UN 2347 — Butyl mercaptan
Placard: Flammable. ERG Guide 130. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2347 is Butyl mercaptan, a toxic flammable mercaptan assigned to ERG Guide 130. Its strong odor is not a substitute for air monitoring or respiratory protection.
Hazard overview: TOXIC and FLAMMABLE mercaptan liquid; inhalation, ingestion or skin absorption may cause serious injury. Vapors may ignite and form explosive mixtures with air. Very strong odor may be detectable at low levels, but odor is not a safe exposure guide.
Response guidance: For UN 2347, isolate the area, eliminate ignition sources, keep vapors out of drains and use SCBA in vapor or fire conditions. Cool containers from a protected distance and select foam/dry chemical/CO2 based on the SDS.
Firefighter training notes: Training for UN 2347 should emphasize toxic vapor recognition, SCBA use, skin-contact prevention, sewer flashback, container cooling, decontamination and runoff control. Use ERG 130, SDS and local SOP.
Regulatory context: Butyl mercaptan 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: Butyl mercaptan should be stored in approved flammable-liquid containers with ventilation, bonding/grounding where required, spill containment and separation from heat, ignition sources, oxidizers and incompatible materials.
UN 2347 Quick Details
Common Hazards of UN 2347
- TOXIC and FLAMMABLE mercaptan liquid; inhalation, ingestion or skin absorption may cause serious injury.
- Vapors may ignite and form explosive mixtures with air.
- Very strong odor may be detectable at low levels, but odor is not a safe exposure guide.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Fire may produce sulfur oxides and other irritating/toxic gases.
- Runoff to sewers may create fire, explosion and odor/toxic contamination hazards.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a strong, offensive, skunk-like odor. Liquid at room temperature with extremely low odor threshold.
| Also known as | 1-Butanethioln-Butyl mercaptanButane-1-thiolButyl hydrosulfideThiobutyl alcohol |
| CAS Number | 109-79-5 |
| Appearance | Colorless to pale yellow liquid with a strong, offensive, skunk-like odor. Liquid at room temperature with extremely low odor threshold. |
| Flash Point | -2C (28F) |
| Boiling Point | 98C (208F) |
| Vapor Density | 3.1 (heavier than air) |
| Water Reactivity | No significant reaction with water; insoluble and floats on water surface |
Fireground Response Guidance — UN 2347
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 2347 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.
- 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 130, SDS, shipping papers and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2347 — Butyl mercaptanUse 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.