UN 2548 — Chlorine pentafluoride
Placard: Toxic Gas. ERG Guide 124. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Chlorine pentafluoride is a toxic, corrosive oxidizing gas shipped as UN 2548. It can support combustion, attack tissues and react dangerously with moisture or fuels.
Hazard overview: The gas may be fatal if inhaled and can cause severe burns or frostbite on contact. As a strong oxidizer, it can ignite or violently react with many combustible materials.
Response guidance: Operate from upwind and avoid direct contact with leaking gas or liquefied gas. Evacuate as needed using ERG 124 and Table 1. Fire tactics should focus on life safety, cylinder protection from a distance and specialist hazmat control.
Firefighter training notes: Train hazmat teams on toxic oxidizing gas behavior, cylinder rupture risk and Level A entry decisions. Include downwind monitoring and low-area gas migration.
Regulatory context: UN 2548 is transported as Chlorine pentafluoride, Class 2 toxic gas/oxidizer. Protective action distances should be confirmed using ERG Table 1 and shipping papers.
Storage & handling: Store cylinders upright, secured, cool and dry, away from fuels, organics, reducing agents and moisture. Protect valves and segregate from incompatible gases.
UN 2548 Quick Details
Common Hazards of UN 2548
- Chlorine pentafluoride is a toxic, corrosive oxidizing gas and may be fatal if inhaled.
- It does not burn, but it strongly supports combustion and can ignite many materials.
- Contact with gas or liquefied gas can cause severe chemical burns and frostbite.
- Water or moisture can generate corrosive and toxic acidic fumes, including fluoride-containing acids.
- Cylinder heating can cause rupture or violent release.
- Vapors may be heavier than air and move into low or confined areas.
- Fire exposure can produce irritating, corrosive and toxic gases.
Chemical Identity & Physical Properties
Chlorine pentafluoride is a colorless to pale yellow gas that can be liquefied under pressure. Vapors are much heavier than air.
| Also known as | Chlorine(V) fluoridePentafluorochlorineClF5 |
| CAS Number | 13637-63-3 |
| Appearance | Colorless to pale yellow gas with a sweet, suffocating odor. Highly reactive and corrosive. Liquefies at -13°C (8.6°F). |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | -13°C (8.6°F) |
| Vapor Density | 4.4 (much heavier than air) |
| Water Reactivity | Reacts violently with water producing heat, toxic hydrofluoric acid and chlorine fumes. Do not use water directly on material. |
Fireground Response Guidance — UN 2548
Extinguishing Media
PPE Requirements
Level A fully encapsulating protection with positive-pressure SCBA is appropriate for unknown or high-concentration releases. Structural gear alone is not adequate for gas contact.
Isolation & Evacuation
First Actions for a UN 2548 Incident
- Call 911 and the emergency response number on the shipping papers.
- Keep unauthorized personnel away and isolate from a protected, upwind position.
- Stay upwind, uphill and upstream; avoid low areas where gas may collect.
- Avoid breathing gas; prevent skin, eye and frostbite contact.
- Do not touch cylinders, valves or damaged containers without Level A/SCBA protection.
- Ventilate confined spaces only by trained hazmat personnel with monitoring.
- Use ERG 124, Table 1, SDS and shipping papers for protective action distances.
📋 Copy & Share Field Card
UN 2548 — Chlorine pentafluorideUse 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.