UN 2381 — Dimethyl disulphide
Placard: Flammable. ERG Guide 131. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2381 is Dimethyl disulphide, a toxic flammable sulfur-containing liquid assigned to ERG Guide 131. Strong odor does not replace SCBA or air monitoring.
Hazard overview: TOXIC and FLAMMABLE sulfur-containing liquid; inhalation, ingestion or skin absorption may cause serious injury. Vapors may ignite and form explosive mixtures with air. Strong garlic/onion odor may be noticeable, but odor is not a reliable exposure-control method.
Response guidance: For UN 2381, isolate the area, eliminate ignition sources and use SCBA. Keep vapors out of drains, prevent toxic/corrosive runoff and select foam, dry chemical or CO2 using SDS and ERG 131.
Firefighter training notes: Training for UN 2381 should emphasize toxic/corrosive exposure, SCBA use, skin-contact prevention, sewer flashback, decontamination, runoff control and foam selection. Use ERG 131, SDS and local SOP.
Regulatory context: Dimethyl disulphide is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Dimethyl disulphide should be stored in approved flammable/toxic or corrosive-liquid containers with ventilation, secondary containment and separation from heat, ignition sources, oxidizers and incompatible materials.
UN 2381 Quick Details
Common Hazards of UN 2381
- TOXIC and FLAMMABLE sulfur-containing liquid; inhalation, ingestion or skin absorption may cause serious injury.
- Vapors may ignite and form explosive mixtures with air.
- Strong garlic/onion odor may be noticeable, but odor is not a reliable exposure-control method.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Fire may produce sulfur oxides, carbon monoxide and irritating/toxic smoke.
- Runoff may create fire, odor and toxic contamination hazards.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a strong, disagreeable garlic-like or onion-like odor. Volatile and immiscible with water.
| Also known as | DMDSMethyl disulfide2,3-DithiabutaneDimethyl disulfide |
| CAS Number | 624-92-0 |
| Appearance | Colorless to pale yellow liquid with a strong, disagreeable garlic-like or onion-like odor. Volatile and immiscible with water. |
| Flash Point | -15°C (5°F) |
| Boiling Point | 109-110°C (228-230°F) |
| Vapor Density | 3.24 (heavier than air) |
| Water Reactivity | No significant reaction; insoluble in water |
Fireground Response Guidance — UN 2381
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing; avoid skin contact.
Isolation & Evacuation
First Actions for a UN 2381 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream; keep responders out of low vapor areas.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, mist or smoke and avoid skin or eye contact.
- Prevent toxic, alkaline or corrosive runoff from entering drains and waterways.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 131, SDS, shipping papers and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2381 — Dimethyl disulphideUse 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.