UN 2966 — Thioglycol
Placard: Toxic. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2966 is Thioglycol, a toxic combustible mercaptan alcohol assigned to ERG Guide 153. Vapor, odor and sulfur-containing fire products are key concerns.
Hazard overview: TOXIC combustible mercaptan alcohol liquid; inhalation, ingestion or skin contact may cause injury. Combustible liquid; heated vapors may form ignitable mixtures with air. Strong odor does not reliably indicate safe exposure levels.
Response guidance: For UN 2966, isolate the area, avoid skin contact and use SCBA where dust, vapor, mist or fire is present. Contain runoff and verify controls with SDS and ERG 153.
Firefighter training notes: Training for UN 2966 should emphasize exposure routes, SCBA use, vapor/dust monitoring, decontamination, runoff containment and SDS verification. Use ERG 153, SDS and local SOP.
Regulatory context: Thioglycol is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Thioglycol should be stored in tightly closed compatible containers with ventilation, secondary containment, restricted access and SDS-based segregation from incompatible materials.
UN 2966 Quick Details
Common Hazards of UN 2966
- TOXIC combustible mercaptan alcohol liquid; inhalation, ingestion or skin contact may cause injury.
- Combustible liquid; heated vapors may form ignitable mixtures with air.
- Strong odor does not reliably indicate safe exposure levels.
- Liquid and vapor may irritate eyes, skin and respiratory tract.
- Fire may produce sulfur oxides, carbon monoxide and irritating/toxic smoke.
- Runoff may carry toxic sulfur-containing contamination.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with a strong, unpleasant mercaptan odor. Viscous consistency at room temperature.
| Also known as | 2-Mercaptoethanolbeta-MercaptoethanolThioethylene glycol2-HydroxyethanethiolMercaptoethanol |
| CAS Number | 60-24-2 |
| Appearance | Clear to pale yellow liquid with a strong, unpleasant mercaptan odor. Viscous consistency at room temperature. |
| Flash Point | 73°C (163°F) |
| Boiling Point | 157°C (315°F) |
| Vapor Density | 2.7 (heavier than air) |
| Water Reactivity | Soluble in water; no violent reaction but vapors may be released |
Fireground Response Guidance — UN 2966
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, dust, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2966 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.
- Avoid breathing vapor, dust, gas, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 153, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2966 — ThioglycolUse 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.