UN 2602 — Dichlorodifluoromethane and difluoroethane azeotropic mixture with approximately 74% dichlorodifluoromethane
Placard: Non-Flammable Gas. ERG Guide 126. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2602 is Dichlorodifluoromethane and difluoroethane azeotropic mixture with approximately 74% dichlorodifluoromethane, a non-flammable liquefied refrigerant mixture assigned to ERG Guide 126. Oxygen displacement, frostbite and cylinder pressure are key hazards.
Hazard overview: NON-FLAMMABLE liquefied gas mixture; pressure and asphyxiation hazards are primary. Heavy vapor can collect in low or confined areas and displace oxygen without warning. Contact with liquefied gas can cause frostbite or cold burns.
Response guidance: For UN 2602, isolate low areas, ventilate only after monitoring and check oxygen levels. Protect against frostbite, cool cylinders from a distance and verify decomposition hazards with SDS and ERG 126.
Firefighter training notes: Training for UN 2602 should emphasize asphyxiation, oxygen monitoring, low-area accumulation, frostbite, cylinder heating and toxic decomposition products in fire. Use ERG 126, SDS and local SOP.
Regulatory context: Dichlorodifluoromethane and difluoroethane azeotropic mixture with approximately 74% dichlorodifluoromethane 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: Dichlorodifluoromethane and difluoroethane azeotropic mixture with approximately 74% dichlorodifluoromethane cylinders should be secured in a cool, ventilated gas-storage area away from heat and physical damage. Provide leak detection, ventilation and emergency planning according to SDS and local code.
UN 2602 Quick Details
Common Hazards of UN 2602
- NON-FLAMMABLE liquefied gas mixture; pressure and asphyxiation hazards are primary.
- Heavy vapor can collect in low or confined areas and displace oxygen without warning.
- Contact with liquefied gas can cause frostbite or cold burns.
- Cylinders or containers exposed to fire may vent, rupture or rocket.
- Fire or hot surfaces may decompose the refrigerant mixture and produce toxic/corrosive halogen acid gases.
- Ventilation and oxygen monitoring are critical in enclosed areas.
- Exact blend behavior should be verified from cylinder markings, SDS and shipping papers.
Chemical Identity & Physical Properties
Colorless liquefied gas with a faint ether-like odor. Stored under pressure as a liquid. Heavier than air as a vapor.
| Also known as | R-500Refrigerant 500CFC-12/HFC-152a mixtureDichlorodifluoromethane/difluoroethane blendFreon 500 |
| Appearance | Colorless liquefied gas with a faint ether-like odor. Stored under pressure as a liquid. Heavier than air as a vapor. |
| Flash Point | Not applicable (non-flammable gas mixture) |
| Boiling Point | Approximately -33C (-28F) for the azeotropic mixture |
| Vapor Density | 4.3 (heavier than air) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 2602
Extinguishing Media
PPE Requirements
Use SCBA and oxygen monitoring in confined or oxygen-deficient areas. Wear face/eye protection and insulated gloves for liquefied gas or cold vapor contact.
Isolation & Evacuation
First Actions for a UN 2602 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.
- Treat the release as an oxygen-displacement and pressure hazard until monitoring proves otherwise.
- Do not touch leaking cylinders or liquefied gas without proper training and PPE.
- Ventilate confined spaces only after oxygen monitoring and only if properly trained and equipped.
- Use ERG Guide 126, SDS, cylinder markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2602 — Dichlorodifluoromethane and difluoroethaUse 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.