UN 3336 — Mercaptan mixture, liquid, flammable, n.o.s.
Placard: Flammable. ERG Guide 130. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3336 is Mercaptan mixture, liquid, flammable, n.o.s., a flammable mercaptan mixture assigned to ERG Guide 130. Flashback, low-area vapor and odor unreliability are key hazards.
Hazard overview: HIGHLY FLAMMABLE mercaptan mixture; vapors may ignite and form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. Strong odor is not a reliable safety indicator; irritation or toxicity may occur above safe limits.
Response guidance: For UN 3336, isolate the area, avoid exposure and use SCBA where vapor, dust, smoke or fire is present. Verify exact controls with SDS and ERG 130.
Firefighter training notes: Training for UN 3336 should emphasize product verification, SCBA use, exposure control, decontamination, runoff containment and SDS/shipping paper review. Use ERG 130, SDS and local SOP.
Regulatory context: Mercaptan mixture, liquid, flammable, n.o.s. is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Mercaptan mixture, liquid, flammable, n.o.s. should be stored in tightly closed compatible containers or packages with ventilation, secondary containment, restricted access and SDS-based segregation from incompatible materials.
UN 3336 Quick Details
Common Hazards of UN 3336
- HIGHLY FLAMMABLE mercaptan mixture; vapors may ignite and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Strong odor is not a reliable safety indicator; irritation or toxicity may occur above safe limits.
- Vapor explosion hazard exists in drains, sewers, basements and confined areas.
- Fire may produce sulfur oxides and irritating/toxic smoke.
- Liquid may float on water and spread fire or contamination.
- Exact mercaptan blend controls toxicity, flash point and vapor behavior.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with strong, offensive, garlic-like or skunk-like odor. Highly volatile at room temperature.
| Also known as | Thiol mixtureMercaptan blendAlkyl mercaptan mixtureSulfhydryl compound mixture |
| Appearance | Clear to pale yellow liquid with strong, offensive, garlic-like or skunk-like odor. Highly volatile at room temperature. |
| Flash Point | Below 23C (73F) - varies by specific mercaptan composition |
| Boiling Point | Typically 35-200C (95-392F) depending on mixture composition |
| Vapor Density | 2-4 (heavier than air) - mercaptan vapors will settle in low areas |
| Water Reactivity | No significant reaction with water, but insoluble and will float; vapors still flammable above water surface |
Fireground Response Guidance — UN 3336
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA where vapor, dust, smoke or fire is present. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 3336 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.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, dust, gas, mist, smoke or aerosols and avoid skin or eye contact.
- Do not touch damaged containers, cylinders, packages or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff, residue and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 130, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3336 — Mercaptan mixture, liquid, flammable, n.Use 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.