UN 3396 — Organometallic substance, solid, water-reactive, flammable
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3396 is Organometallic substance, solid, water-reactive, flammable, a broad organometallic entry assigned to ERG Guide 138. The main concern is water-reactive gas generation plus flammable behavior; exact compound/SDS verification is critical.
Hazard overview: WATER-REACTIVE and FLAMMABLE organometallic solid; moisture can release flammable gases and heat. May ignite on contact with water, moist air, heat, sparks or flames. If solvent is present, vapors may travel to ignition sources and flash back.
Response guidance: For UN 3396, isolate the area, keep all water/moisture away and use SCBA from a protected position. Use compatible dry media only and watch for re-ignition under ERG 138.
Firefighter training notes: Training for UN 3396 should emphasize pyrophoric/water-reactive behavior, dry-media tactics, re-ignition checks, moisture exclusion, SCBA use and runoff/debris control. Use ERG 138, SDS and local SOP.
Regulatory context: Organometallic substance, solid, water-reactive, flammable is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Organometallic substance, solid, water-reactive, flammable should be stored dry in compatible sealed containers under inert gas or approved protective liquid where required, away from water, moisture, air, heat, ignition sources and oxidizers.
UN 3396 Quick Details
Common Hazards of UN 3396
- WATER-REACTIVE and FLAMMABLE organometallic solid; moisture can release flammable gases and heat.
- May ignite on contact with water, moist air, heat, sparks or flames.
- If solvent is present, vapors may travel to ignition sources and flash back.
- Water, foam, CO2 and halogenated agents can worsen reaction or spread burning material.
- May re-ignite after apparent extinguishment.
- Fire may produce toxic metal oxide fumes, carbon monoxide and irritating organic smoke.
- Exact compound, solvent and package condition must be verified from SDS and shipping papers.
Chemical Identity & Physical Properties
Solid materials varying in color from white to gray or metallic appearance, typically odorless or with slight metallic odor. Physical state is solid at room temperature and may be powdered, crystalline, or in chunk form.
| Also known as | Organometallic compoundsMetal-organic solidsWater-reactive organometallic materialsPyrophoric organometallic substances |
| Appearance | Solid materials varying in color from white to gray or metallic appearance, typically odorless or with slight metallic odor. Physical state is solid at room temperature and may be powdered, crystalline, or in chunk form. |
| Flash Point | Not applicable (spontaneously combustible on contact with water or moist air) |
| Boiling Point | Variable depending on specific compound; most decompose before boiling |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts violently with water producing flammable gases (often hydrogen or metal hydrides); may ignite spontaneously. DO NOT USE WATER. |
Fireground Response Guidance — UN 3396
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA with fire/chemical protection and distance from reactive material. Level A or B may be needed for unknown compound, vapor, splash or residue contact.
Isolation & Evacuation
First Actions for a UN 3396 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Exclude water, moisture, foam and incompatible extinguishing media.
- Avoid disturbing residue because pyrophoric or water-reactive material may re-ignite.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 138, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3396 — Organometallic substance, solid, water-rUse 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.