UN 1162 — Dimethyldichlorosilane
Placard: Flammable. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1162 is Dimethyldichlorosilane, a flammable water-reactive corrosive liquid assigned to ERG Guide 155. It can ignite, fume in moist air and release corrosive hydrogen chloride when exposed to water.
Hazard overview: UN 1162 presents flammable vapor, corrosive fume and violent water-reactivity hazards. Water or moisture can generate heat and dense acid fumes, while vapors may travel to ignition sources and flash back.
Response guidance: For a UN 1162 incident, responders should confirm the product using shipping papers, container markings, SDS and ERG Guide 155. Establish incident command, isolate the area, stay upwind and uphill, remove ignition sources when safe, keep vapors or runoff out of sewers and use compatible Class B fire-control agents from a protected position.
Firefighter training notes: Training for UN 1162 should emphasize flammable vapor behavior, water-reactive corrosive fuming, HCl release, dry-agent selection and runoff control. Common errors include applying water or foam directly, entering without SCBA and ignoring low-area vapor travel. Use ERG 155, SDS and hazmat SOP.
Regulatory context: Dimethyldichlorosilane is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Dimethyldichlorosilane should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, heat, ignition sources, oxidizers and incompatible materials. Protect containers from corrosion, impact and unauthorized access, with dry spill-control materials available where required.
UN 1162 Quick Details
Common Hazards of UN 1162
- HIGHLY FLAMMABLE and WATER-REACTIVE; vapors may form explosive mixtures with air.
- Reacts with water or moisture to release heat and corrosive hydrogen chloride fumes.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Liquid and fumes are corrosive to eyes, skin and respiratory tissue.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff or water contact may spread corrosive contamination.
- Containers may rupture or explode when heated or contaminated with water.
Chemical Identity & Physical Properties
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.
| 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
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Chemical-resistant protective clothing, gloves, boots and eye/face protection should be selected from SDS and incident command because fumes and liquid are corrosive and water-reactive.
Isolation & Evacuation
First Actions for a UN 1162 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Eliminate ignition sources if it is safe to do so.
- Do not touch or walk through spilled liquid unless properly trained and wearing appropriate protective equipment.
- Avoid breathing vapors and avoid skin or eye contact with liquid.
- Keep water away from the released material unless incident command confirms a compatible use for cooling or vapor control.
- Ventilate closed spaces before entering, but only if properly trained, equipped and authorized by incident command.
- Isolate the spill or leak area for at least 50 meters (150 feet) in all directions.
- For large spills, fire involvement or strong vapor movement, expand isolation and consider downwind evacuation based on monitoring and incident command.
- Use ERG Guide 155, shipping papers, SDS and local SOP for protective actions and entry decisions.
📋 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.