☣️ UN 3133 • CLASS 4
UN 3133 — Water-reactive solid, oxidizing, n.o.s.
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.
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UN 3133 Quick Details
UN 3133
Product name: Water-reactive solid, oxidizing, n.o.s.
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: Isolate spill 25-50m; evacuate 800m downwind if fire; keep dry at all costs
Common Hazards of UN 3133
- 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
Chemical Identity & Physical Properties
| Also known as | Water-reactive oxidizing solidOxidizing solid, water-reactiveDangerous when wet oxidizer |
| Appearance | Typically a white to yellow crystalline or powdered solid. Odor varies depending on specific substance. May emit irritating or toxic fumes when exposed to moisture. |
| Flash Point | Not applicable (solid, but ignites on contact with water) |
| Boiling Point | Not applicable (decomposes or reacts before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts violently with water producing flammable gases 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 3133
Extinguishing Media
Dry sand, dry chemical powder, soda ash; NO WATER, NO FOAM
PPE Requirements
⚠️ Level A or B with SCBA required; full chemical-resistant suit; avoid moisture exposure
Isolation & Evacuation
ERG 138: Isolate spill 25-50m; evacuate 800m downwind if fire; keep dry at all costs
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 3133 Incident
- 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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📋 Copy & Share Field Card
UN 3133 — Water-reactive solid, oxidizing, n.o.s.HAZMAT RADIO NOTE — UN 3133
Product: Water-reactive solid, oxidizing, n.o.s.
Class 4 / Dangerous When Wet / ERG 138
PPE: Level A or B with SCBA required; full chemical-resistant suit; avoid moisture exposure
ISOLATION: ERG 138: Isolate spill 25-50m; evacuate 800m downwind if fire; keep dry at all costs
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 3133 — Water-reactive solid, oxidizing, n.o.s.
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Typically a white to yellow crystalline or powdered solid. Odor varies depending on specific substance. May emit irritating or toxic fumes when exposed to moisture.
Water Reactivity: Reacts violently with water producing flammable gases and heat; may ignite spontaneously. DO NOT USE WATER.
Extinguishing: Dry sand, dry chemical powder, soda ash; NO WATER, NO FOAM
PPE: Level A or B with SCBA required; full chemical-resistant suit; avoid moisture exposure
Isolation: ERG 138: Isolate spill 25-50m; evacuate 800m downwind if fire; keep dry at all costs
— 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/3133 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3133 Water-reactive solid, oxidizing, n.o.s. Cls4 ERG138 | allfirefighter.com/hazmat/un/3133SMS / 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/3133
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Frequently Asked Questions about UN 3133
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 A or B with SCBA required; full chemical-resistant suit; avoid moisture exposure
Water reactivity: Reacts violently with water producing flammable gases and heat; may ignite spontaneously. DO NOT USE WATER.. Recommended extinguishing: Dry sand, dry chemical powder, soda ash; NO WATER, NO FOAM.
ERG Guide 138 recommendation: ERG 138: Isolate spill 25-50m; evacuate 800m downwind if fire; keep dry at all costs
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.