☣️ UN 2189 • CLASS 2
UN 2189 — Dichlorosilane
Placard: Toxic Gas. ERG Guide 119. 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 2189 Quick Details
UN 2189
Product name: Dichlorosilane
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 119 (check current ERG)
Initial isolation: ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/rail car involved in fire. Toxic gas production hazard.
Common Hazards of UN 2189
- TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Flammable; may be ignited by heat, sparks or flames.
- May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
Chemical Identity & Physical Properties
| Also known as | DichlorosilaneSilicon dichlorideDCSSilylene dichlorideChlorosilane (SiH2Cl2) |
| CAS Number | 4109-96-0 |
| Appearance | Colorless gas with a pungent, acrid odor. Liquefied under pressure. Extremely reactive and pyrophoric (ignites spontaneously in air). |
| Flash Point | Not applicable (pyrophoric gas - ignites spontaneously in air) |
| Boiling Point | 8.3°C (47°F) |
| Vapor Density | 3.5 (heavier than air) |
| Water Reactivity | Reacts violently with water producing corrosive hydrochloric acid, hydrogen gas, and heat. Do not use water. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2189
Extinguishing Media
Dry chemical, CO2, or sand only. Do not use water or foam. Let small fires burn out.
PPE Requirements
⚠️ Level A required for spill response. Full encapsulating chemical protective suit with SCBA. Butyl rubber gloves minimum for incidental contact.
Isolation & Evacuation
ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/rail car involved in fire. Toxic gas production hazard.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 119).
First Actions for a UN 2189 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.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- 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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📋 Copy & Share Field Card
UN 2189 — DichlorosilaneHAZMAT RADIO NOTE — UN 2189
Product: Dichlorosilane
Class 2 / Toxic Gas / ERG 119
PPE: Level A required for spill response. Full encapsulating chemical protective suit with SCBA. Butyl rubber gloves minimum for incidental contact.
ISOLATION: ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/rail car involved in fire. Toxic gas production hazard.
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 2189 — Dichlorosilane
Class: 2 | Placard: Toxic Gas | ERG Guide: 119
Appearance: Colorless gas with a pungent, acrid odor. Liquefied under pressure. Extremely reactive and pyrophoric (ignites spontaneously in air).
Water Reactivity: Reacts violently with water producing corrosive hydrochloric acid, hydrogen gas, and heat. Do not use water.
Extinguishing: Dry chemical, CO2, or sand only. Do not use water or foam. Let small fires burn out.
PPE: Level A required for spill response. Full encapsulating chemical protective suit with SCBA. Butyl rubber gloves minimum for incidental contact.
Isolation: ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/rail car involved in fire. Toxic gas production hazard.
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
• Fire will produce irritating, corrosive and/or toxic gases.
— 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.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/2189 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2189 Dichlorosilane Cls2 ERG119 | ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/ | allfirefighter.com/hazmat/un/2189SMS / 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/2189
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Frequently Asked Questions about UN 2189
TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Flammable; may be ignited by heat, sparks or flames. May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Vapors from liquefied gas are initially heavier than air and spread along ground.
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 required for spill response. Full encapsulating chemical protective suit with SCBA. Butyl rubber gloves minimum for incidental contact.
Water reactivity: Reacts violently with water producing corrosive hydrochloric acid, hydrogen gas, and heat. Do not use water.. Recommended extinguishing: Dry chemical, CO2, or sand only. Do not use water or foam. Let small fires burn out..
ERG Guide 119 recommendation: ERG 119: Isolate spill/leak 100m all directions. Evacuate 800m downwind if tank/rail car involved in fire. Toxic gas production hazard.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 119 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.