UN 1111 — Amyl mercaptan
Placard: Flammable. ERG Guide 130. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1111 is Amyl mercaptan, a Class 3 flammable mercaptan liquid assigned to ERG Guide 130. It has a strong sulfur-like odor and can create vapor flashback, fire and irritating exposure hazards.
Hazard overview: UN 1111 presents flammable vapor and odor-control hazards. Mercaptan vapors may travel to ignition sources, flash back and produce irritating or toxic sulfur-containing gases in fire.
Response guidance: For a UN 1111 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 out of sewers and use compatible Class B fire-control agents from a protected position.
Firefighter training notes: Training for UN 1111 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, ignoring low-area vapor collection and using non-compatible foam. Use ERG 130, SDS and local SOP.
Regulatory context: Amyl mercaptan 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 product, 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: Amyl mercaptan 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 1111 Quick Details
Common Hazards of UN 1111
- HIGHLY FLAMMABLE liquid; vapors may ignite easily and form explosive mixtures with air.
- Strong mercaptan odor may be detected at very low levels but should not be used as the only exposure warning.
- Vapors are heavier than air and may travel to ignition sources or collect in low areas.
- Liquid or vapor may irritate eyes, skin and respiratory tissue.
- 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, offensive, skunk-like odor. Liquid at room temperature with characteristic mercaptan smell.
| Also known as | 1-PentanethiolPentyl mercaptann-Amyl mercaptanPentan-1-thiol |
| CAS Number | 110-66-7 |
| Appearance | Colorless to pale yellow liquid with a strong, offensive, skunk-like odor. Liquid at room temperature with characteristic mercaptan smell. |
| Flash Point | -18°C (0°F) |
| Boiling Point | 126°C (259°F) |
| Vapor Density | 3.6 (heavier than air) |
| Water Reactivity | No significant reaction; immiscible with water, floats on surface |
Fireground Response Guidance — UN 1111
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for fire, heavy vapor or confined-space exposure. Chemical-resistant gloves and splash protection are recommended for liquid contact; odor should not be used as the only exposure-control method.
Isolation & Evacuation
First Actions for a UN 1111 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 or fire involvement, expand isolation and consider downwind evacuation based on vapor movement, 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 1111 — Amyl 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.