UN 1228 — Mercaptan mixture, liquid, flammable, poisonous, n.o.s.
Placard: Flammable. ERG Guide 131. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1228 is Mercaptan mixture, liquid, flammable, poisonous, n.o.s., a toxic flammable mercaptan liquid assigned to ERG Guide 131. It has a strong sulfur odor, but odor should not replace monitoring, SCBA and exclusion control.
Hazard overview: UN 1228 combines flammable vapor, toxic exposure and severe odor-control hazards. Vapors may travel to ignition sources, while fire can generate irritating sulfur-containing gases.
Response guidance: For a UN 1228 incident, responders should confirm the product using shipping papers, container markings, SDS and ERG Guide 131. Establish incident command, isolate the area, stay upwind and uphill, remove ignition sources when safe, keep vapors or runoff out of sewers and use compatible fire-control agents from a protected position.
Firefighter training notes: Training for UN 1228 should emphasize combined toxicity, skin absorption, vapor travel, ignition control, air monitoring and decontamination. Common errors include treating the incident only as a fire, relying on odor and entering vapor areas without SCBA. Use ERG 131, SDS and incident command.
Regulatory context: Mercaptan mixture, liquid, flammable, poisonous, n.o.s. is regulated as a hazardous material and may have additional occupational exposure, environmental and waste controls because of toxicity as well as flammability. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Mercaptan mixture, liquid, flammable, poisonous, n.o.s. should be stored in tightly closed compatible containers in a cool, dry, well-ventilated flammable-liquid area with exposure controls, secondary containment and drain protection. Keep away from heat, ignition sources, oxidizers and incompatible materials.
UN 1228 Quick Details
Common Hazards of UN 1228
- TOXIC and FLAMMABLE; mercaptan vapors may cause serious exposure while also forming ignitable mixtures.
- Vapors may form explosive mixtures with air and travel to an ignition source.
- Vapors are heavier than air and may collect in low, confined or sewer areas.
- Liquid or vapor may irritate or injure eyes, skin and respiratory tissue.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or spill control may cause environmental contamination.
- Containers may rupture or explode when heated.
- Strong odor may be noticeable at low levels but should not replace air monitoring or respiratory protection.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with extremely strong, offensive, garlic-like or skunk-like odor. Mercaptans are sulfur-containing organic compounds detectable at very low concentrations.
| Also known as | Thiol mixtureSulfhydryl compound mixtureAlkyl mercaptan blendFlammable mercaptan solution |
| Appearance | Clear to pale yellow liquid with extremely strong, offensive, garlic-like or skunk-like odor. Mercaptans are sulfur-containing organic compounds detectable at very low concentrations. |
| Flash Point | Typically below 23°C (73°F), varies by specific mercaptan composition |
| Boiling Point | Variable, typically 35-150°C (95-302°F) depending on mercaptan components |
| Vapor Density | Heavier than air (typically 2-4), vapors accumulate in low areas |
| Water Reactivity | No significant reaction with water, but immiscible and will float on water surface |
Fireground Response Guidance — UN 1228
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Chemical-resistant gloves, boots, splash protection and protective clothing should be selected using SDS, monitoring results and incident command because inhalation or skin absorption may be serious.
Isolation & Evacuation
First Actions for a UN 1228 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.
- Avoid breathing vapors and avoid skin or eye contact with liquid.
- 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, fire involvement or strong vapor movement, expand isolation and consider downwind evacuation based on monitoring and incident command.
- Use ERG Guide 131, shipping papers, SDS and local SOP for protective actions and entry decisions.
📋 Copy & Share Field Card
UN 1228 — Mercaptan mixture, liquid, flammable, poUse 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.