☣️ UN 2985 • CLASS 3
UN 2985 — Chlorosilanes, flammable, corrosive, n.o.s.
Placard: Flammable. ERG Guide 155. 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 2985 Quick Details
UN 2985
Product name: Chlorosilanes, flammable, corrosive, n.o.s.
DOT Class: 3
Placard type: Flammable
ERG Guide: 155 (check current ERG)
Initial isolation: ERG 155: Isolate spill 50m all directions. Evacuate 800m downwind if large spill. Increase distances at night or if tank/rail car involved in fire.
Common Hazards of UN 2985
- HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
- Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
Chemical Identity & Physical Properties
| Also known as | Chlorosilanes n.o.s.Flammable chlorosilanesCorrosive chlorosilanesOrganosilicon chlorides |
| Appearance | Typically colorless to pale yellow liquids with pungent, acrid odor. Fuming liquid that releases corrosive vapors on contact with moisture. |
| Flash Point | -18C to 10C (0F to 50F) depending on specific chlorosilane |
| Boiling Point | 30C to 150C (86F to 302F) depending on specific chlorosilane |
| Vapor Density | 3-6 (heavier than air, will collect in low areas) |
| Water Reactivity | Reacts violently with water, generating heat and corrosive hydrogen chloride gas. Do not use water directly on material. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2985
Extinguishing Media
Dry chemical, CO2, or dry sand only. Do not use water or foam directly on liquid.
PPE Requirements
⚠️ Level B minimum with SCBA required. Wear full chemical protective clothing and gloves resistant to corrosive vapors.
Isolation & Evacuation
ERG 155: Isolate spill 50m all directions. Evacuate 800m downwind if large spill. Increase distances at night or if tank/rail car involved in fire.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 155).
First Actions for a UN 2985 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 2985 — Chlorosilanes, flammable, corrosive, n.oHAZMAT RADIO NOTE — UN 2985
Product: Chlorosilanes, flammable, corrosive, n.o.s.
Class 3 / Flammable / ERG 155
PPE: Level B minimum with SCBA required. Wear full chemical protective clothing and gloves resistant to corrosive vapors.
ISOLATION: ERG 155: Isolate spill 50m all directions. Evacuate 800m downwind if large spill. Increase distances at night or if tank/rail car involved in fire.
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 2985 — Chlorosilanes, flammable, corrosive, n.o.s.
Class: 3 | Placard: Flammable | ERG Guide: 155
Appearance: Typically colorless to pale yellow liquids with pungent, acrid odor. Fuming liquid that releases corrosive vapors on contact with moisture.
Water Reactivity: Reacts violently with water, generating heat and corrosive hydrogen chloride gas. Do not use water directly on material.
Extinguishing: Dry chemical, CO2, or dry sand only. Do not use water or foam directly on liquid.
PPE: Level B minimum with SCBA required. Wear full chemical protective clothing and gloves resistant to corrosive vapors.
Isolation: ERG 155: Isolate spill 50m all directions. Evacuate 800m downwind if large spill. Increase distances at night or if tank/rail car involved in fire.
— Key Hazards —
• HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
• Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
• Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
— 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/2985 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2985 Chlorosilanes, flammable, corrosive, n.o.s. Cls3 ERG155 | allfirefighter.com/hazmat/un/2985SMS / 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/2985
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Frequently Asked Questions about UN 2985
HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapors may travel to source of ignition and flash back. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
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. Wear full chemical protective clothing and gloves resistant to corrosive vapors.
Water reactivity: Reacts violently with water, generating heat and corrosive hydrogen chloride gas. Do not use water directly on material.. Recommended extinguishing: Dry chemical, CO2, or dry sand only. Do not use water or foam directly on liquid..
ERG Guide 155 recommendation: ERG 155: Isolate spill 50m all directions. Evacuate 800m downwind if large spill. Increase distances at night or if tank/rail car involved in fire.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 155 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.