UN 1417 — Lithium silicon
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1417 is Lithium silicon, a water-reactive metal or metal alloy assigned to ERG Guide 138. It can react violently with moisture to release hydrogen and heat, and some alkali metals may ignite or explode on contact.
Hazard overview: UN 1417 presents hydrogen generation, violent water reaction and metal fire hazards. Water, foam or CO2 may worsen the incident; use shipping papers, SDS and incident command to confirm compatible dry agents.
Response guidance: For a UN 1417 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 138. 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 1417 should emphasize dangerous-when-wet behavior, flammable hydrogen gas 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 138, SDS and hazmat SOP.
Regulatory context: Lithium silicon 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: Lithium silicon 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 1417 Quick Details
Common Hazards of UN 1417
- DANGEROUS WHEN WET; contact with water or moisture can release flammable hydrogen gas.
- 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.
Chemical Identity & Physical Properties
Gray to dark gray solid powder or granular material. Odorless or slight metallic odor. Stable when dry but reacts with moisture.
| Also known as | Lithium silicideSilicide of lithiumLi-Si alloyLithium-silicon compound |
| CAS Number | 12415-17-9 |
| Appearance | Gray to dark gray solid powder or granular material. Odorless or slight metallic odor. Stable when dry but reacts with moisture. |
| Flash Point | Not applicable (ignites spontaneously on contact with water or moist air) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously. Keep absolutely dry. |
Fireground Response Guidance — UN 1417
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for any suspected flammable hydrogen gas, 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 1417 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 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 138, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1417 — Lithium siliconUse 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.