☣️ UN 2988 • CLASS 4
UN 2988 — Chlorosilanes, water-reactive, flammable, corrosive, n.o.s.
Placard: Dangerous When Wet. ERG Guide 139. 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 2988 Quick Details
UN 2988
Product name: Chlorosilanes, water-reactive, flammable, corrosive, n.o.s.
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 139 (check current ERG)
Initial isolation: ERG 139: isolate 100m minimum all directions; evacuate 800m downwind if fire or major spill. Consider 1600m for large fires.
Common Hazards of UN 2988
- Produce flammable and toxic 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.
- Containers may explode when heated.
- Runoff may create fire or explosion hazard.
Chemical Identity & Physical Properties
| Also known as | Water-reactive chlorosilanesChlorosilane compounds n.o.s.Reactive silicon chloridesFlammable chlorosilanes |
| Appearance | Typically colorless to pale yellow liquids with pungent, acrid odor. Some may be fuming liquids that react with atmospheric moisture. |
| Flash Point | -18C to 15C (0F to 59F) depending on specific compound |
| Boiling Point | 32C to 135C (90F to 275F) depending on specific chlorosilane |
| Vapor Density | 3.5 to 5.9 (heavier than air, varies by compound) |
| Water Reactivity | Reacts violently with water producing heat, flammable hydrogen gas, and corrosive HCl fumes. Never use water directly. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2988
Extinguishing Media
Dry chemical, CO2, dry sand only. DO NOT use water, foam, or aqueous agents.
PPE Requirements
⚠️ Level A or B required; SCBA mandatory; full chemical-resistant suit. Corrosive vapor hazard requires respiratory and skin protection.
Isolation & Evacuation
ERG 139: isolate 100m minimum all directions; evacuate 800m downwind if fire or major spill. Consider 1600m for large fires.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 139).
First Actions for a UN 2988 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
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 2988 — Chlorosilanes, water-reactive, flammableHAZMAT RADIO NOTE — UN 2988
Product: Chlorosilanes, water-reactive, flammable, corrosive, n.o.s.
Class 4 / Dangerous When Wet / ERG 139
PPE: Level A or B required; SCBA mandatory; full chemical-resistant suit. Corrosive vapor hazard requires respiratory and skin protection.
ISOLATION: ERG 139: isolate 100m minimum all directions; evacuate 800m downwind if fire or major spill. Consider 1600m for large fires.
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 2988 — Chlorosilanes, water-reactive, flammable, corrosive, n.o.s.
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 139
Appearance: Typically colorless to pale yellow liquids with pungent, acrid odor. Some may be fuming liquids that react with atmospheric moisture.
Water Reactivity: Reacts violently with water producing heat, flammable hydrogen gas, and corrosive HCl fumes. Never use water directly.
Extinguishing: Dry chemical, CO2, dry sand only. DO NOT use water, foam, or aqueous agents.
PPE: Level A or B required; SCBA mandatory; full chemical-resistant suit. Corrosive vapor hazard requires respiratory and skin protection.
Isolation: ERG 139: isolate 100m minimum all directions; evacuate 800m downwind if fire or major spill. Consider 1600m for large fires.
— Key Hazards —
• Produce flammable and toxic 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/2988 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2988 Chlorosilanes, water-reactive, flammable, corrosive, n.o.s. Cls4 ERG139 | allfirefighter.com/hazmat/un/2988SMS / 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/2988
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Frequently Asked Questions about UN 2988
Produce flammable and toxic 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. Containers may explode when heated. Runoff may create fire or explosion hazard.
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 required; SCBA mandatory; full chemical-resistant suit. Corrosive vapor hazard requires respiratory and skin protection.
Water reactivity: Reacts violently with water producing heat, flammable hydrogen gas, and corrosive HCl fumes. Never use water directly.. Recommended extinguishing: Dry chemical, CO2, dry sand only. DO NOT use water, foam, or aqueous agents..
ERG Guide 139 recommendation: ERG 139: isolate 100m minimum all directions; evacuate 800m downwind if fire or major spill. Consider 1600m for large fires.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 139 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.