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 At a Glance
UN 3336 (Mercaptan mixture, liquid, flammable) 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 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.