UN 1162 — Dimethyldichlorosilane
Placard: Flammable. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Dimethyldichlorosilane is a colorless to pale yellow fuming liquid with a pungent, irritating, hydrochloric acid-like odor, commonly used in various industrial applications. It is essential to handle this substance with care due to its highly flammable and reactive properties.
Hazard overview: Dimethyldichlorosilane is highly flammable and can be easily ignited by heat, sparks, or flames, posing a significant fire hazard. Its vapors can also form explosive mixtures with air, increasing the risk of explosion, and it reacts violently with water, producing hydrochloric acid and heat.
Response guidance: In case of a dimethyldichlorosilane spill, it is crucial to isolate the area, evacuate people, and respond with dry chemical, CO2, or dry sand to prevent the fire from spreading. Emergency responders should wear Level B minimum protective gear, including SCBA and a full chemical-resistant suit, and avoid using water or foam.
UN 1162 Quick Details
Common Hazards of UN 1162
- 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
Dimethyldichlorosilane is a colorless to pale yellow fuming liquid with a pungent, irritating, hydrochloric acid-like odor, and it reacts violently with water, producing dense white fumes of hydrochloric acid.
| Also known as | DichlorodimethylsilaneDimethyldichlorosilaneDMDCSSilane, dichlorodimethyl- |
| CAS Number | 75-78-5 |
| Appearance | Colorless to pale yellow fuming liquid with a pungent, irritating, hydrochloric acid-like odor. Reacts violently with water, producing dense white fumes of hydrochloric acid. |
| Flash Point | -16C (3F) |
| Boiling Point | 70C (158F) |
| Vapor Density | 4.4 (heavier than air) |
| Water Reactivity | Reacts violently with water, producing hydrochloric acid and heat. DO NOT USE WATER directly on material. |
Fireground Response Guidance — UN 1162
Extinguishing Media
PPE Requirements
When handling dimethyldichlorosilane, it is essential to wear Level B minimum protective gear, including SCBA, a full chemical-resistant suit, and butyl rubber or Viton gloves, to prevent skin and eye contact.
Isolation & Evacuation
First Actions for a UN 1162 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
📋 Copy & Share Field Card
UN 1162 — DimethyldichlorosilaneUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.