☣️ UN 1295 • CLASS 4
UN 1295 — Trichlorosilane
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.
Trichlorosilane is a highly reactive and corrosive substance that requires immediate attention in emergency situations. It is essential to follow proper procedures to prevent exposure and minimize damage.
Hazard overview: Trichlorosilane produces flammable and toxic gases on contact with water, and may ignite on contact with water or moist air. It also reacts violently with water, producing flammable hydrogen gas and corrosive hydrochloric acid fumes.
Response guidance: In case of fire, use dry chemical, sand, or carbon dioxide to extinguish the flames. Do not use water or foam directly on the material, and use water spray from a distance to cool containers.
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UN 1295 Quick Details
UN 1295
Product name: Trichlorosilane
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 139 (check current ERG)
Initial isolation: ERG 139: Initially isolate 150m in all directions. For large spills, isolate 800m downwind during day or 1500m at night. Evacuate immediate area if material is on fire or exposed to fire.
Common Hazards of UN 1295
- 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
Trichlorosilane is a colorless to slightly yellow fuming liquid with a pungent, acrid, irritating odor, and fumes in moist air forming white clouds of hydrochloric acid.
| Also known as | SilicochloroformTrichloromonosilaneTCSSilicon trichloride hydride |
| CAS Number | 10025-78-2 |
| Appearance | Colorless to slightly yellow fuming liquid with a pungent, acrid, irritating odor. Fumes in moist air forming white clouds of hydrochloric acid. |
| Flash Point | -28C (-18F) |
| Boiling Point | 32C (90F) |
| Vapor Density | 4.7 (heavier than air) |
| Water Reactivity | Reacts violently with water producing flammable hydrogen gas and corrosive hydrochloric acid fumes. 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 1295
Extinguishing Media
Dry chemical, sand, carbon dioxide. DO NOT use water or foam directly on material. Use water spray from distance to cool containers.
PPE Requirements
⚠️ Level A or B with full-face SCBA required. Chemical-resistant suit, gloves, and boots. Vapor-tight chemical protective suit for major spills.
Level A or B with full-face SCBA is required, along with a chemical-resistant suit, gloves, and boots, and a vapor-tight chemical protective suit for major spills.
Isolation & Evacuation
ERG 139: Initially isolate 150m in all directions. For large spills, isolate 800m downwind during day or 1500m at night. Evacuate immediate area if material is on fire or exposed to fire.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 139).
First Actions for a UN 1295 Incident
- 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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📋 Copy & Share Field Card
UN 1295 — TrichlorosilaneHAZMAT RADIO NOTE — UN 1295
Product: Trichlorosilane
Class 4 / Dangerous When Wet / ERG 139
PPE: Level A or B with full-face SCBA required. Chemical-resistant suit, gloves, and boots. Vapor-tight chemical protective suit for major spills.
ISOLATION: ERG 139: Initially isolate 150m in all directions. For large spills, isolate 800m downwind during day or 1500m at night. Evacuate immediate area if material is on fire or exposed to 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 1295 — Trichlorosilane
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 139
Appearance: Colorless to slightly yellow fuming liquid with a pungent, acrid, irritating odor. Fumes in moist air forming white clouds of hydrochloric acid.
Water Reactivity: Reacts violently with water producing flammable hydrogen gas and corrosive hydrochloric acid fumes. Do not use water directly on material.
Extinguishing: Dry chemical, sand, carbon dioxide. DO NOT use water or foam directly on material. Use water spray from distance to cool containers.
PPE: Level A or B with full-face SCBA required. Chemical-resistant suit, gloves, and boots. Vapor-tight chemical protective suit for major spills.
Isolation: ERG 139: Initially isolate 150m in all directions. For large spills, isolate 800m downwind during day or 1500m at night. Evacuate immediate area if material is on fire or exposed to fire.
— 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 —
• 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
SOURCE: allfirefighter.com/hazmat/un/1295 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1295 Trichlorosilane Cls4 ERG139 | ERG 139: Initially isolate 150m in all directions. For large spills, isolate 800 | allfirefighter.com/hazmat/un/1295SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/trichlorosilane-un-1295
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Frequently Asked Questions about UN 1295
Yes, Trichlorosilane is a flammable substance that can ignite on contact with water or moist air.
Use dry chemical, sand, or carbon dioxide to extinguish the flames, and do not use water or foam directly on the material.
No, do not use water or foam directly on Trichlorosilane, as it reacts violently with water and produces flammable hydrogen gas and corrosive hydrochloric acid fumes.
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.