☣️ UN 1781 • CLASS 8
UN 1781 — Hexadecyltrichlorosilane
Placard: Corrosive. ERG Guide 156. 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.
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UN 1781 Quick Details
UN 1781
Product name: Hexadecyltrichlorosilane
DOT Class: 8
Placard type: Corrosive
ERG Guide: 156 (check current ERG)
Initial isolation: ERG 156: Isolate spill/leak area immediately for at least 50m in all directions. If tank/rail car involved in fire, isolate 800m all directions and consider initial evacuation for 800m.
Common Hazards of UN 1781
- Combustible material: may burn but does not ignite readily.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
- 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.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
- TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
Chemical Identity & Physical Properties
| Also known as | Hexadecyltrichlorosilanen-HexadecyltrichlorosilaneCetyl trichlorosilaneTrichlorohexadecylsilane |
| CAS Number | 5894-60-0 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid, hydrochloric acid-like odor. Corrosive organosilicon compound that fumes in moist air. |
| Flash Point | 93C (200F) — combustible liquid |
| Boiling Point | Approximately 333C (631F) at 760 mmHg |
| Vapor Density | Approximately 10 (heavier than air, relative to air=1) |
| Water Reactivity | Reacts violently with water, releasing heat and toxic/corrosive hydrogen chloride gas (HCl). 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 1781
Extinguishing Media
Dry chemical, CO2, dry sand only. Do not use water or foam directly on material. Water may be used from a distance to cool surrounding containers.
PPE Requirements
⚠️ Level B minimum (splash protection); full chemical-resistant suit, gloves, boots. SCBA required. Avoid contact with moisture and skin. Immediate decontamination critical.
Isolation & Evacuation
ERG 156: Isolate spill/leak area immediately for at least 50m in all directions. If tank/rail car involved in fire, isolate 800m all directions and consider initial evacuation for 800m.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 156).
First Actions for a UN 1781 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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📋 Copy & Share Field Card
UN 1781 — HexadecyltrichlorosilaneHAZMAT RADIO NOTE — UN 1781
Product: Hexadecyltrichlorosilane
Class 8 / Corrosive / ERG 156
PPE: Level B minimum (splash protection); full chemical-resistant suit, gloves, boots. SCBA required. Avoid contact with moisture and skin. Immediate decontamination critical.
ISOLATION: ERG 156: Isolate spill/leak area immediately for at least 50m in all directions. If tank/rail car involved in fire, isolate 800m all directions and consider initial evacuation for 800m.
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 1781 — Hexadecyltrichlorosilane
Class: 8 | Placard: Corrosive | ERG Guide: 156
Appearance: Colorless to pale yellow liquid with a pungent, acrid, hydrochloric acid-like odor. Corrosive organosilicon compound that fumes in moist air.
Water Reactivity: Reacts violently with water, releasing heat and toxic/corrosive hydrogen chloride gas (HCl). Do not use water directly on material.
Extinguishing: Dry chemical, CO2, dry sand only. Do not use water or foam directly on material. Water may be used from a distance to cool surrounding containers.
PPE: Level B minimum (splash protection); full chemical-resistant suit, gloves, boots. SCBA required. Avoid contact with moisture and skin. Immediate decontamination critical.
Isolation: ERG 156: Isolate spill/leak area immediately for at least 50m in all directions. If tank/rail car involved in fire, isolate 800m all directions and consider initial evacuation for 800m.
— Key Hazards —
• Combustible material: may burn but does not ignite readily.
• Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
• When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
— 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/1781 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1781 Hexadecyltrichlorosilane Cls8 ERG156 | allfirefighter.com/hazmat/un/1781SMS / 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/1781
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Frequently Asked Questions about UN 1781
Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion 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. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
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 (splash protection); full chemical-resistant suit, gloves, boots. SCBA required. Avoid contact with moisture and skin. Immediate decontamination critical.
Water reactivity: Reacts violently with water, releasing heat and toxic/corrosive hydrogen chloride gas (HCl). Do not use water directly on material.. Recommended extinguishing: Dry chemical, CO2, dry sand only. Do not use water or foam directly on material. Water may be used from a distance to cool surrounding containers..
ERG Guide 156 recommendation: ERG 156: Isolate spill/leak area immediately for at least 50m in all directions. If tank/rail car involved in fire, isolate 800m all directions and consider initial evacuation for 800m.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 156 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.