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 At a Glance
UN 2599 (Chlorotrifluoromethane and trifluoromethane azeotropic mixture with…) is listed as DOT Class 2 Non-Flammable Gas and is assigned to ERG Guide 126. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.