UN 3054 — Cyclohexyl mercaptan
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3054 At a Glance
UN 3054 (Cyclohexyl mercaptan) is listed as DOT Class 3 Flammable and is assigned to ERG Guide 129. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
Cyclohexyl mercaptan (UN 3054) is a flammable, toxic mercaptan liquid with a strong sulfur odor. Response priorities are ignition control, vapor control and exposure prevention.
Hazard overview: UN 3054 vapors can collect in low areas, flash back and produce toxic sulfur-containing smoke in fire. Odor can be detected at low levels but does not prove the area is safe.
Response guidance: Isolate the area, control ignition sources and keep responders upwind. Use alcohol-resistant foam, dry chemical or CO2 for fire control and water spray only for cooling containers. Prevent runoff and avoid liquid contact.
Firefighter training notes: Train crews to control ignition sources and manage odor complaints without relying on odor as an exposure limit.
Regulatory context: UN 3054 is a regulated flammable/toxic mercaptan entry; ERG 129 and SDS should guide initial response.
Storage & handling: Store away from oxidizers, ignition sources and heat in tightly closed containers with ventilation and spill containment.
UN 3054 Quick Details
Common Hazards of UN 3054
- Flammable liquid; vapors can ignite from heat, sparks or flames.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Toxic or irritating exposure can occur by inhalation, ingestion or skin contact.
- Strong mercaptan odor can cause complaints but is not a safe exposure indicator.
- Fire may release sulfur oxides and other toxic gases.
- Runoff may spread contamination and odor over a wide area.
- Containers may rupture when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a strong, unpleasant sulfur or skunk-like odor. Oily consistency at room temperature.
| Also known as | CyclohexanethiolCyclohexyl thiolMercaptocyclohexaneCyclohexyl hydrosulfide |
| CAS Number | 1569-69-3 |
| Appearance | Colorless to pale yellow liquid with a strong, unpleasant sulfur or skunk-like odor. Oily consistency at room temperature. |
| Flash Point | 43°C (109°F) |
| Boiling Point | 158-159°C (316-318°F) |
| Vapor Density | 4.0 (heavier than air) |
| Water Reactivity | No significant reaction with water; immiscible and floats on water surface |
Fireground Response Guidance — UN 3054
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant clothing. Select glove and suit materials from the SDS for mercaptan liquid contact.
Isolation & Evacuation
First Actions for a UN 3054 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Eliminate ignition sources; use non-sparking tools and control traffic around the spill.
- Keep unauthorized personnel away and stay upwind, uphill and upstream.
- Avoid breathing vapors and prevent liquid contact with skin, eyes and clothing.
- Do not enter low areas, drains or confined spaces unless trained and equipped.
- Use ERG 131, SDS, shipping papers and monitoring to set isolation and evacuation distances.
- Contain runoff only if it can be done safely with proper PPE.
📋 Copy & Share Field Card
UN 3054 — Cyclohexyl 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.