UN 1164 — Dimethyl sulphide
Placard: Flammable. ERG Guide 130. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1164 is Dimethyl sulphide, a Class 3 flammable sulfur-containing liquid assigned to ERG Guide 130. It is volatile, strongly odorous and capable of forming explosive vapor-air mixtures.
Hazard overview: UN 1164 presents flammable vapor, flashback and odor/exposure hazards. Strong odor may be noticed at low levels, but responders should rely on monitoring and SCBA rather than smell; fire may produce sulfur-containing toxic gases.
Response guidance: For a UN 1164 incident, responders should confirm the product using shipping papers, container markings, SDS and ERG Guide 130. 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 1164 should emphasize flammable liquid vapor travel, flashback, sewer vapor explosion risk, foam compatibility, container cooling and atmospheric monitoring. Common errors include standing downwind, allowing runoff into drains and ignoring low-area vapor collection. Use ERG 130, SDS and local SOP.
Regulatory context: Dimethyl sulphide 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: Dimethyl sulphide should be stored in tightly closed compatible containers in a cool, dry, well-ventilated flammable-liquid storage area. Keep away from heat, sparks, open flames, oxidizers and incompatible materials, with bonding/grounding, secondary containment and drain protection where required.
UN 1164 Quick Details
Common Hazards of UN 1164
- HIGHLY FLAMMABLE sulfur-containing liquid; vapors may ignite easily.
- Vapors may form explosive mixtures with air and flash back to the source.
- Strong odor may be detected at low levels but should not be used as the only exposure warning.
- Vapors are heavier than air and may collect in low or confined areas.
- Fire may produce irritating or toxic sulfur-containing gases.
- Runoff to sewer may create fire, explosion or odor-control hazards.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a strong, disagreeable odor resembling decayed cabbage or garlic. Highly volatile at room temperature.
| Also known as | DMSMethyl sulfide2-ThiapropaneDimethyl thioetherMethyl monosulfide |
| CAS Number | 75-18-3 |
| Appearance | Colorless to pale yellow liquid with a strong, disagreeable odor resembling decayed cabbage or garlic. Highly volatile at room temperature. |
| Flash Point | -37°C (-35°F) |
| Boiling Point | 37°C (99°F) |
| Vapor Density | 2.1 (heavier than air) |
| Water Reactivity | No significant reaction with water; slightly soluble |
Fireground Response Guidance — UN 1164
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for fire, heavy vapor or confined-space exposure. Chemical-resistant gloves, splash protection and protective clothing should be selected using SDS, product concentration and incident command.
Isolation & Evacuation
First Actions for a UN 1164 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.
- 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 130, shipping papers, SDS and local SOP for protective actions and entry decisions.
📋 Copy & Share Field Card
UN 1164 — Dimethyl sulphideUse 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.