☣️ UN 2805 • CLASS 4
UN 2805 — Lithium hydride, fused solid
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
UN 2805 At a Glance
UN 2805 (Lithium hydride, fused solid) is listed as DOT Class 4 Dangerous When Wet and is assigned to ERG Guide 138. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
Lithium hydride, fused solid is a dangerous-when-wet hydride. Water, foam, humidity or wet tools can generate flammable hydrogen and heat.
Hazard overview: The critical hazard is water reactivity. Hydrogen generation can lead to ignition or explosion, and partially extinguished material can re-ignite if moisture remains.
Response guidance: Keep water away, isolate the area and use dry chemical, dry sand, dry graphite or other approved dry media. Do not apply foam or water unless a specialist directs it for the specific incident.
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UN 2805 Quick Details
UN 2805
Product name: Lithium hydride, fused solid
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: Isolate spill 100m all directions. If fire or water contact, isolate 800m and evacuate 1600m downwind.
Common Hazards of UN 2805
- Lithium hydride reacts violently with water and moisture to release hydrogen gas and heat.
- Hydrogen generated by reaction may ignite or explode.
- Material may ignite on contact with moist air or after firefighting water exposure.
- Dust or decomposition products can injure eyes, skin and the respiratory tract.
- Fires may re-ignite after apparent extinguishment if material remains wet or hot.
- Runoff or wet absorbent can create a delayed fire or explosion hazard.
- Containers may rupture when heated or contaminated with water.
Chemical Identity & Physical Properties
It is usually a gray to white solid or powder. The material is hygroscopic and must be protected from moisture throughout response and cleanup.
| Also known as | Lithium hydride fusedLithium monohydrideLiHLithium hydride solid |
| CAS Number | 7580-67-8 |
| Appearance | Gray to white crystalline solid or powder. Odorless. Hygroscopic material that absorbs moisture from air. |
| Flash Point | Not applicable (reacts with water to produce flammable hydrogen gas) |
| Boiling Point | Not applicable (decomposes above 850C/1562F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously. Do not use water. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2805
Extinguishing Media
Dry chemical, dry sand, dry graphite powder, or soda ash. NO water-based agents.
PPE Requirements
⚠️ Level B minimum with SCBA required. Full face protection, chemical-resistant suit. Avoid any moisture contact.
Use SCBA with chemical-resistant protective clothing and full face protection. Keep PPE, tools and absorbents dry and compatible with hydrides.
Isolation & Evacuation
ERG 138: Isolate spill 100m all directions. If fire or water contact, isolate 800m and evacuate 1600m downwind.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 2805 Incident
- Call 911 and the emergency response number shown on the shipping papers or container documents.
- Keep unauthorized personnel away and isolate the area before approaching.
- Stay upwind, uphill and upstream; keep all water sources away from the material.
- Avoid breathing reaction gases, dust or smoke and avoid all skin and eye contact.
- Do not touch damaged containers or spilled material without dry-compatible PPE and tools.
- Do not apply water or foam unless a qualified hazmat specialist directs it for a specific product.
- Use ERG guidance, SDS, shipping papers and monitoring to confirm isolation and evacuation distances.
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📋 Copy & Share Field Card
UN 2805 — Lithium hydride, fused solidHAZMAT RADIO NOTE — UN 2805
Product: Lithium hydride, fused solid
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required. Full face protection, chemical-resistant suit. Avoid any moisture contact.
ISOLATION: ERG 138: Isolate spill 100m all directions. If fire or water contact, isolate 800m and evacuate 1600m downwind.
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2805 — Lithium hydride, fused solid
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Gray to white crystalline solid or powder. Odorless. Hygroscopic material that absorbs moisture from air.
Water Reactivity: Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously. Do not use water.
Extinguishing: Dry chemical, dry sand, dry graphite powder, or soda ash. NO water-based agents.
PPE: Level B minimum with SCBA required. Full face protection, chemical-resistant suit. Avoid any moisture contact.
Isolation: ERG 138: Isolate spill 100m all directions. If fire or water contact, isolate 800m and evacuate 1600m downwind.
— Key Hazards —
• Lithium hydride reacts violently with water and moisture to release hydrogen gas and heat.
• Hydrogen generated by reaction may ignite or explode.
• Material may ignite on contact with moist air or after firefighting water exposure.
— First Actions —
• Call 911 and the emergency response number shown on the shipping papers or container documents.
• Keep unauthorized personnel away and isolate the area before approaching.
• Stay upwind, uphill and upstream; keep all water sources away from the material.
• Avoid breathing reaction gases, dust or smoke and avoid all skin and eye contact.
SOURCE: allfirefighter.com/hazmat/un/lithium-hydride-fused-solid-un-2805 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN2805 Lithium hydride, fused solid Cls4 ERG138 | allfirefighter.com/hazmat/un/lithium-hydride-fused-solid-un-2805SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/lithium-hydride-fused-solid-un-2805
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Frequently Asked Questions about UN 2805
It can react violently, releasing heat and flammable hydrogen gas.
No. Foam contains water and can make the reaction worse.
Dry chemical, dry sand, dry graphite or other approved dry media should be considered first.
Residual hydride can keep reacting with moisture and produce hydrogen after visible flames are out.
Keep the material dry, isolate the area and prevent water or wet runoff from contacting the spill.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.