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 At a Glance
UN 3524 (Phosphorus pentafluoride, adsorbed) is listed as DOT Class 2 Toxic Gas and is assigned to ERG Guide 173. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.