, ignition sources, oxidizers, incompatible gases and physical damage. Storage areas should control leaks, cylinder impact, unauthorized access and accumulation of gas in low or confined spaces.
UN 1029 Quick Details
Common Hazards of UN 1029
- EXTREMELY FLAMMABLE: will be easily ignited by heat, sparks or flames.
- Will form explosive mixtures with air.
- Vapors from liquefied gas may be heavier than air and spread along the ground.
- Vapors may travel to an ignition source and flash back.
- Cylinders or pressure containers may vent, rupture or rocket when heated.
- Liquefied gas contact may cause frostbite or cold burns.
- Released gas can create a wide flammable atmosphere around damaged cylinders, valves or piping.
Chemical Identity & Physical Properties
Colorless gas or liquid (under pressure) with a faint, ether-like odor. Shipped as a liquefied compressed gas.
| Also known as | R-21HCFC-21Freon 21FluorodichloromethaneDichloromonofluoromethane |
| CAS Number | 75-43-4 |
| Appearance | Colorless gas or liquid (under pressure) with a faint, ether-like odor. Shipped as a liquefied compressed gas. |
| Flash Point | Not applicable (gas) |
| Boiling Point | 9°C (48°F) |
| Vapor Density | 3.8 (heavier than air) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 1029
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for fire, leak, vapor cloud or confined-space operations. Structural firefighting gear may protect against fire conditions, but responders should maintain distance from heated cylinders and follow incident command and local SOP.
Isolation & Evacuation
First Actions for a UN 1029 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Do not touch damaged cylinders, tanks, valves or released material unless properly trained and equipped.
- Eliminate ignition sources if it is safe to do so.
- Many vapors from liquefied gas are heavier than air and may collect in low or confined areas.
- Isolate the spill or leak area for at least 100 meters (330 feet) in all directions.
- Consider initial evacuation for at least 800 meters (1/2 mile) for a large release, fire or heated container.
- Use ERG Guide 126, shipping papers, air monitoring and incident command to set protective actions.
📋 Copy & Share Field Card
UN 1029 — DichlorofluoromethaneUse 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.