UN 1749 — Chlorine trifluoride
Placard: Toxic Gas. ERG Guide 124. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1749 is Chlorine trifluoride, a Class 2 toxic gas assigned to ERG Guide 124. It is an extremely reactive oxidizing gas or liquefied gas that can cause fatal inhalation exposure, severe corrosive burns and violent reactions with many materials.
Hazard overview: UN 1749 is dangerous because it combines toxic gas, corrosive and powerful oxidizer hazards. It may not burn itself, but it can intensify fire, ignite ordinary combustibles and react violently with water, fuels, oils, organic materials and some metals.
Response guidance: For a UN 1749 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 124. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1749 should emphasize extreme oxidizer reactivity, water incompatibility, ordinary combustible ignition, heavy vapor behavior, evacuation decisions and specialist hazmat control. Use ERG 124, SDS and local SOP.
Regulatory context: Chlorine trifluoride is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Chlorine trifluoride should be stored in compatible pressure or corrosion-resistant containers under strict oxidizer/reactive-material controls, away from water, fuels, organics, reducing agents, metals where incompatible, heat and unauthorized access. Storage should follow SDS, facility hazmat engineering controls and emergency planning.
UN 1749 Quick Details
Common Hazards of UN 1749
- TOXIC and/or CORROSIVE; may be fatal if inhaled or absorbed through skin.
- Contact with gas or liquefied gas may cause severe burns, serious injury and/or frostbite.
- Substance does not burn but strongly supports combustion.
- Strong oxidizer; may react vigorously or explosively with fuels, water, organic materials, metals and other incompatible substances.
- May ignite combustibles such as wood, paper, oil, clothing and other ordinary materials.
- Fire or heat may produce irritating, corrosive and/or toxic gases.
- Vapors from liquefied gas are initially heavier than air and may spread along the ground into low or confined areas.
- Runoff from fire control or dilution water may be corrosive, toxic and environmentally hazardous.
Chemical Identity & Physical Properties
Colorless to pale greenish-yellow gas or liquid with a pungent, irritating odor. Highly reactive and corrosive. Liquefied under pressure.
| Also known as | ClF3Chlorine fluorideTrifluorochlorineChlorotrifluoride |
| CAS Number | 7790-91-2 |
| Appearance | Colorless to pale greenish-yellow gas or liquid with a pungent, irritating odor. Highly reactive and corrosive. Liquefied under pressure. |
| Flash Point | Not applicable (oxidizer, does not burn but supports combustion) |
| Boiling Point | 11.8°C (53.2°F) |
| Vapor Density | 3.14 (heavier than air) |
| Water Reactivity | Reacts violently with water, producing toxic and corrosive gases (HF, HCl). Do not use water for extinguishment. |
Fireground Response Guidance — UN 1749
Extinguishing Media
PPE Requirements
UN 1749 incidents may require fully encapsulating chemical protective clothing with positive-pressure SCBA for entry operations. PPE selection should be made by incident command using ERG 124, SDS, air monitoring, container condition and local hazmat SOP because chlorine trifluoride can attack skin, eyes, lungs and incompatible materials.
Isolation & Evacuation
First Actions for a UN 1749 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.
- Avoid breathing vapors, fumes, dust, mist or gas and avoid skin or eye contact.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if vapor, gas, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 124, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1749 — Chlorine trifluorideUse 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.