UN 1408 — Ferrosilicon
Placard: Dangerous When Wet. ERG Guide 139. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1408 is Ferrosilicon, a dangerous-when-wet ferrosilicon material assigned to ERG Guide 139. Moisture may generate hydrogen and other hazardous gases, especially in fine, hot or impure material.
Hazard overview: UN 1408 presents water-reactive metal alloy, hydrogen/silane-type gas and dust hazards. Keep the material dry, avoid confined spaces and verify composition from SDS before choosing extinguishing or cleanup actions.
Response guidance: For a UN 1408 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 139. Establish incident command, isolate the area, stay upwind, keep water and foam away from the material unless command confirms compatibility, monitor for reaction gases where possible and use only compatible dry agents.
Firefighter training notes: Training for UN 1408 should emphasize dangerous-when-wet behavior, flammable hydrogen gas and, in some conditions, toxic silane/phosphine-type gases generation, dry-agent selection, moisture exclusion and safe standoff. Common errors include using water or foam directly, entering low areas without monitoring and underestimating re-ignition. Use ERG 139, SDS and hazmat SOP.
Regulatory context: Ferrosilicon 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 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: Ferrosilicon should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, acids, oxidizers, heat and ignition sources. Protect containers from impact, corrosion, air exposure where relevant and unauthorized access.
UN 1408 Quick Details
Common Hazards of UN 1408
- DANGEROUS WHEN WET; contact with water or moisture can release flammable hydrogen gas and, in some conditions, toxic silane/phosphine-type gases.
- May ignite on contact with water or moist air.
- Reaction with water may generate heat, pressure and violent spattering.
- May be ignited by heat, sparks or flames and may re-ignite after apparent extinguishment.
- Containers may rupture or explode when heated.
- Runoff or water application may spread contamination and increase gas generation.
- Avoid low, enclosed or poorly ventilated areas where reaction gases may accumulate.
- Fine material or impurities can increase toxic gas evolution; verify composition from SDS and shipping papers.
Chemical Identity & Physical Properties
Gray to dark gray metallic solid with a crystalline or granular appearance. Odorless. Exists as lumps, granules, or powder at room temperature.
| Also known as | Ferrosilicon alloyIron silicon alloySilicon ironFerrosilicium |
| CAS Number | 8049-17-0 |
| Appearance | Gray to dark gray metallic solid with a crystalline or granular appearance. Odorless. Exists as lumps, granules, or powder at room temperature. |
| Flash Point | Not applicable (reacts with moisture to produce flammable hydrogen gas) |
| Boiling Point | Not applicable (solid alloy, decomposes/reacts rather than boils) |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts with water or moisture to produce flammable hydrogen gas and silane; reaction intensifies with heat and finely divided material |
Fireground Response Guidance — UN 1408
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for any suspected flammable hydrogen gas and, in some conditions, toxic silane/phosphine-type gases, fire, vapor or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS and incident command; keep PPE and tools dry when working near the material.
Isolation & Evacuation
First Actions for a UN 1408 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 low areas where flammable hydrogen gas and, in some conditions, toxic silane/phosphine-type gases may collect.
- Do not touch spilled material or damaged containers unless properly trained and equipped.
- Keep water, foam and moisture away from the released material unless incident command confirms a compatible cooling or control use.
- 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 water contact, fire or gas generation is suspected.
- Use ERG Guide 139, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1408 — FerrosiliconUse 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.