☣️ UN 3135 • CLASS 4
Water-reactive solid, selfheating, n.o.s.
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 3135
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: isolate spill 25-50m all directions; if fire or tank/rail car involved, isolate 800m all directions and consider evacuation 800m downwind
Chemical & Response Details
| Also known as | Water-reactive solid self-heating NOSSelf-heating water-reactive solidClass 4.3 self-heating solidDangerous when wet self-heating material |
| Appearance | Solid material of varying color and form depending on specific substance. May emit visible fumes or heat when exposed to moisture. Physical state is solid at room temperature. |
| Flash Point | Not applicable (water-reactive solid) |
| Boiling Point | Not applicable (decomposes or reacts with water) |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts with water producing flammable gases; may ignite spontaneously on contact with water or moist air; some substances react violently or explosively |
| Extinguishing | Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2 |
| PPE | ⚠️ Level B minimum with SCBA required; full protective clothing; keep upwind; avoid all contact with water or moisture |
| Isolation | ERG 138: isolate spill 25-50m all directions; if fire or tank/rail car involved, isolate 800m all directions and consider evacuation 800m downwind |
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 3135 — Water-reactive solid, selfheating, n.o.s HAZMAT RADIO NOTE — UN 3135
Product: Water-reactive solid, selfheating, n.o.s.
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required; full protective clothing; keep upwind; avoid all contact with water or moisture
ISOLATION: ERG 138: isolate spill 25-50m all directions; if fire or tank/rail car involved, isolate 800m all directions and consider evacuation 800m 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 3135 — Water-reactive solid, selfheating, n.o.s.
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Solid material of varying color and form depending on specific substance. May emit visible fumes or heat when exposed to moisture. Physical state is solid at room temperature.
Water Reactivity: Reacts with water producing flammable gases; may ignite spontaneously on contact with water or moist air; some substances react violently or explosively
Extinguishing: Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2
PPE: Level B minimum with SCBA required; full protective clothing; keep upwind; avoid all contact with water or moisture
Isolation: ERG 138: isolate spill 25-50m all directions; if fire or tank/rail car involved, isolate 800m all directions and consider evacuation 800m downwind
— 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/3135 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3135 Water-reactive solid, selfheating, n.o.s. Cls4 ERG138 | allfirefighter.com/hazmat/un/3135SMS / 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/3135
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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; full protective clothing; keep upwind; 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.