UN 2347 — Butyl mercaptan
Placard: Flammable. ERG Guide 130. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2347 At a Glance
UN 2347 (Butyl mercaptan) is listed as DOT Class 3 Flammable and is assigned to ERG Guide 130. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.