☣️ UN 1391 • CLASS 4
Alkaline earth metal dispersion
Placard: Dangerous When Wet. 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.
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Quick details
UN 1391
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: Initial isolation 50m in all directions. Protect from water sources. If fire involves material, isolate 800m and consider evacuation in downwind direction.
Chemical & Response Details
| Also known as | Alkaline earth metal dispersionGroup 2 metal dispersionCalcium dispersionMagnesium dispersionBarium dispersion |
| Appearance | Metallic dispersion or suspension, typically grayish to silver-white powder or particles suspended in mineral oil or other inert carrier liquid. May appear as a paste or slurry. |
| Flash Point | Not applicable (water-reactive solid/dispersion) |
| Boiling Point | Not applicable (decomposes on heating or water contact) |
| Vapor Density | Not applicable (solid dispersion) |
| Water Reactivity | Reacts vigorously to violently with water, producing flammable hydrogen gas and heat. May ignite spontaneously on contact with water or moist air. |
| Extinguishing | Dry sand, dry chemical, soda ash, graphite powder. DO NOT use water, foam, CO2, or halogenated agents. |
| PPE | ⚠️ Level B minimum with SCBA required. Chemical-resistant suit, gloves, and boots. Eye protection mandatory. Avoid all contact with water or moisture. |
| Isolation | ERG 138: Initial isolation 50m in all directions. Protect from water sources. If fire involves material, isolate 800m and consider evacuation in downwind direction. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Produce flammable gases on contact with water.
- May ignite on contact with water or moist air.
- Some react vigorously or explosively on contact with water.
- May be ignited by heat, sparks or flames.
- May re-ignite after fire is extinguished.
- Some are transported in highly flammable liquids.
- Runoff may create fire or explosion hazard.
- Inhalation or contact with vapors, substance or decomposition products may cause severe injury or
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- Consider initial downwind evacuation for at least 300 meters (1000 feet).
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UN 1391 — Alkaline earth metal dispersion HAZMAT RADIO NOTE — UN 1391
Product: Alkaline earth metal dispersion
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required. Chemical-resistant suit, gloves, and boots. Eye protection mandatory. Avoid all contact with water or moisture.
ISOLATION: ERG 138: Initial isolation 50m in all directions. Protect from water sources. If fire involves material, isolate 800m and consider evacuation in downwind direction.
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 1391 — Alkaline earth metal dispersion
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Metallic dispersion or suspension, typically grayish to silver-white powder or particles suspended in mineral oil or other inert carrier liquid. May appear as a paste or slurry.
Water Reactivity: Reacts vigorously to violently with water, producing flammable hydrogen gas and heat. May ignite spontaneously on contact with water or moist air.
Extinguishing: Dry sand, dry chemical, soda ash, graphite powder. DO NOT use water, foam, CO2, or halogenated agents.
PPE: Level B minimum with SCBA required. Chemical-resistant suit, gloves, and boots. Eye protection mandatory. Avoid all contact with water or moisture.
Isolation: ERG 138: Initial isolation 50m in all directions. Protect from water sources. If fire involves material, isolate 800m and consider evacuation in downwind direction.
— Key Hazards —
• Produce flammable gases on contact with water.
• May ignite on contact with water or moist air.
• Some react vigorously or explosively on contact with water.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/1391 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1391 Alkaline earth metal dispersion Cls4 ERG138 | allfirefighter.com/hazmat/un/1391SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/1391
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FAQ
Produce flammable gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Runoff may create fire or explosion hazard. Inhalation or contact with vapors, substance or decomposition products may cause severe injury or
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum with SCBA required. Chemical-resistant suit, gloves, and boots. Eye protection mandatory. Avoid all contact with water or moisture.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 138 and your department SOP/SOG for incident-specific protective actions.
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.