UN 2599 — Chlorotrifluoromethane and trifluoromethane azeotropic mixture with approximately 60% chlorotrifluoromethane
Placard: Non-Flammable Gas. ERG Guide 126. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2599 covers a chlorotrifluoromethane/trifluoromethane azeotropic refrigerant mixture. It is generally treated as a nonflammable liquefied gas, but confined-space and fire hazards remain serious.
Hazard overview: A release can displace oxygen and cause frostbite from cold liquid. Fire exposure can rupture cylinders and decompose fluorinated/chlorinated refrigerants into toxic acid gases.
Response guidance: Evacuate low or enclosed areas, monitor oxygen and cool fire-exposed cylinders from a protected position. Do not enter suspected decomposition atmospheres without SCBA and appropriate gas monitoring.
Firefighter training notes: Training should cover refrigerant asphyxiation, oxygen monitoring, cylinder cooling and acid-gas hazards from thermal decomposition. Avoid assuming nonflammable means low risk.
Regulatory context: UN 2599 is a Class 2.2 refrigerant gas mixture entry. Verify mixture composition, cylinder pressure and emergency contacts on shipping papers and SDS.
Storage & handling: Store cylinders secured, upright and away from heat. Keep in ventilated areas and protect valves and relief devices from damage.
UN 2599 Quick Details
Common Hazards of UN 2599
- Compressed liquefied refrigerant gas mixture; exact composition affects pressure and decomposition hazards.
- Vapor can displace oxygen and cause asphyxiation in confined or low areas.
- Contact with liquid can cause frostbite and cold burns.
- Cylinders may rupture or rocket when heated in a fire.
- Heating or fire may produce toxic and corrosive decomposition products such as hydrogen fluoride and hydrogen chloride.
- Gas may accumulate in poorly ventilated spaces without strong warning odor.
- Some equipment oil or contamination may create additional fire or decomposition hazards.
Chemical Identity & Physical Properties
This material is a compressed liquefied gas mixture. Released liquid rapidly vaporizes, creating cold vapor that can collect in low or poorly ventilated areas.
| Also known as | CFC-13/R-23 azeotropeR-503Refrigerant 503Chlorotrifluoromethane/Trifluoromethane mixture |
| Appearance | Colorless liquefied compressed gas with a faint ethereal odor. Stored under pressure in cylinders. Heavier than air as a gas. |
| Flash Point | Not applicable (non-flammable compressed gas) |
| Boiling Point | Approximately -88°C (-126°F) at atmospheric pressure |
| Vapor Density | 3.8 (heavier than air) |
| Water Reactivity | No violent reaction with water expected; cold liquid contact can freeze water and surfaces. |
Fireground Response Guidance — UN 2599
Extinguishing Media
PPE Requirements
Use SCBA for oxygen-deficient, fire or decomposition conditions. Protect against frostbite with face, hand and body protection when liquid contact is possible.
Isolation & Evacuation
First Actions for a UN 2599 Incident
- Call 911 and the emergency response number shown on shipping papers; confirm the material with ERG, SDS and container markings.
- Keep unauthorized personnel away and establish hot, warm and cold zones before entry.
- Stay upwind, uphill and upstream; avoid low areas where vapors, dust or runoff may collect.
- Avoid breathing vapors, dust, mist or decomposition products and prevent skin or eye contact.
- Do not touch damaged packages or containers unless properly trained and wearing suitable chemical PPE.
- Ventilate confined spaces only after atmospheric monitoring and only with trained, equipped personnel.
- Use ERG Guide 126, SDS, shipping papers and monitoring results for isolation, PPE and fire-control decisions.
📋 Copy & Share Field Card
UN 2599 — Chlorotrifluoromethane and trifluoromethUse 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.