UN 3524 — Phosphorus pentafluoride, adsorbed
Placard: Toxic Gas. ERG Guide 173. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3524 is Phosphorus pentafluoride, adsorbed, a toxic corrosive adsorbed PF5 gas assigned to ERG Guide 173. Moisture can form HF and phosphorus oxyacid fumes.
Hazard overview: TOXIC and CORROSIVE phosphorus pentafluoride gas adsorbed on a porous solid; inhalation may be fatal. Reacts vigorously with water or moist air to form hydrogen fluoride and phosphorus oxyacid fumes. HF-containing products can cause deep tissue burns and serious respiratory injury.
Response guidance: For UN 3524, isolate downwind/low areas, treat as a life-threatening gas release and use Level A/SCBA for entry. Verify exact gas with shipping papers and ERG 173.
Firefighter training notes: Training for UN 3524 should emphasize toxic-gas recognition, Zone A isolation, Level A/SCBA entry, air monitoring, source-control limits and decontamination. Use ERG 173, SDS and local SOP.
Regulatory context: Phosphorus pentafluoride, adsorbed is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, gas identity and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Phosphorus pentafluoride, adsorbed should be stored in secured compatible adsorbed-gas packages away from heat, impact, corrosion, moisture where incompatible and unauthorized access, with ventilation and emergency planning.
UN 3524 Quick Details
Common Hazards of UN 3524
- TOXIC and CORROSIVE phosphorus pentafluoride gas adsorbed on a porous solid; inhalation may be fatal.
- Reacts vigorously with water or moist air to form hydrogen fluoride and phosphorus oxyacid fumes.
- HF-containing products can cause deep tissue burns and serious respiratory injury.
- Released gas is heavier than air and can collect in low or confined areas.
- Non-flammable gas, but fire may release toxic/corrosive fluorinated products.
- Runoff or vapor-control water may be fluoride-contaminated and corrosive.
- Container heating may release gas or rupture the package.
Chemical Identity & Physical Properties
Colorless gas with a pungent, irritating odor. Shipped adsorbed on inert solid material. Fumes in moist air.
| Also known as | Phosphorus(V) fluoridePentafluorophosphorusPF5Phosphoric fluoride |
| CAS Number | 7647-19-0 |
| Appearance | Colorless gas with a pungent, irritating odor. Shipped adsorbed on inert solid material. Fumes in moist air. |
| Flash Point | Not applicable (nonflammable gas) |
| Boiling Point | -84.6C (-120.3F) |
| Vapor Density | 4.3 (heavier than air) |
| Water Reactivity | Reacts vigorously with water producing toxic and corrosive hydrogen fluoride (hydrofluoric acid) fumes |
Fireground Response Guidance — UN 3524
Extinguishing Media
PPE Requirements
Use Level A fully encapsulating chemical protective clothing with positive-pressure SCBA for entry. Zone A toxic gas requires maximum respiratory and skin protection.
Isolation & Evacuation
First Actions for a UN 3524 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 avoid low or poorly ventilated areas unless monitoring shows they are safe.
- Treat the release as a life-threatening inhalation hazard until the gas is identified and monitored.
- Do not handle leaking cylinders, adsorbed-gas packages or damaged gas articles without proper training and PPE.
- Ventilate only after monitoring and only if properly trained and equipped.
- Use ERG Guide 173, shipping papers, markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3524 — Phosphorus pentafluoride, adsorbedUse 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.