UN 2545 — Hafnium powder, dry
Placard: Spontaneously Combustible. ERG Guide 135. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Dry hafnium powder is a reactive metal powder shipped as UN 2545. Finely divided material can ignite in air or moist air and can be difficult to extinguish once burning.
Hazard overview: The key hazard is spontaneous ignition of dry metal powder. Moisture can increase heating and hydrogen generation, and inappropriate agents such as water, foam or CO2 may spread or intensify the fire.
Response guidance: Avoid disturbing the powder. Isolate the area, keep water away and use Class D dry powder, dry sand or another SDS-approved dry medium. Expect re-ignition and monitor the material after knockdown.
Firefighter training notes: Train crews on reactive metal fire recognition, dry media use and the risk of re-ignition. Emphasize that standard water or foam tactics may be unsafe.
Regulatory context: UN 2545 is transported as Hafnium powder, dry, Class 4 spontaneously combustible material. Verify package type and emergency response information before handling.
Storage & handling: Keep sealed, dry and away from moisture, oxidizers, acids, heat and ignition sources. Store to prevent powder release and physical damage.
UN 2545 Quick Details
Common Hazards of UN 2545
- Dry hafnium powder is a spontaneously combustible metal powder; fine material can ignite in air or moist air.
- Dust may burn intensely and may re-ignite after apparent extinguishment.
- Contact with water or moisture can generate heat and flammable hydrogen.
- Water, foam or CO2 can worsen a reactive metal fire.
- Fire may produce irritating metal oxide smoke.
- Containers may rupture when heated.
- Dispersed powder can create a flash fire or dust explosion risk near ignition sources.
Chemical Identity & Physical Properties
Hafnium powder is a gray to silver-gray metallic powder. Fine dry powder presents a much higher ignition risk than compact metal.
| Also known as | Hafnium metal powderHafnium dustHf powder |
| CAS Number | 7440-58-6 |
| Appearance | Gray to silver-gray metallic powder, odorless. Pyrophoric when finely divided. |
| Flash Point | Not applicable (spontaneously combustible metal powder) |
| Boiling Point | 4603C (8317F) |
| Vapor Density | Not applicable (solid metal) |
| Water Reactivity | Reacts with moisture/water, especially when finely divided, generating heat and potentially igniting |
Fireground Response Guidance — UN 2545
Extinguishing Media
PPE Requirements
Use SCBA for smoke or unknown atmosphere. Fire-resistant clothing and chemical/thermal protection are needed, with tactics appropriate for reactive metal fires.
Isolation & Evacuation
First Actions for a UN 2545 Incident
- Call 911 and the emergency response number on the shipping papers.
- Keep unauthorized personnel away and eliminate ignition sources without disturbing powder.
- Stay upwind, uphill and upstream of smoke, dust and runoff.
- Avoid breathing dust or smoke; prevent skin and eye contact.
- Do not touch or move damaged containers without reactive-metal fire PPE and specialist guidance.
- Keep water away from the material unless the incident commander and SDS confirm otherwise.
- Use ERG 135, SDS and shipping papers to select dry extinguishing media and isolation distances.
📋 Copy & Share Field Card
UN 2545 — Hafnium powder, dryUse 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.