☣️ UN 1064 • CLASS 2
UN 1064 — Methyl mercaptan
Placard: Toxic Gas. ERG Guide 117. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
Methyl mercaptan is a highly toxic and extremely hazardous substance that can be fatal if inhaled or absorbed through the skin. It is shipped as a liquefied compressed gas.
Hazard overview: Methyl mercaptan is highly toxic and can cause serious health effects, including respiratory problems and damage to the central nervous system. The gas is also highly volatile and flammable.
Response guidance: In the event of a spill or leak, isolate the area immediately and evacuate downwind. Responders should wear Level A protective gear, including a self-contained breathing apparatus and a chemical-resistant suit.
Advertisement
UN 1064 Quick Details
UN 1064
Product name: Methyl mercaptan
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 117 (check current ERG)
Initial isolation: ERG 117: isolate spill/leak area immediately 100m in all directions; evacuate initial 800m downwind for large spills; 1600m evacuation for fire scenarios
Common Hazards of UN 1064
- TOXIC; Extremely Hazardous.
- May be fatal if inhaled or absorbed through skin.
- Initial odor may be irritating or foul and may deaden your sense of smell.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- These materials are extremely flammable.
- May form explosive mixtures with air.
Chemical Identity & Physical Properties
Methyl mercaptan is a colorless gas with a strong, unpleasant odor resembling rotten cabbage or garlic at low concentrations.
| Also known as | MethanethiolMethyl sulfhydrateThiomethyl alcoholMercaptomethaneMethyl thioalcohol |
| CAS Number | 74-93-1 |
| Appearance | Colorless gas with a strong, unpleasant odor resembling rotten cabbage or garlic at low concentrations. Highly volatile and flammable. Shipped as a liquefied compressed gas. |
| Flash Point | -47C (-53F) |
| Boiling Point | 6C (43F) |
| Vapor Density | 1.66 (heavier than air) |
| Water Reactivity | Soluble in water with no significant reaction; may hydrolyze slowly in aqueous solutions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1064
Extinguishing Media
Water spray, fog, or regular foam; CO2 and dry chemical suitable for small fires
PPE Requirements
⚠️ Level A for unknown concentrations or IDLH conditions; Level B minimum with SCBA and chemical-resistant suit; extreme skin absorption hazard
Level A protective gear is required for unknown concentrations or IDLH conditions, including a self-contained breathing apparatus and a chemical-resistant suit, due to the extreme skin absorption hazard.
Isolation & Evacuation
ERG 117: isolate spill/leak area immediately 100m in all directions; evacuate initial 800m downwind for large spills; 1600m evacuation for fire scenarios
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 117).
First Actions for a UN 1064 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- See Table 1 - Initial Isolation and Protective Action Distances.
Advertisement
📋 Copy & Share Field Card
UN 1064 — Methyl mercaptanHAZMAT RADIO NOTE — UN 1064
Product: Methyl mercaptan
Class 2 / Toxic Gas / ERG 117
PPE: Level A for unknown concentrations or IDLH conditions; Level B minimum with SCBA and chemical-resistant suit; extreme skin absorption hazard
ISOLATION: ERG 117: isolate spill/leak area immediately 100m in all directions; evacuate initial 800m downwind for large spills; 1600m evacuation for fire scenarios
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 1064 — Methyl mercaptan
Class: 2 | Placard: Toxic Gas | ERG Guide: 117
Appearance: Colorless gas with a strong, unpleasant odor resembling rotten cabbage or garlic at low concentrations. Highly volatile and flammable. Shipped as a liquefied compressed gas.
Water Reactivity: Soluble in water with no significant reaction; may hydrolyze slowly in aqueous solutions
Extinguishing: Water spray, fog, or regular foam; CO2 and dry chemical suitable for small fires
PPE: Level A for unknown concentrations or IDLH conditions; Level B minimum with SCBA and chemical-resistant suit; extreme skin absorption hazard
Isolation: ERG 117: isolate spill/leak area immediately 100m in all directions; evacuate initial 800m downwind for large spills; 1600m evacuation for fire scenarios
— Key Hazards —
• TOXIC; Extremely Hazardous.
• May be fatal if inhaled or absorbed through skin.
• Initial odor may be irritating or foul and may deaden your sense of smell.
— First Actions —
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
• Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
SOURCE: allfirefighter.com/hazmat/un/1064 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1064 Methyl mercaptan Cls2 ERG117 | ERG 117: isolate spill/leak area immediately 100m in all directions; evacuate in | allfirefighter.com/hazmat/un/1064SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/methyl-mercaptan-un-1064
Advertisement
Frequently Asked Questions about UN 1064
Yes, UN 1064 is a highly volatile and flammable gas.
Methyl mercaptan can cause serious health effects, including respiratory problems and damage to the central nervous system.
Isolate the area immediately, evacuate downwind, and wear Level A protective gear, including a self-contained breathing apparatus and a chemical-resistant suit.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.