☣️ UN 3148 • CLASS 4
UN 3148 — Water-reactive liquid, n.o.s.
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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.
Advertisement
UN 3148 Quick Details
UN 3148
Product name: Water-reactive liquid, n.o.s.
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: Initial isolation 50m (150 ft) all directions; protect from water/moisture; if fire or spill is large, isolate 800m (0.5 mi) and consider evacuation in downwind direction
Common Hazards of UN 3148
- 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 liquid not otherwise specifiedDangerous when wet liquidClass 4.3 liquidUN3148 |
| Appearance | Variable appearance depending on specific substance; typically clear to colored liquid that reacts with water or moisture in air. May emit visible fumes or heat upon contact with moisture. |
| Flash Point | Variable, substance-dependent; many have low flash points below 23C (73F) |
| Boiling Point | Variable, substance-dependent; typically 50-200C (122-392F) range |
| Vapor Density | Variable, substance-dependent; typically heavier than air (>1) |
| Water Reactivity | Reacts vigorously to violently with water, producing flammable gases (often hydrogen or other flammable vapors); may ignite spontaneously on contact with water or moist air |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3148
Extinguishing Media
Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2 containing moisture
PPE Requirements
⚠️ Level B minimum with SCBA required; full chemical-resistant suit if splash hazard; keep all PPE dry; avoid any moisture contact
Isolation & Evacuation
ERG 138: Initial isolation 50m (150 ft) all directions; protect from water/moisture; if fire or spill is large, isolate 800m (0.5 mi) and consider evacuation in downwind direction
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 3148 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).
Advertisement
📋 Copy & Share Field Card
UN 3148 — Water-reactive liquid, n.o.s.HAZMAT RADIO NOTE — UN 3148
Product: Water-reactive liquid, n.o.s.
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required; full chemical-resistant suit if splash hazard; keep all PPE dry; avoid any moisture contact
ISOLATION: ERG 138: Initial isolation 50m (150 ft) all directions; protect from water/moisture; if fire or spill is large, isolate 800m (0.5 mi) 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 3148 — Water-reactive liquid, n.o.s.
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Variable appearance depending on specific substance; typically clear to colored liquid that reacts with water or moisture in air. May emit visible fumes or heat upon contact with moisture.
Water Reactivity: Reacts vigorously to violently with water, producing flammable gases (often hydrogen or other flammable vapors); may ignite spontaneously on contact with water or moist air
Extinguishing: Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2 containing moisture
PPE: Level B minimum with SCBA required; full chemical-resistant suit if splash hazard; keep all PPE dry; avoid any moisture contact
Isolation: ERG 138: Initial isolation 50m (150 ft) all directions; protect from water/moisture; if fire or spill is large, isolate 800m (0.5 mi) 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/3148 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3148 Water-reactive liquid, n.o.s. Cls4 ERG138 | allfirefighter.com/hazmat/un/3148SMS / 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/3148
Advertisement
Frequently Asked Questions about UN 3148
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 chemical-resistant suit if splash hazard; keep all PPE dry; avoid any moisture contact
Water reactivity: Reacts vigorously to violently with water, producing flammable gases (often hydrogen or other flammable vapors); may ignite spontaneously on contact with water or moist air. Recommended extinguishing: Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2 containing moisture.
ERG Guide 138 recommendation: ERG 138: Initial isolation 50m (150 ft) all directions; protect from water/moisture; if fire or spill is large, isolate 800m (0.5 mi) and consider evacuation in downwind direction
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.